Power transmitting device

Abstract

 A power transmitting device (100) for converting a reciprocating motion of a piston (15) into a rotational motion. The piston (15) is reciprocated in a cylinder (11) of a reciprocating engine to perform suction, compression, explosion and exhaust. The power transmitting device (100) includes a connecting member (21) supported to the piston (15); a guide member (25,26) for linearly guiding the connecting member (21); a power transmitting member supported to the connecting member (21); a cam member (31,31') having a cylindrical surface on which a cam having a predetermined cam curve is formed, the cam being engaged with the power transmitting member; and a drive shaft (30) integral with the cam member (31). The drive shaft (30) is rotated by a linear reciprocating motion of the power transmitting member in a plane perpendicular to a direction of the linear reciprocating motion of the power transmitting member. With this arrangement, the drive shaft (30) extends in a direction parallel to a reciprocating direction of the piston, thereby making the construction of the power transmitting device greatly compact in a radial direction thereof. Further, the power transmitting device (100) is equivalent to a power transmitting device including a primary reduction gear having a reduction ratio to be decided by the cam curve of the cam, thereby smoothly obtaining a high torque.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

[0001] The present invention relates to a power transmitting device for converting a linear reciprocating motion of a piston in a reciprocating engine into a rotational motion in a plane perpendicular to a direction of the linear reciprocating motion of the piston.

2. Description of the Prior Art

[0002] Conventionally, a positive-displacement internal combustion engine is classified into a reciprocating engine and a rotary engine from the viewpoint of a piston motion.

[0003] The reciprocating engine is of a type such that a reciprocating motion of the piston is converted through a connecting rod into a rotational motion of a crank shaft to obtain a power, and it is most used and known in the art.

[0004] In the conventional reciprocating engine, a direction of the reciprocating motion of the piston is perpendicular to an axial direction of the crank shaft.

[0005] Accordingly, the piston and a cylinder receiving the piston are relatively compact, but a motion converting mechanism including the connecting rod is largely expanded in the direction perpendicular to the direction of the reciprocating motion of the piston. Further, as the rotation of the crank shaft is utilized, the axial direction of the crank shaft is limited, so that it is difficult to make compact the construction of the conventional reciprocating engine inclusive of the crank shaft.

[0006] Further, in a reciprocating engine having a plurality of cylinders, a reduction gear is additionally included to cause an increase in size of the engine.

[0007] Further, in a reciprocating engine requiring valve control in a suction stroke and an exhaust stroke, such as a four-cycle engine, another mechanism (e.g., overhead cam mechanism) for transmitting the rotation of the crank shaft to a head portion of the piston is provided.

[0008] That is, the valve control in the four-cycle engine is effected by such a mechanism to perform a series of suction, compression, explosion and exhaust strokes.

[0009] However, it is considerably difficult to make the four-cycle engine compact in providing such a mechanism, and a timing error is apt to occur in a high-speed rotational region of the engine.

SUMMARY OF THE INVENTION

[0010] It is accordingly an object of the present invention to provide a power transmitting device incorporating a reduction mechanism which can be made compact by arranging a power output shaft of a reciprocating engine having a plurality of cylinders in parallel to a direction of a reciprocating motion of pistons in the cylinders.

[0011] It is another object of the present invention to provide a power transmitting device which can be made compact by arranging a power output shaft of a four-cycle engine in parallel to a direction of a reciprocating motion of pistons, and can improve a responsive performance of suction and exhaust valves in suction and exhaust strokes up to a high-speed region of the engine.

[0012] According to the present invention, there is provided a power transmitting device for converting a reciprocating motion of a piston into a rotational motion, said piston being reciprocated in a cylinder of a reciprocating engine to perform suction, compression, explosion and exhaust; said power transmitting device comprising a connecting member supported to said piston; a guide member for linearly guiding said connecting member; a power transmitting member supported to said connecting member; a cam member having a cylindrical surface on which a cam having a predetermined cam curve is formed, said cam being engaged with said power transmitting member; and a drive shaft integral with said cam member, said drive shaft being rotated by a linear reciprocating motion of said power transmitting member in a plane perpendicular to a direction of said linear reciprocating motion of said power transmitting member.

[0013] In the power transmitting device of the present invention in one aspect thereof, said engine has a plurality of cylinders opposed to each other in an axial direction of said cam member and/or arranged concentrically with respect to an axis of said cam member so as to extend in a direction parallel to said axis of said cam member.

[0014] In the power transmitting device of the present invention in another aspect thereof, said engine has a plurality of pairs of cylinders, said cylinders of each pair being axially opposed to each other; said connecting member is supported at opposite ends thereof to pistons received in said cylinders of each pair; and said plurality of pairs of cylinders are arranged concentrically with respect to an axis of said cam member so as to extend in a direction parallel to said axis of said cam member.

[0015] In the power transmitting device of the present invention in still another aspect thereof, said engine comprises a four-cycle engine having a plurality of cylinders arranged concentrically with respect to an axis of said cam member so as to extend in a direction parallel to said axis of said cam member; said connecting member is supported atone end thereof to a piston received in each of said cylinders; and said power transmitting device further comprises a suction valve and an exhaust valve provided at a head portion of said each cylinder, and a valve operating member fixed to said drive shaft and having a plate-like form expanding in a direction perpendicular to an axis of said drive shaft, for controlling start and end of operation of said suction valve in a suction stroke in said each cylinder and said exhaust valve in an exhaust stroke in said each cylinder in association with rotation of said drive shaft, said valve operating member having at least two cams adapted to engage said suction valve in an axial direction thereof and said exhaust valve in an axial direction thereof, respectively.

[0016] The linear reciprocating motion of the connecting member supported to the piston is transmitted through the power transmitting member and the cam to the drive shaft. Accordingly, the drive shaft is rotated in a plane perpendicular to a direction of the linear reciprocating motion of the power transmitting member. In the conventional reciprocating engine, the axial direction of the crank shaft is perpendicular to the linear reciprocating direction of the piston. To the contrary, in the power transmitting device of the present invention, the axial direction of the drive shaft is parallel to the linear reciprocating direction of the piston.

[0017] With this arrangement of the drive shaft with respect to the reciprocating direction of the piston, the construction of the power transmitting device can be made greatly compact in the radial direction of the drive shaft.

[0018] A rotational speed of the drive shaft per reciprocation of the piston depends upon a form of the cam curve of the cam per rotation of the cam member. Accordingly, the power transmitting device is equivalent to a power transmitting device incorporating a primary reduction gear, and a smooth rotation with a high torque can be obtained.

[0019] In the engine having a plurality of cylinders, the cylinders can be arranged around the cam member with a high degree of freedom. Further, the opposite ends of the drive shaft can be easily utilized as output ends. Thus, various arrangements and applications may be effected.

[0020] In the arrangement that the cylinders of each pair are axially opposed to each other in parallel to the axial direction of the drive shaft and that the pistons in the cylinders of each pair are connected to the respective connecting members, explosion in the axially opposed cylinders can be simultaneously performed to thereby eliminate action and reaction in the axial direction of the drive shaft.

[0021] In the arrangement that a plurality of cylinders are arranged concentrically with respect to the axis of the drive shaft at circumferential equal intervals and that explosion is performed sequentially at every interval in the cylinders, the drive shaft can be rotated smoothly with a high torque.

[0022] In the arrangement that the cylinders of each pair are axially opposed to each other in parallel to the axial direction of the drive shaft and that the connecting member is supported at its opposite ends to the pistons in the axially opposed cylinders, explosion is performed alternately in the axially opposed cylinders to apply a force to the connecting member in the position of a top dead center or a bottom dead center of both the pistons. Thus, the connecting member always receives a driving force in both the directions of the linear reciprocating motion of the pistons, thereby generating a continuous torque in the drive shaft.

[0023] In the arrangement that a plurality of pairs of cylinders are arranged concentrically with respect to the axis of the drive shaft, the cylinders of each pair being axially opposed to each other, and that explosion is performed sequentially, the drive shaft can be rotated very smoothly with a high torque.

[0024] In the four-cycle engine having a plurality of cylinders each provided with a suction valve and an exhaust valve, the valve operating member having a plate-like form expanding in a direction perpendicular to the axis of the drive shaft is fixed to the drive shaft, and the cams of the valve operating member are operatively engaged with the suction valve and the exhaust valve, respectively. That is, in the suction stroke and the exhaust stroke, the start and end of operation of the suction valve and the exhaust valve can be directly controlled by the drive shaft through the valve operating member fixed thereto.

[0025] Thus, the suction and exhaust valves are directly driven without any undue transmitting mechanism, thereby reducing a timing error. Accordingly, a responsive performance of the suction and exhaust valves can be improved to effect greatly smooth rotation of the output shaft up to a high-speed rotational region of the engine.

[0026] Other objects and features of the invention will be more fully understood from the following detailed description and appended claims when taken with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] 

Fig. 1 is a sectional view of a power transmitting device according to a first preferred embodiment of the present invention;

Fig. 2 is a cross section taken along the line A-A in Fig. 1;

Fig. 3A is an illustration of a characteristic curve of a cam groove shown in Fig. 1;

Fig. 3B is an illustration of a cam diagram of the cam groove;

Figs. 4A, 4B and 4C are schematic illustrations of a rotational force F_R of a cylindrical cam member shown in Fig. 1 at different inclined angles of the cam groove;

Fig. 5 is a sectional view of a power transmitting device according to a second preferred embodiment of the present invention;

Fig. 6 is a schematic illustration of arrangement of cylinders of an engine shown in Fig. 5;

Fig. 7 is a sectional view of a power transmitting device according to a third preferred embodiment of the present invention;

Fig. 8 is a sectional view of a power transmitting device according to a fourth preferred embodiment of the present invention;

Fig. 9 is a schematic illustration of arrangement of cylinders of an engine shown in Fig. 8;

Fig. 10 is a sectional view of a power transmitting device according to a fifth preferred embodiment of the present invention;

Fig. 11 is a schematic illustration of arrangement of cylinders of an engine shown in Fig. 10;

Fig. 12 is a sectional view of a power transmitting device according to a sixth preferred embodiment of the present invention;

Fig. 13 is a sectional view of a power transmitting device according to a seventh preferred embodiment of the present invention;

Fig. 14 is a schematic illustration of arrangement of cylinders of an engine shown in Fig. 13;

Fig. 15 is a cross section taken along the line E-E in Fig. 13;

Fig. 16 is a sectional view of a power transmitting device according to an eighth preferred embodiment of the present invention; and

Fig. 17 is a sectional view of a power transmitting device according to a ninth preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] There will now be described some preferred embodiments of the present invention with reference to the drawings.

First Preferred Embodiment

[0029] Referring to Fig. 1, reference numeral 100 generally denotes a power transmitting device according to a first preferred embodiment of the present invention. The power transmitting device 100 is constructed symmetrically with respect to a central drive shaft 30 to be hereinafter described. The power transmitting device 100 has a two-cycle two-cylinder engine. For simplicity of explanation, the construction of the right half of the power transmitting device 100 as viewed in Fig. 1 will be described.

[0030] A cylinder 11 and a cylinder head 13 are joined together with a sealing gasket or the like interposed therebetween, and a piston 15 is reciprocatably received in the cylinder 11. The cylinder 11 is fixed through a plate 19 to a housing 20. Although not shown, an ignition plug is threadedly engaged with the cylinder head 13, and an electrical component is associated with the ignition plug in actual. The piston 15 is reciprocated between a top dead center shown by a solid line in Fig. 1 where compression and explosion are performed and a bottom dead center shown by a phantom line in Fig. 1 where suction and exhaust are simultaneously performed.

[0031] A connecting member 21 is supported at one end thereof through a piston pin 17 to the piston 15. The other end of the connecting member 21 is forked to form two end portions 21a and 21b. Two cam followers 23 and 24 are fixedly connected to the two end portions 21a and 21b of the connecting member 21, respectively.

[0032] Two guide members 25 and 26 are fixed to the housing 20, and the two end portions 21a and 21b of the connecting member 21 are slidably engaged with the two guide members 25 and 26, respectively. That is, the two end portions 21a and 21b are linearly guided by the two guide members 25 and 26 in the same direction as a moving direction of the piston 15.

[0033] A drive shaft 30 is rotatably supported by two bearings 28 and 29 fixed in the housing 20. The drive shaft 30 is integrally formed with a cylindrical cam member 31 having a looped cam groove (cam) 31a to be hereinafter described. The cam followers 23 and 24 are slidably engaged with the cam groove 31a of the cylindrical cam member 31.

[0034] A gear 33 is fixedly mounted on the drive shaft 30. The gear 33 is in mesh with a gear 35 for taking out an output of the engine.

[0035] The left half of the power transmitting device 100 as viewed in Fig. 1 is similarly constructed. The same parts in the left half as those in the right half are denoted by the same reference numerals plus prime ('), and the explanation thereof will be omitted hereinafter.

[0036] In the power transmitting device 100, the drive shaft 30 is integrally formed at its opposite ends with the two cylindrical cam members 31 and 31', and the two cam grooves 31a and 31a' are formed on the cylindrical surfaces of the cam members 31 and 31', respectively. Thus, the power transmitting device 100 has the two cam grooves 31a and 31a' in accordance with the two cylinders 11 and 11' of the engine.

[0037] The cam groove 31a has a characteristic curve as shown in Fig. 3A. The characteristic curve shows a cam diagram wherein the relation between a displacement of the cam followers 23 and 24 and a rotational angle of the cylindrical cam member 31 is represented by orthogonal coordinates. The other cam groove 31a' has the same characteristic curve as that of the cam groove 31a.

[0038] Fig. 3B shows a development of the cam groove 31a formed on the cylindrical cam member 31 of the drive shaft 30. As apparent from Fig. 3B, the motion of the cam followers 23 and 24 relative to the cam groove 31a is a simple harmonic motion, and the displacement curve of the cam followers 23 and 24 is a sine curve. The cam having such a shape is satisfactory in performance regarding a pressure angle, and it is easy to carry out generating.

[0039] The characteristic curve of the cam mentioned above is illustrative, and various other characteristic curves may be adopted.

[0040] Figs. 4A, 4B and 4C illustrate a rotational force F_R of the cylindrical cam member 31 to be generated upon application of a force F to the cam groove 31a, wherein Fig. 4A corresponds to the case where an inclined angle of the cam groove 31a is less than 45° ; Fig. 4B corresponds to the case where the inclined angle is equal to 45° ; and Fig. 4C corresponds to the case where the inclined angle is greater than 45° .

[0041] At the center of the stroke of the piston 15, the inclined angle of the cam groove 31a is equal to 45° because the displacement curve is a sine curve as mentioned above.

[0042] Letting ϑ denote the inclined angle of the cam groove 31a, the rotational force F_R of the cylindrical cam member 31 is expressed as follows:


   When the inclined angle ϑ is equal to 45° , it is understood from the above expression that F_R becomes equal to F. Also apparent from Figs. 4A and 4C, when the inclined angle ϑ is less than 45° or greater than 45° , the rotational force F_R becomes less than that in the case where the inclined angle ϑ is equal to 45° shown in Fig. 4B.

[0043] The operation of the power transmitting device 100 will now be described. The description will be directed to the right half as viewed in Fig. 1 for the convenience.

[0044] A fuel-air mixture is supplied from a carburetor (not shown) into the cylinder 11 to repeatedly perform suction, compression, explosion and exhaust in the cylinder 11. As a result, the piston 15 in the cylinder 11 is reciprocated with a given stroke.

[0045] Accordingly, the connecting member 21 supported through the piston pin 17 to the piston 15 is also reciprocated by the reciprocation of the piston 15. In the course of the reciprocation of the connecting member 21, the end portions 21a and 21b of the connecting member 21 are linearly guided by the guide members 25 and 26 fixed to the housing 20 to reciprocate in the direction same as the moving direction of the piston 15.

[0046] Accordingly, the cam followers 23 and 24 supported to the end portions 21a and 21b of the connecting member 21 and slidably engaged with the cam groove 31a of the cylindrical cam member 31 are reciprocated to relatively travel in the cam groove 31a and thereby rotate the cylindrical cam member 31.

[0047] As shown in Fig. 3B, the cam groove 31a has a length four times the stroke of the piston 15, and has a period of 180° corresponding to twice the stroke. Accordingly, when the piston 15 is twice reciprocated, the drive shaft 30 integral with the cylindrical cam member 31 is once rotated. As a result, the gear 33 fixed to the drive shaft 30 is rotated to rotate the gear 35 meshing the gear 33, thereby transmitting the power of the engine to the outside through a shaft (not shown) of the gear 35 or a gearing (not shown) meshing the gear 35.

[0048] The left half of the power transmitting device 100 is also similarly operated.

[0049] The explosion in the cylinders 11 and 11' is performed at the same timing, so that the drive shaft 30 receives a torque twice that generated by each cylinder of the engine.

[0050] In a conventional reciprocating engine, a reciprocating motion of a piston is converted through a connecting rod to a rotational motion of a crank shaft.

[0051] To the contrary, in the power transmitting device 100, the reciprocating motion of the pistons 15 and 15' is converted through the connecting members 21 and 21' to the rotational motion of the drive shaft 30.

[0052] That is, the difference between the conventional reciprocating engine and the power transmitting device 100 is that while the conventional crank shaft is born and rotated about an axis on a plane perpendicular to a reciprocating direction of the piston, the drive shaft 30 in the power transmitting device 100 is born and rotated about an axis on a plane parallel to the reciprocating direction of the pistons 15 and 15'.

[0053] With this arrangement, the power transmitting device 100 can be made very compact in a radial direction of the cylinders 11 and 11' except a fuel supply system and an ignition system.

[0054] Further, the explosion in the two cylinders 11 and 11' opposed to each other is performed at the same timing to thereby eliminate action and reaction in an axial direction of the drive shaft 30, thereby eliminating undue vibration.

[0055] A reduction ratio in the power transmitting device 100 is decided according to the number of periods of the cam groove 31a or 31a' corresponding to the number of reciprocation of the piston 15 or 15' per rotation (360° ) of the cylindrical cam member 31 or 31' of the drive shaft 30. That is, when the number of reciprocation of the piston 15 or 15' per rotation of the drive shaft 30 is n (n: positive integer), the reduction ratio is identical with a gear ratio n.

[0056] It is now assumed that the number of periods of the cam groove 31a is 1 per rotation of the drive shaft 30.

[0057] Letting r, ϑ , x, y and S_t denote a radius of the cylindrical cam member 31, a rotational angle thereof, a circumferential moving distance thereof, a vertical displacement thereof, and a stroke of the piston 15, respectively, and assuming that the inclined angle of the cam groove 31a at the center of the stroke of the piston 15 is equal to 45° , the relation between the radius r and the stroke S_t is expressed as follows:














   In the above expression, x = 0 at the center of the stroke of the piston 15 is substituted to give





   Further, since the inclined angle of the cam groove 31a is equal to 45° at x = 0,

is given.





   Thus, under the condition that the inclined angle of the can groove 31a at the center of the stroke of the piston 15 is equal to 45° , the radius r of the cylindrical cam member 31 is equal to a value 1/2 times the stroke S_t of the piston 15.

[0058] Next, it is assumed that the number of periods of the cam groove 31a is n (n: positive integer) per rotation of the drive shaft 30.

[0059] Letting Θ denote a rotational angle (real angle) of the drive shaft 30, an operational angle ϑ of the cam groove 31a corresponding to the real angle Θ is expressed as follows:





   Letting r, x, y and S_t denote a radius of the cylindrical cam member 31, a circumferential moving distance thereof, a vertical displacement thereof, and a stroke of the piston 15, respectively, and assuming that the inclined angle of the cam groove 31a at the center of the stroke of the piston 15 is equal to 45° , the relation between the radius r and the stroke S_t is expressed as follows:














   In the above expression, x = 0 at the center of the stroke of the piston 15 is substituted to give





   Further, since the inclined angle of the cam groove 31a is equal to 45° at x = 0,

is given.





   Thus, under the condition that the inclined angle of the cam groove 31a at the center of the stroke of the piston 15 is equal to 45° , the radius r of the cylindrical cam member 31 is equal to a value n/2 times the stroke S_t of the piston 15.

[0060] In this manner, when the number of periods of the cam groove formed on the cylindrical cam member integral with the drive shaft is set to n (n: positive integer) per rotation of the drive shaft, the power transmitting device becomes equivalent a power transmitting device incorporating a primary reduction gear having a reduction ratio of 1/n.

[0061] However, since the power transmitting device 100 in this preferred embodiment includes the two cam grooves 31a and 31a', the number of periods of the cam grooves becomes 2n, and the reduction ratio accordingly becomes 1/2n.

[0062] While the cam engaging with the power transmitting device is formed as the cam groove in this preferred embodiment, the cam may be formed as a projection formed on the cylindrical surface according to the present invention.

[0063] Further, the cam is formed as the outer circumferential cam formed on the cylindrical surface in this preferred embodiment, the cam may be formed as an inner circumferential cam formed on the cylindrical surface according to the present invention. In this case, the power transmitting member is arranged inside the cylindrical member so as to engage the inner circumferential cam.

Second Preferred Embodiment

[0064] Referring to Figs. 5 and 6, there is shown a power transmitting device 200 according to a second preferred embodiment of the present invention. In Figs. 5 and 6, the same reference numerals as those shown in Fig. 1 denote the same or like parts, and the explanation thereof will be omitted hereinafter.

[0065] As shown in Fig. 6, the power transmitting device 200 includes a two-cycle six-cylinder engine, in which six cylinders are arranged around a cylindrical cam member 31 at circumferential equal intervals on one side of the cam member 31. In Fig. 5, two radially opposed ones of the six cylinders are shown in vertical section. In Figs. 5 and 6, engine associated parts other than pistons reciprocatably inserted in the respective cylinders are not shown.

[0066] As shown in Fig. 5, a pair of drive shafts 30 extend coaxially from the opposite end surfaces of the cylindrical cam member 31. Two radially opposed pistons 151 and 154 are arranged concentrically with respect to the cylindrical surface of the cam member 31. Two connecting members 211 and 214 are supported at their end portions to the pistons 151 and 154, respectively. Two guide members 251 and 254 are fixed to a housing 20, and the connecting members 211 and 214 are linearly guided by the guide members 251 and 254 in a reciprocating direction of the pistons 151 and 154, respectively.

[0067] Two cam followers 231 and 234 are supported at the other end portions of the connecting members 211 and 214, respectively. The cam followers 231 and 234 are slidably engaged with a cam groove 31a formed on the cylindrical cam member 31. Accordingly, the cam followers 231 and 234 are reciprocated by the connecting members 211 and 214, respectively, as sliding along the cam groove 31a.

[0068] The cam groove 31a has a cam diagram similar to that shown in Fig. 3B. That is, when the pistons 151 and 154 are twice reciprocated, the cylindrical cam member 31 is once rotated. Accordingly, the drive shafts 30 integral with the cam member 31 are rotated as in a direction depicted by an arrow B in Fig. 5 to transmit a power to the outside.

[0069] In the power transmitting device 200, explosion in each cylinder of the engine occurs twice at equal intervals (180° ) per rotation of the drive shafts 30, and totally, the explosion in the six cylinders occurs twelve times per rotation of the drive shafts 30, so that a high torque can be smoothly obtained.

[0070] Further, since the six cylinders of the engine are arranged concentrically with the drive shafts 30, the structure of the power transmitting device 200 in the radial direction can be made compact.

[0071] Further, since the drive shafts 30 extend from the opposite end surfaces of the cylindrical cam member 31, the output can be taken out on the opposite sides of the power transmitting device 200 in the axial direction.

Third Preferred Embodiment

[0072] Referring to Fig. 7, there is shown a power transmitting device 300 according to a third preferred embodiment of the present invention. In Fig. 7, the same reference numerals as those shown in Fig. 5 denote the same or like parts, and the explanation thereof will be omitted hereinafter.

[0073] As similar to Fig. 6, the power transmitting device 300 includes a two-cycle six-cylinder engine, in which six cylinders are arranged around a cylindrical cam member 31 at circumferential equal intervals on the opposite sides of the cam member 31. In Fig. 7, two radially opposed ones of the six cylinders are shown in vertical section. In Fig. 7, engine associated parts other than pistons reciprocatably inserted in the respective cylinders are not shown.

[0074] As shown in Fig. 7, a pair of drive shafts 30 extend coaxially from the opposite end surfaces of the cylindrical cam member 31. Two radially opposed pistons 151 and 154 are arranged concentrically with respect to the cylindrical surface of the cam member 31. However, the third preferred embodiment differs from the second preferred embodiment in the point that the six cylinders are arranged alternately on the opposite sides of the cylindrical cam member 31.

[0075] In this manner, a plurality of cylinders may be suitably arranged with a high degree of freedom of design.

Fourth Preferred Embodiment

[0076] Referring to Figs. 8 and 9, there is shown a power transmitting device 400 according to a fourth preferred embodiment of the present invention. In Figs. 8 and 9, the same reference numerals as those shown in Fig. 5 denote the same or like parts, and the explanation thereof will be omitted hereinafter.

[0077] As shown in Figs. 8 and 9, the power transmitting device 400 includes a two-cycle twelve-cylinder engine, in which twelve cylinders are arranged around a cylindrical cam member 31 at circumferential equal intervals on the opposite sides of the cam member 31. In Fig. 8, four radially opposed ones of the twelve cylinders are shown in vertical section. In Figs. 8 and 9, engine associated parts other than pistons reciprocatably inserted in the respective cylinders are not shown.

[0078] Twelve pistons 151, 151', 152, 152', 153, 153', 154, 154', 155, 155', 156 and 156' are connected to twelve connecting members 211, 211', 212, 212', 213, 213', 214, 214', 215, 215', 216 and 216', respectively. That is, all the pistons 151 to 156' are individually connected to the respective connecting members 211 to 216'.

[0079] As shown in Fig. 8, a pair of drive shafts 30 extend coaxially from the opposite end surfaces of the cylindrical cam member 31. The two radially opposed pistons 151 and 154 are arranged concentrically with respect to the cylindrical surface of the cam member 31. Similarly, the two radially opposed pistons 151' and 154' are arranged concentrically with respect to the cylindrical surface of the cam member 31. That is, the connecting members 211 and 214 are arranged symmetrically with respect to the cam member 31 in relation to a cam groove 31a. Similarly, the connecting members 211' and 214' are arranged symmetrically with respect to the cam member 31 in relation to a cam groove 31a'.

[0080] Each of the cam grooves 31a and 31a' has a cam diagram similar to that shown in Fig. 3B. The cam grooves 31a and 31a' are formed on the cam member 31 so as to be symmetrical with each other in such a manner that the two axially opposed pistons 151 and 151' simultaneously come to their top dead centers or their bottom dead centers and that the two axially opposed pistons 154 and 154' simultaneously come to their top dead centers or their bottom dead centers.

[0081] Accordingly, when explosion occurs in the cylinders of the engine, the pistons 151 and 151' are moved in opposite directions to linearly move the connecting members 211 and 211' toward to each other and away from each other. Thus, the connecting members 211 and 211' are reciprocated in the directions as depicted by arrows C and C' in Fig. 8, respectively. Similarly, the connecting members 214 and 214' are reciprocated in the directions as depicted by arrows D and D' in Fig. 8, respectively. The reciprocation of the connecting members 211, 211', 214 and 214' makes rotation of the cylindrical cam member 31 by sliding engagement of cam followers 231 and 234 with the cam groove 31a and by sliding engagement of cam followers 231' and 234' with the cam groove 31a'. As a result, the drive shafts 30 integral with the cylindrical cam member 31 is rotated as in a direction depicted by an arrow B in Fig. 8.

[0082] In the power transmitting device 400, explosion in each cylinder of the engine occurs twice at equal intervals (180° ) per rotation of the drive shafts 30, and totally, the explosion in the twelve cylinders occurs twenty-four times per rotation of the drive shafts 30, so that a high torque can be very smoothly obtained.

[0083] Further, since the twelve cylinders of the engine are arranged concentrically with the drive shafts 30, the structure of the power transmitting device 400 in the radial direction can be made compact.

[0084] Further, since the explosion in the axially opposed cylinders is performed at the same timing, action and reaction in the axial direction of the drive shafts 30 can be eliminated to thereby eliminate undue vibration.

[0085] Further, since the drive shafts 30 extend from the opposite end surfaces of the cylindrical cam member 31, the output can be taken out on the opposite sides of the power transmitting device 400 in the axial direction.

Fifth Preferred Embodiment

[0086] Referring to Figs. 10 and 11, there is shown a power transmitting device 500 according to a fifth preferred embodiment of the present invention. In Figs. 10 and 11, the same reference numerals as those shown in Fig. 8 denote the same or like parts, and the explanation thereof will be omitted hereinafter.

[0087] As shown in Figs. 10 and 11, the power transmitting device 500 includes a two-cycle twelve-cylinder engine, in which twelve cylinders are arranged around a cylindrical cam member 31 at circumferential equal intervals on the opposite sides of the cam member 31. In Fig. 10, four radially opposed ones of the twelve cylinders are shown in vertical section. In Figs. 10 and 11, engine associated parts other than pistons reciprocatably inserted in the respective cylinders are not shown.

[0088] Six pairs of axially opposed pistons 151, 151'; 152, 152'; 153, 153'; 154, 154'; 155, 155'; and 156, 156' are connected to six connecting members 211, 212, 213, 214, 215, and 216, respectively. That is, each pair of axially opposed pistons is connected to a common connecting member.

[0089] As shown in Fig. 10, a pair of drive shafts 30 extend coaxially from the opposite end surfaces of the cylindrical cam member 31. The two radially opposed pistons 151 and 154 are arranged concentrically with respect to the cylindrical surface of the cam member 31. Similarly, the two radially opposed pistons 151' and 154' are arranged concentrically with respect to the cylindrical surface of the cam member 31. That is, the connecting members 211 and 214 are arranged symmetrically with respect to the cam member 31 in relation to a cam groove 31a. The cam groove 31a has a cam diagram similar to that shown in Fig. 3B. The cam groove 31a is formed on the cam member 31 in such a manner that when the pistons 151 and 154 come to their top dead centers, the pistons 151' and 154' come to their bottom dead centers, while in contrast, when the pistons 151 and 154 come to their bottom dead centers, the pistons 151' and 154' come to their top dead centers.

[0090] Accordingly, when explosion occurs in the cylinders of the engine, the pistons 151 and 151' are moved in the same direction to linearly move the connecting member 211 in this direction. Thus, the connecting members 211 is reciprocated in the direction as depicted by an arrow C in Fig. 10. Similarly, the connecting member 214 is reciprocated in the direction as depicted by an arrow D in Fig. 10. The reciprocation of the connecting members 211 and 214 makes rotation of the cylindrical cam member 31 by sliding engagement of cam followers 231 and 234 with the cam groove 31a. As a result, the drive shafts 30 integral with the cylindrical cam member 31 is rotated as in a direction depicted by an arrow B in Fig. 10.

[0091] In the power transmitting device 500, explosion in each cylinder of the engine occurs twice at equal intervals (180° ) per rotation of the drive shafts 30, and totally, the explosion in the twelve cylinders occurs twenty-four times per rotation of the drive shafts 30, so that a high torque can be very smoothly obtained.

[0092] Further, since the twelve cylinders of the engine are arranged concentrically with the drive shafts 30, the structure of the power transmitting device 500 in the radial direction can be made compact.

[0093] Further, since the drive shafts 30 extend from the opposite end surfaces of the cylindrical cam member 31, the output can be taken out on the opposite sides of the power transmitting device 500 in the axial direction.

[0094] In the first to fifth preferred embodiments mentioned above, each power transmitting device employs a two-cycle engine having a simple structure not requiring a suction valve and an exhaust valve. However, a four-cycle engine requiring a suction valve and an exhaust valve may be employed, of course. In this case, an output end of each drive shaft in the second to fifth preferred embodiments may be utilized for control of the suction and exhaust valves. Accordingly, as compared with a conventional engine, greatly accurate control of the suction and exhaust valves with less timing error can be effected because the output shaft is present near the suction and exhaust valves.

Sixth Preferred Embodiment

[0095] Referring to Fig. 12, there is shown a power transmitting device 600 according to a sixth preferred embodiment of the present invention. In Fig. 12, the same reference numerals as those shown in Fig. 1 denote the same or like parts, and the explanation thereof will be omitted hereinafter. A cross section taken along the line A-A in Fig. 12 is identical with that shown in Fig. 2, and it is therefore not shown. In particular, the structure of a cylinder, piston, cam and cam follower is the same as that shown in Fig. 1.

[0096] As shown in Fig. 12, the power transmitting device 600 has a one-cylinder two-cycle engine. A drive shaft 30 extends from one end surface of a cylindrical cam member 31 having a cam groove 31a. A rotor 35 is fixedly mounted on an output end portion 33 of the drive shaft 30 by using any tightening means. The rotor 35 is integrally formed with a cooling fan.

[0097] The cooling fan may be replaced by a rotary blade to be applied to a mowing machine. Further, a drill may be mounted on the output end portion 33 of the drive shaft 30 to be applied to a drilling machine. Further, a screw may be mounted on the output end portion 33 of the drive shaft 30 to be applied to a motorboat engine.

Seventh Preferred Embodiment

[0098] Referring to Figs. 13 and 14, there is shown a power transmitting device 700 according to a seventh preferred embodiment of the present invention. The arrangement of cylinders, pistons, connecting members, cam followers and cams is substantially the same as that in the fifth preferred embodiment shown in Fig. 10.

[0099] The power transmitting device 700 has a four-cycle twelve-cylinder engine, in which twelve cylinders are arranged around a cylindrical cam member 31 at circumferential equal intervals on the opposite sides of the cam member 31. The twelve cylinders are constructed as six pairs of cylinder, the cylinders of each pair being opposed to each other in an axial direction of the cylindrical cam member 31 and being symmetrical with each other with respect to the cam member 31.

[0100] Six pairs of axially opposed pistons 151, 151'; 152, 152'; 153, 153'; 154, 154'; 155, 155'; and 156, 156' are connected to six connecting members 211, 212, 213, 214, 215 and 216, respectively. That is, each pair of axially opposed pistons in the opposed cylinders is connected to a common connecting member.

[0101] In Fig. 13, four radially opposed ones of the twelve cylinders are shown in vertical section. As shown in Fig. 13, a pair of drive shafts 30 extend coaxially from the opposite end surfaces of the cylindrical cam member 31. The two radially opposed pistons 151 and 154 are arranged concentrically with respect to the cylindrical surface of the cam member 31. Similarly, the two radially opposed pistons 151' and 154' are arranged concentrically with respect to the cylindrical surface of the cam member 31. That is, the connecting members 211 and 214 are arranged symmetrically with respect to the cam member 31 in relation to a cam groove 31a.

[0102] Four cylinders 111, 111', 114 and 114' respectively receiving the pistons 151, 151', 154 and 154' are fixed to a housing 20.

[0103] The four cylinders 111 to 114' are basically identical in construction with each other. Accordingly, the construction of the cylinder 111 only will now be described for convenience.

[0104] An ignition plug S_p is threadedly engaged with a cylinder head of the cylinder 111 at a central portion thereof. Any parts of an electrical system to be connected with the ignition plug S_p are not shown.

[0105] The cylinder head is formed with a suction port 111a for introducing a fuel-air mixture supplied from a carburetor (not shown) into the cylinder 111 and with an exhaust port 111b for discharging an exhaust gas from the cylinder 111. A suction valve 261 for opening and closing the suction port 111a and an exhaust valve 281 for opening and closing the exhaust port 111b are movably supported to the cylinder head.

[0106] The suction valve 261 is normally biased by a spring 263 so as to close the suction port 111a, and the exhaust valve 281 is normally biased by a spring 283 so as to close the exhaust port 111b. A spring retainer 265 is fixed to an outer end of the suction valve 261, and a spring retainer 285 is fixed to an outer end of the exhaust valve 281. A roller 271 is rotatably supported to the spring retainer 265, and a roller 291 is rotatably supported to the spring retainer 285.

[0107] A rotary cam member 40 as a valve operating member is fixed to each drive shaft 30, and two projection cams are concentrically formed on the rotary cam member 40 for each cylinder in such a manner as to alternatively depress the rollers 271 and 291.

[0108] When the pistons 151 and 154 are in the positions of their top dead centers in an exhaust stroke and a compression stroke as shown in Fig. 13, the pistons 151' and 154' are in the positions of their bottom dead centers in a suction stroke and an explosion stroke. Conversely, when the pistons 151 and 154 are in the positions of their bottom dead centers, the pistons 151' and 154' are in the positions of their top dead centers. In this manner, the pistons 151 and 151' are reciprocated so as to simultaneously take the top dead center and the bottom dead center, respectively. At the same time, the pistons 154 and 154' are reciprocated so as to simultaneously take the top dead center and the bottom dead center, respectively.

[0109] The connecting member 211 supported at its opposite ends to the pistons 151 and 151' is linearly guided by a guide member 251 fixed to the housing 20 to reciprocate in the direction same as the reciprocating direction of the pistons 151 and 151' as depicted by an arrow C in Fig. 13. Similarly, the connecting member 214 supported at its opposite ends to the pistons 154 and 154' is linearly guided by a guide member 254 fixed to the housing 20 to reciprocate in the direction same as the reciprocating direction of the pistons 154 and 154' as depicted by an arrow D in Fig. 13.

[0110] Cam followers 231 and 234 as the power transmitting member are supported to the connecting members 211 and 214 at their central portions, respectively.

[0111] The cam followers 231 and 234 are slidably engaged with a cam groove 31a formed on the cylindrical cam member 31 integral with the drive shaft 30.

[0112] The cam groove 31a is formed as similar to that of the fifth preferred embodiment.

[0113] The operation of the power transmitting device 700 will now be described. The description will be directed to the construction shown in Fig. 13 for the convenience.

[0114] A fuel-air mixture is supplied from a carburetor (not shown) into the cylinders 111, 111' , 114 and 114' to repeatedly perform suction, compression, explosion and exhaust in the cylinders 111 to 114'. As a result, the pistons 151, 151', 154 and 154' in the cylinders 111, 111', 114 and 114' are reciprocated with a given stroke.

[0115] Accordingly, the connecting members 211 and 214 respectively supported to the pistons 151, 151' and 154, 154' are also reciprocated by the reciprocation of the respective pistons. In the course of the reciprocation of the connecting members 211 and 214, the connecting members 211 and 214 are linearly guided by the guide members 251 and 254 fixed to the housing 20 to reciprocate in the direction same as the moving direction of the respective pistons.

[0116] Accordingly, the cam followers 231 and 234 supported to the connecting members 211 and 214 and slidably engaged with the cam groove 31a of the cylindrical cam member 31 are reciprocated to relatively travel in the cam groove 31a and thereby rotate the cylindrical cam member 31.

[0117] As shown in Fig. 3B, the cam groove 31a has a length four times the stroke of each piston, and has a period of 180° corresponding to twice the stroke. Accordingly, when each piston is twice reciprocated, the drive shafts 30 integral with the cylindrical cam member 31 is once rotated. As a result, the power of the engine is transmitted to the outside by the rotation of the drive shafts 30.

[0118] Accordingly, when explosion occurs in the cylinders 111 and 111' of the engine, the pistons 151 and 151' are moved in the same direction to linearly move the connecting member 211 in this direction. Thus, the connecting member 211 is reciprocated in the direction as depicted by the arrow C in Fig. 13. Similarly, the connecting member 214 is reciprocated in the direction as depicted by the arrow D in Fig. 13. The reciprocation of the connecting members 211 and 214 makes rotation of the cylindrical cam member 31 by sliding engagement of the cam followers 231 and 234 with the cam groove 31a. As a result, the drive shafts 30 integral with the cylindrical cam member 31 is rotated as in a direction depicted by an arrow B in Fig. 13.

[0119] In the power transmitting device 700, explosion in each cylinder of the engine occurs once at equal intervals (360° ) per rotation of the drive shafts 30, and totally, the explosion in the twelve cylinders occurs twelve times per rotation of the drive shafts 30, so that a high torque can be very smoothly obtained.

[0120] Further, since the twelve cylinders of the engine are arranged concentrically with the drive shafts 30, the structure of the power transmitting device 700 in the radial direction can be made compact.

[0121] Further, the ignition plug to be engaged with each cylinder head is desirably arranged with a high degree of freedom. Accordingly, it is easy to arrange the ignition plug at the central portion of each cylinder head as in Fig. 13. Thus, a best ignition condition to the fuel-air mixture in the cylinder can be set by suitably selecting the position of the ignition plug.

[0122] Further, since the drive shafts 30 extend from the opposite end surfaces of the cylindrical cam member 31, the output can be taken out on the opposite sides of the power transmitting device 700 in the axial direction.

[0123] Referring to Fig. 15 which is a cross section taken along the line E-E in Fig. 13, reference numeral 411 denotes a projection cam formed on the rotary cam member 40 for operating the exhaust valve 281. In the cylinder 111 shown in Fig. 15, the roller 291 of the exhaust valve 281 is depressed by the projection cam 411 of the rotary cam member 40 to open the exhaust port 111b. In this condition, the piston 151 is in the position of the top dead center to perform exhaust.

[0124] When the rotary cam member 40 is rotated at 90° from the above exhaust position (angle) to a suction position, the roller 271 of the suction valve 261 is similarly depressed by another projection cam (not shown) formed on the rotary cam member 40 to open the suction port 111a. In this condition, the piston 151 is in the position of the bottom dead center.

[0125] Thus, the two projection cams for performing the suction and the exhaust in each cylinder are formed on the rotary cam member 40 in concentric relationship with each other.

[0126] The operation of the suction and exhaust valves is directly controlled by the rotary cam member 40 fixed to each drive shaft 30, thereby reducing a timing error.

[0127] Further, the two projection cams for operating the suction and exhaust valves in one cylinder can be commonly used for the operation of the suction and exhaust valves in the other cylinders by the rotation of the rotary cam member 40.

[0128] Further, the sequence of explosion in the cylinders on the same side with respect to the cylindrical cam member 31 may be changed, for example, by changing the position of the suction valve or the exhaust valve into a position rotated by a certain angle about the position of the ignition plug and accordingly changing the position of the projection cam so as to correspond to the position of the roller of the suction valve or the exhaust valve changed in position.

Eighth Preferred Embodiment

[0129] Referring to Fig. 16, there is shown a power transmitting device 800 according to an eighth preferred embodiment of the present invention. The arrangement of cylinders, pistons, connecting members, cam followers and cams is substantially the same as that in the second preferred embodiment shown in Fig. 5.

[0130] The power transmitting device 800 has a four-cycle six-cylinder engine, in which six cylinders are arranged around a cylindrical cam member 31 at circumferential equal intervals on one side of the cam member 31.

[0131] In Fig. 16, two radially opposed ones of the six cylinders are shown in vertical section. As shown in Fig. 16, a pair of drive shafts 30 extend coaxially from the opposite end surfaces of the cylindrical cam member 31. The two radially opposed pistons 151 and 154 are arranged concentrically with respect to the cylindrical surface of the cam member 31.

[0132] A rotary cam member 40 as a valve operating member is fixed to each drive shaft 30, and two projection cams are concentrically formed on the rotary cam member 40 for each cylinder in such a manner as to alternatively depress the rollers 271 and 291.

[0133] In the power transmitting device 800, explosion in each cylinder of the engine occurs once at equal intervals (360° ) per rotation of the drive shafts 30, and totally, the explosion in the six cylinders occurs six times per rotation of the drive shafts 30, so that a high torque can be smoothly obtained.

[0134] Further, since the six cylinders of the engine are arranged concentrically with the drive shafts 30, the structure of the power transmitting device 800 in the radial direction can be made compact.

[0135] Further, an ignition plug S_p to be engaged with each cylinder head is desirably arranged with a high degree of freedom. Accordingly, it is easy to arrange the ignition plug S_p at the central portion of each cylinder head as in Fig. 16. Thus, a best ignition condition to the fuel-air mixture in the cylinder can be set by suitably selecting the position of the ignition plug S_p.

[0136] Further, since the drive shafts 30 extend from the opposite end surfaces of the cylindrical cam member 31, the output can be taken out on the opposite sides of the power transmitting device 800 in the axial direction.

[0137] In the cylinder 111 shown in Fig. 16, the roller 271 of the suction valve 261 is depressed by a projection cam 421 of the rotary cam member 40 to open the suction port 111a. In this condition, the piston 151 is in the position of the bottom dead center to perform suction.

[0138] Thus, the two projection cams for performing the suction and the exhaust in each cylinder are formed on the rotary cam member 40 in concentric relationship with each other.

[0139] The operation of the suction and exhaust valves is directly controlled by the rotary cam member 40 fixed to each drive shaft 30, thereby reducing a timing error.

[0140] Further, the two projection cams for operating the suction and exhaust valves in one cylinder can be commonly used for the operation of the suction and exhaust valves in the other cylinders by the rotation of the rotary cam member 40.

Ninth Preferred Embodiment

[0141] Referring to Fig. 17, there is shown a power transmitting device 900 according to a ninth preferred embodiment of the present invention. The arrangement of cylinders, pistons, connecting members, cam followers and cams is substantially the same as that in the fourth preferred embodiment shown in Fig. 8.

[0142] The power transmitting device 900 has a four-cycle twelve-cylinder engine, in which twelve cylinders are arranged around a cylindrical cam member 31 at circumferential equal intervals on the opposite sides of the cam member 31. Pistons 151, 151', 154 and 154' are connected to connecting members 211, 211', 214 and 214', respectively. That is, all the pistons are individually connected to the respective connecting members.

[0143] In the power transmitting device 900, explosion in each cylinder of the engine occurs once at equal intervals (360° ) per rotation of the drive shafts 30, and totally, the explosion in the twelve cylinders occurs twelve times per rotation of the drive shafts 30, so that a high torque can be very smoothly obtained.

[0144] Further, since the explosion in the axially opposed cylinders is performed at the same timing, action and reaction in the axial direction of the drive shafts 30 can be eliminated to thereby eliminate undue vibration.

[0145] Further, since the twelve cylinders of the engine are arranged concentrically with the drive shafts 30, the structure of the power transmitting device 900 in the radial direction can be made compact.

[0146] Further, an ignition plug S_p to be engaged with each cylinder head is desirably arranged with a high degree of freedom. Accordingly, it is easy to arrange the ignition plug S_p at the central portion of each cylinder head as in Fig. 17. Thus, a best ignition condition to the fuel-air mixture in the cylinder can be set by suitably selecting the position of the ignition plug S_p.

[0147] Further, since the drive shafts 30 extend from the opposite end surfaces of the cylindrical cam member 31, the output can be taken out on the opposite sides of the power transmitting device 900 in the axial direction.

[0148] In the cylinder 111 shown in Fig. 17, neither the roller 271 of the suction valve 261 nor the roller 291 of the exhaust valve 281 is depressed by the projection cam 411 of the rotary cam member 40 to close both the suction port 111a and the exhaust port 111b. In this condition, the piston 151 is in the position of the top dead center to perform compression.

[0149] Thus, the two projection cams for performing the suction and the exhaust in each cylinder are formed on the rotary cam member 40 in concentric relationship with each other.

[0150] The operation of the suction and exhaust valves is directly controlled by the rotary cam member 40 fixed to each drive shaft 30, thereby reducing a timing error.

[0151] Further, the two projection cams for operating the suction and exhaust valves in one cylinder can be commonly used for the operation of the suction and exhaust valves in the other cylinders by the rotation of the rotary cam member 40.

[0152] While the invention has been described with reference to specific embodiments, the description is illustrative and is not to be construed as limiting the scope of the invention. Various modifications and changes may occur to those skilled in the art without departing from the spirit and scope of the invention as defined by the appended claims.

[0153] A power transmitting device for converting a reciprocating motion of a piston into a rotational motion. The piston is reciprocated in a cylinder of a reciprocating engine to perform suction, compression, explosion and exhaust. The power transmitting device includes a connecting member supported to the piston; a guide member for linearly guiding the connecting member; a power transmitting member supported to the connecting member; a cam member having a cylindrical surface on which a cam having a predetermined cam curve is formed, the cam being engaged with the power transmitting member; and a drive shaft integral with the cam member. The drive shaft is rotated by a linear reciprocating motion of the power transmitting member in a plane perpendicular to a direction of the linear reciprocating motion of the power transmitting member. With this arrangement, the drive shaft extends in a direction parallel to a reciprocating direction of the piston, thereby making the construction of the power transmitting device greatly compact in a radial direction thereof. Further, the power transmitting device is equivalent to a power transmitting device including a primary reduction gear having a reduction ratio to be decided by the cam curve of the cam, thereby smoothly obtaining a high torque.

Claims

1. A power transmitting device for converting a reciprocating motion of a piston into a rotational motion, said piston being reciprocated in a cylinder of a reciprocating engine to perform suction, compression, explosion and exhaust; said power transmitting device comprising:
   a connecting member supported to said piston;
   a guide member for linearly guiding said connecting member;
   a power transmitting member supported to said connecting member;
   a cam member having a cylindrical surface on which a cam having a predetermined cam curve is formed, said cam being engaged with said power transmitting member; and
   a drive shaft integral with said cam member, said drive shaft being rotated by a linear reciprocating motion of said power transmitting member in a plane perpendicular to a direction of said linear reciprocating motion of said power transmitting member.

2. The power transmitting device as defined in claim 1, wherein said engine has a plurality of cylinders opposed to each other in an axial direction of said cam member.

3. The power transmitting device as defined in claim 1, wherein said engine has a plurality of cylinders arranged concentrically with respect to an axis of said cam member so as to extend in a direction parallel to said axis of said cam member.

4. The power transmitting device as defined in claim 1, wherein said engine has a plurality of cylinders opposed to each other in an axial direction of said cam member and arranged concentrically with respect to an axis of said cam member so as to extend in a direction parallel to said axis of said cam member.

5. The power transmitting device as defined in claim 1, wherein said engine has a plurality of pairs of cylinders, said cylinders of each pair being axially opposed to each other;
   said connecting member is supported at opposite ends thereof to pistons received in said cylinders of each pair; and
   said plurality of pairs of cylinders are arranged concentrically with respect to an axis of said cam member so as to extend in a direction parallel to said axis of said cam member.

6. The power transmitting device as defined in claim 1, wherein said engine comprises a four-cycle engine having a plurality of cylinders arranged concentrically with respect to an axis of said cam member so as to extend in a direction parallel to said axis of said cam member;
   said connecting member is supported at one end thereof to a piston received in each of said cylinders; and
   said power transmitting device further comprises a suction valve and an exhaust valve provided at a head portion of said each cylinder, and a valve operating member fixed to said drive shaft and having a plate-like form expanding in a direction perpendicular to an axis of said drive shaft, for controlling start and end of operation of said suction valve in a suction stroke in said each cylinder and said exhaust valve in an exhaust stroke in said each cylinder in association with rotation of said drive shaft, said valve operating member having at least two cams adapted to engage said suction valve in an axial direction thereof and said exhaust valve in an axial direction thereof, respectively.

7. The power transmitting device as defined in claim 1, wherein said engine comprises an internal combustion engine.

8. The power transmitting device as defined in claim 2, wherein said engine comprises an internal combustion engine.

9. The power transmitting device as defined in claim 3, wherein said engine comprises an internal combustion engine.

10. The power transmitting device as defined in claim 4, wherein said engine comprises an internal combustion engine.

11. The power transmitting device as defined in claim 5, wherein said engine comprises an internal combustion engine.

12. The power transmitting device as defined in claim 6, wherein said engine comprises an internal combustion engine.

Drawing