Intake system of engine

Abstract

 Problem
An object of the present invention is to realize a compact formation of an intake system by unitizing a throttle position sensor and a fuel injection controlling elements and mounting unitized one on a throttle body in a compact manner.
Solution
In an intake system provided with a throttle body 11 having an intake path 12 communicating with an intake port of an engine E, with a throttle valve 20 for controlling an intake quantity of the engine by means of the intake path 12, and with a fuel injection valve 9 for injecting fuel and supplying to the engine E, the throttle body 11 is mounted with an electronic controlling unit U integrated with a throttle position sensor Sth for detecting an opening degree of the throttle valve 20 and with a fuel injection controlling elements 81 and 82 for controlling fuel injection quantity of the fuel injection valve 9 on the basis of, at least, an output signal of the throttle position sensor Sth.

Description

Field of the Invention

[0001] The present invention relates to an improvement in an intake system of an engine provided with a throttle body having an intake path communicating with an intake port of the engine, with a throttle valve for controlling an intake quantity of the engine by means of the intake path, and with an fuel injection valve for injecting fuel to be supplied to the engine.

Prior Art

[0002] Such an intake system of an engine has already been known as disclosed, for example, in Japanese Unexamined Utility Model Publication NO. H3-122268.

Problems to be Solved by the Invention

[0003] In such a conventional intake system, since a throttle position sensor for detecting an opening degree of the throttle valve is provided on the throttle body and fuel injection control elements for controlling a fuel injection quantity of the fuel injection valve are provided on an electronic control unit to be installed in a portion different from the throttle body respectively, spaces for installing the throttle position sensor and the electronic control unit respectively must be secured individually, thus space efficiency is poor and compact formation of the intake system is difficult, besides, since wiring operation is needed in a space between the throttle position sensor and the electronic control unit, there poses a problem that assembling man-hour in accordance therewith is required.

[0004] The object of the present invention is to provide an intake system of the engine in which such problems can be resolved at a stroke.

Means for Solving the Problem

[0005] In order to achieve the object described above, according to a first aspect of the present invention, there is provided in an intake system of an engine including a throttle body having an intake path communicating with an intake port of the engine, a throttle valve for controlling an intake quantity of the engine by means of the intake path, and a fuel injection valve for injecting fuel to be supplied to the engine, the throttle body mounted with an electronic control unit integrated with a throttle position sensor for detecting an opening degree of the throttle valve and fuel injection control elements for controlling a fuel injection quantity of the fuel injection valve at least on the basis of an output signal of the throttle position sensor. Further, the fuel injection control elements described above correspond to a fuel injection quantity control element 81 and a fuel injection timing control element 82 in embodiments of the present invention which will be described later.

[0006] According to the first aspect, the throttle position sensor and the fuel injection control elements are unitized and can be mounted on the throttle body in a compact manner, accordingly, it becomes unnecessary to prepare an installation space for the electronic control unit other than the throttle body, space efficiency is improved and compact formation of the intake system can be realized. Further, simplification of wiring in a space between the throttle position sensor and the fuel injection control elements is also possible to be realized.

[0007] Further, in addition to the aspect described above, according to a second aspect of the present invention the throttle position sensor is constituted of a rotor rotating in cooperation with an opening degree of the throttle valve and of a stator opposed to the rotor for converting a rotating angle of the rotor into an electric signal, the stator is provided on a sensor board of the electronic control unit, and the fuel injection control elements are arranged on a back face side of the sensor board on an opposite side of the throttle position sensor .

[0008] According to the second aspect, the fuel injection control elements are possible to be freely arranged on a large back face side of the sensor board and a layout design can be conducted as desired.

[0009] Further, in addition to the first and second aspects, according to a third aspect of the present invention, the throttle body is made of a synthetic resin.

[0010] According to the third aspect of the present invention, since the throttle body itself is imparted an insulating property, the electronic control unit can be mounted on the throttle body without interposing a special insulating member, thus simplification of a mounting structure is possible to be realized.

[0011] Furthermore, in addition to any one of the first to third aspects, according to fourth aspect of the present invention, the electronic control unit is further integrated with an ignition timing control element for controlling ignition timing of the engine.

[0012] According to the fourth aspect of the present invention, not only the throttle position sensor and the fuel injection control elements but also the ignition timing control element are unitized and can be mounted on the throttle body in a compact manner, thus simplification of an engine control system is possible to be realized.

Brief Description of the Drawings

[0013] Embodiments of the present invention will be described hereinafter on the basis of an embodiment of the present invention illustrated in the attached drawings, wherein :

Fig. 1 shows a vertical sectional side view illustrating an engine provided with an intake quantity control device according to a first embodiment of the present invention,

Fig. 2 shows a side view illustrating the intake quantity control device,

Fig. 3 shows a sectional view taken along the line 3-3 of Fig. 2,

Fig. 4 shows an exploded view corresponding to Fig. 3,

Fig. 5 shows a sectional view taken along the line 5-5 of Fig. 3,

Fig. 6 shows a sectional view taken along the line 6-6 of Fig. 3,

Fig. 7 shows a sectional view taken along the line 7-7 of Fig. 3,

Fig. 8 shows a view describing the operation of a throttle valve,

Fig. 9 shows a diagrammatic view of characteristic illustrating an intake quantity control device of the present invention,

Fig. 10 shows a sectional view corresponding to Fig. 8 illustrating a second embodiment of the present invention, and

Fig. 11 shows a sectional view corresponding to Fig. 8 illustrating a third embodiment of the present invention.

Embodiments of the Invention

[0014] Fig. 1-Fig. 9 illustrate a first embodiment of the present invention, Fig. 1 shows a vertical sectional side elevation view illustrating an engine provided with an intake quantity control device of the present invention, Fig. 2 shows a side elevation view illustrating an intake quantity control device of the present invention, Fig. 3 shows a sectional view taken substantially along the line 3-3 of Fig. 2, Fig. 4 shows an exploded view corresponding to Fig. 3, Fig. 5 shows a sectional view taken substantially along the line 5-5 of Fig. 3, Fig. 6 shows a sectional view taken substantially along the line 6-6 of Fig. 3, Fig. 7 shows a sectional view taken substantially along the line 7-7 of Fig. 3, Fig. 8 shows a view describing the operation of a throttle valve, Fig. 9 shows a diagrammatic view illustrating characteristics of an intake quantity control device of the present invention, Fig. 10 shows a sectional view corresponding to Fig. 8 illustrating a second embodiment of the present invention, and Fig. 11 shows a sectional view corresponding to Fig. 8 illustrating a third embodiment of the present invention.

[0015] First, a first embodiment of the present invention will be described. In Fig. 1, an engine E is a four cycle engine for a motorcycle, is provided with a cylinder block 1 and a cylinder head 2, and is in a substantially horizontal position directing head section thereof forward of a vehicle, further the cylinder head 2 is provided with an intake port 3, exhaust port 4, intake valve 5, exhaust valve 6 and a valve system 7 open/close driving these valves. An intake tube 8 communicating with the intake port 3 is joined on an upper surface of the cylinder head 2. The intake tube 8 is made of synthetic resin and on a support boss 8c formed on one side thereof, an electromagnetic fuel injection valve 9 is mounted by means of a valve holder 91. Injection fuel injected from the fuel injection valve 9 is to be directed to the intake port 3 of the cylinder head 2 through a fuel discharge hole 96 formed in the intake tube 8.

[0016] The valve holder 91 is integrally molded out of synthetic resin and is composed of a first holding cylinder section 91a fitted on a base of the fuel injection valve 9, of a second holding cylinder section 91b fitted on a tip end section having a fuel inlet of the injection valve 9, of a coupling section 91c integrally connecting between both the holding cylinder sections 91a and 91b, and of a hose joint 92 projecting from one side of the second holding cylinder section 91b, and in the first holding cylinder section 91a, a metal made ring 93 for connecting with the support boss 8c described above is embedded. A fuel hose 94 communicating with a fuel injection pump, not illustrated, is connected with the hose joint 92.

[0017] An intake quantity control device 10 is connected with an upstream end of the intake tube 8 on which the fuel injection valve 9 is mounted. That is, the intake quantity control device 10 is arranged upstream of the fuel discharge hole 96 in an intake system of the engine E.

[0018] The intake quantity control device 10 will be described with reference to Fig. 1-Fig. 3. The intake quantity control device 10 is provided with a throttle body 11 made of synthetic resin (for example, made of PPS). The throttle body 11 has a intake path 12 with a downstream side thereof is faced slightly downward and slanted, and an upstream end section thereof is enlarging in diameter in a funnel shape, and an annular recess section 13a is formed on an inner peripheral surface of a downstream end section thereof.

[0019] An air cleaner (not illustrated) is connected with the funnel-shaped upstream end section of the intake path 12 via a rubber made intake duct 95. In this case, the intake duct 95 and a case main body of the air cleaner are made of synthetic resin, and when these are integrally molded together with the throttle body 11, simplification of structure can be realized. At that time, compact formation of structure is possible to be realized by arranging the throttle body 11 inside the air cleaner.

[0020] The throttle body 11 is provided with a rectilinear passage 33 being a auxiliary intake path 34, which will be described later, in parallel with the intake path 12 which is opening on the downstream end face of the body 11, and an annular recessed section 13b is also formed on an inner peripheral surface of a downstream end section of the rectilinear passage 33.

[0021] On the other hand, the intake tube 8 is provided with an intake passage 8a for communicating the intake path 12 with the intake port 3 of the engine E and an auxiliary intake passage 8b for communicating the rectilinear passage 33 with a supercharging pump 36 driven by the engine E, and a pair of fitting cylindrical sections 26a and 26b are formed at an upstream end section of the intake tube 8 corresponding to the intake passage 8a and the auxiliary intake passage 8b, and these fitting sections 26a and 26b are fitted in the annular recess sections 13a and 13b described above respectively via seal members 14a and 14b.

[0022] The throttle body 11 and the intake tube 8 include coupling flanges 15 and 16 formed to be brought into contact with each other, these flanges are connected with each other by means of a coupling ring 17 in a shape of U letter in section. Thereby, the throttle body 11 is coupled with the intake tube 8. At that time, the seal members 14a and 14b mounted on respective outer periphery of fitting cylindrical sections 26a and 26b of the intake tube 8 are brought into close contact with inner peripheral surfaces of the annular recessed sections 13a and 13b of the throttle body 11, and since air tightness between interiors of the throttle body 11 and the intake tube 8 is to be held, thus, not only the air tightness between the throttle body 11 and the intake tube 8 can be secured, while finishing machining of respective end faces of both of the coupling flanges 15 and 16 is made unnecessary, but also both flanges wall thickness are capable of thinning, to thereby realize compact formation of the coupling section.

[0023] As illustrated in Fig. 2-Fig. 4, the throttle body 11 is provided with a fitting hole 18 which is larger in diameter than that of the intake path 12 so as to cross at right angle with an axis X of the intake path 12, a rotary type throttle valve 20 is rotatably fitted in the fitting hole 18. The throttle valve 20 is also made of synthetic resin (for example, made of 6/6 nylon). At one end of the throttle valve 20, a flange 21 is formed, and the flange 21 is supported by being nipped between a step section 22 of the throttle body 11 and a snap ring 23 locked to the throttle body 11, to thereby specify axial directional position of the throttle valve 20.

[0024] The throttle body 11 includes an annular groove 24 formed adjacent to the flange 21 described above, a seal member 25 to be brought into close contact with an outer peripheral surface of the throttle valve 20 is installed in the annular groove 24.

[0025] Further, the throttle valve 20 includes a valve hole 27 formed having the same sectional surface with that of the intake path 12 described above, and the valve hole 27 is designed in such a manner that at the position where the throttle valve 20 is entirely closed (refer to Fig. 7 (A)), the throttle valve 20 and the intake path 12 are gone completely crisscross and are brought into non- passing state, whereas at the position where the throttle valve 20 is entirely opened (refer to Fig. 7 (C)), the throttle valve is coincided with the intake path 12 so as to form a continuous intake path 12.

[0026] A driving drum 39 having a wire groove 38 on an outer periphery thereof is integrally molded with the throttle valve 20 at one end thereof, an operation wire 30 engaging with the wire groove 38 is connected at one end thereof with the driving drum 39 and the wire 30 is also connected at the other end thereof with a throttle grip of a steering handle not illustrated. When the operation wire 30 is towed by rotating the throttle grip, throttle valve 20 can be rotated from the entire closing position to entire opening position as described above.

[0027] A vertical hole 31 ranging from the other end face of the valve 20 to the valve hole 27 and a horizontal hole 32 passing through one side wall of the vertical hole 31 are formed in the throttle valve 20, and the rectilinear passage 33 which is communicated with the horizontal hole 32 and opened on an upstream end face of the body 11, is formed in the throttle body 11. The auxiliary intake path 34 is constituted of these vertical hole 31, the horizontal hole 32 and the rectilinear passage 33. The auxiliary intake path 34 is connected with the supercharging pump 36 via the auxiliary intake passage 8b of the intake tube 8 as described above.
[0028]

[0028] A synthetic resin made cap 38, which closes an opening section of the vertical hole 31 described above is welded on the other end face of the throttle valve 20, and a coupling shaft 39 having an oval shape section extending coaxial with the throttle valve 20 is integrally molded with the cap 38. A coupling cylinder 41 for a rotor 40r of a throttle position sensor Sth for detecting an opening degree of the throttle valve 20 is fitted on the coupling shaft 39.

[0029] Meanwhile, in a case where the throttle body 11 is not provided with the auxiliary intake passage 8b, the throttle valve 20 can be integrally molded with the coupling shaft 39.

[0030] The coupling cylinder 41 includes slits 42 formed at the tip end thereof to impart contraction diameter elasticity as illustrated in Fig. 3-Fig. 6, and designed so as to be fittable without play to an outer peripheral surface of the coupling shaft 39. A return spring 37 composed of a twist coil spring for energizing the throttle valve 20 in a closing direction is connected with a space between the rotor 40r and the throttle body 11 via the rotor 40r. Accordingly, the return spring 37 serves as a common return spring for both the throttle valve 20 and the rotor 40r.

[0031] A control unit mounting section 43 in a shape of tray is integrally molded with the throttle body 11, and an electronic control unit U is mounted on the section 43. The electronic control unit U is constituted of a sensor board 44 confronting a bottom surface of the control unit mounting section 43, of an element board 45 arranged to be overlapped with a back surface of the sensor board 44, and of a unit housing 46 containing these boards 44 and 45.

[0032] The sensor board 44 is provided with a supporting hole 49 into which a central shaft 48 for the rotor 40r of the throttle position sensor Sth described above is rotatably fitted and includes a stator 40s formed for converting a rotational angle of the rotor 40r, that is, the opening degree of the throttle valve 20 into an electric signal via a brush 50. Further, a boost negative pressure sensor Spb is mounted on the sensor board 44. The boost negative pressure sensor Spb detects boost negative pressure of the engine E, in other words, engine load is detected through a detecting hole 47 opening to the intake path 12 downstream of the throttle valve 20, and the engine load is designed to be converted into an electric signal.

[0033] Meanwhile, in the throttle position sensor Sth, the brush 50 can be provided on the stator 40s side by transposing an opposing face of the rotor 40r and the stator 40s. Further, the throttle position sensor Sth is possible, of course, to be constituted of non-contact type by utilizing a hole element and a magnet.

[0034] In addition, the sensor board 44 is protrusively provided on an under surface thereof with a male-shaped connecting terminal 51a, and the control unit mounting section 43 is provided on a bottom face thereof with a female-shaped connecting terminal 51b to be connected with the male-shaped terminal 51a. A lead wire 52 which is communicated with an intake air temperature sensor St facing to an inlet of the intake path 12 of the throttle body 11, is connected with the female-shaped connecting terminal 51b. These intake air temperature sensor St, the lead wire 52 and the female- shaped connecting terminal 51b are embedded in the throttle body 11 when the body 11 is molded. With this constitution, wiring work between the intake air temperature sensor St and the electronic control unit U can be obviated. Further, since the electronic control unit U is integrally mounted on the throttle body 11, temperature of intake air flowing along the intake path 12 can be indirectly detected through the throttle body 11, even if the electronic control unit U is annexedly provided with the intake air temperature sensor St, so that omission of wiring of the lead wire to be communicated with the intake air temperature sensor St is made possible.

[0035] A female-shaped connecting terminal 80b to be communicated with the stator 40s of the throttle position sensor Sth, the boost negative pressure sensor Stp and the male-shaped connecting terminal 51a or the like is embedded in the sensor board 44 on an upper surface thereof.

[0036] The element board 45 is annexedly provided with a male-shaped connecting terminal 80a to be connected with the female-shaped connecting terminal 80b described above, with a fuel injection quantity control element 81 to be communicated with the male-shaped connecting terminal 80a, with a fuel injection timing control element 82, with an ignition timing control element 83, with the other various control elements, and other than that with an LED indicator 84 utilized for testing of the electronic control unit U or for a failed alarm, and element board 45 together with these is molded and connected with the unit housing 46. According to this sort of constitution, there becomes to be no need to install the indicator 84 on a special instrument board or the like and wiring for that can also be obviated.

[0037] A coupler housing 85 is integrally formed with the unit housing 85 on one side thereof, in an interior of the coupler housing 85, a plurality of coupler terminals 86 (in a drawing, only one piece out of them is illustrated) to be communicated with respective elements described above are arranged, and a coupler half body 87a is constituted of them. With such a constitution, when the electronic control unit U is integrally provided with the coupler half body 87a, the wiring work between the unit U and the body 87a is to be obviated and a curtailment in the number of part items is capable of being realized.

[0038] The coupler half body 87a is connected with an exterior power supply, an engine revolutionary speed sensor Sne, a crank position sensor Sc and other various sensors, and the other coupler half body 87b having connecting terminals to be communicated with an ignition timing control device Ig and the other various control equipment.

[0039] The fuel injection quantity control element 81 and the fuel injection timing control element 82 described above may well to be operated by connecting the elements 81 and 82 with a solenoid of the electromagnetic fuel injection valve 9 described above via both the coupler half bodies 87a and 87b described above, however, in the case of illustrated embodiment, lead wires 88 and 89 connecting output sections of the fuel injection quantity control element 81 and the fuel injection timing control element 82 with the solenoid of the fuel injection valve 9 are embedded in the throttle body 11 and the intake tube 8. At that time, a female-shaped connecting terminal 90b and a male-shaped connecting terminal 90a connecting between both the lead wires 88 and 89 with each other are respectively provided on a joining face of the throttle body 11 with the intake tube 8, further, a pair of connecting terminal the same as those described above are also provided respectively on a joining face of the intake tube 8 with the fuel injection valve 9. With this contrivance, electrical connection can be conducted simultaneous with assembling of parts, to thereby contribute an improvement in an assembling property and a reduction in the number of part items. Further, when the throttle body 11 and the intake tube 8 are integrally molded out of synthetic resin, connecting terminals are also obviated, and further reduction in the number of part items can be realized.

[0040] Further, in mounting the electronic control unit U on the throttle body 11, the sensor board 44 has been underlaid overlapping the element board 45 on the board 44 in advance and the connecting terminals 80a and 80b has been connected with each other. Then, when the unit housing 46 is fitted in a tongue groove fitting manner on the control unit mounting section 43 of the throttle body 11, the connecting terminals 51a and 51b of the sensor board 44 and the throttle body 11 are connected with each other, and with this state, contact surfaces between the unit housing 46 and the control unit mounting section 43 are welded together. Meanwhile, the unit housing 46 and the control unit mounting section 43 are capable of being separably connected with each other by means of a clip or a screw or the like, with such a structure, maintenance and inspection operations of an interior of the electronic unit U are possible to be carried out.

[0041] In Fig. 3 and Fig. 7, the throttle body 11 is provided with a bypass passage 53 for bypassing the throttle valve 20 and for connecting both ends thereof with the intake path 12, and a first idle device 55 which faces a piston type valve element 54 to the bypass passage 53 is mounted on the throttle body 11.

[0042] The throttle body is provided with a valve guiding hole 56 in which the valve element 54 is slidably fitted, with an inlet chamber 57 opening on an end face of the valve guiding hole 56, and with an outlet chamber 58 communicating with the valve guiding hole 56 on one side surface thereof via a plurality of small holes 59 extending in a slidably moving direction of the valve element 54. The bypass passage 53 is composed of a bypass passage upstream section 53a for connecting it with upstream of the intake path 12 and of a bypass passage downstream section 53b for connecting it with the downstream of the intake path 12, the bypass passage upstream section 53a is connected at a downstream end thereof with the inlet chamber 57 described above, and the bypass passage downstream section 53b is connected at an upstream end thereof with the outlet chamber 58 described above.

[0043] Further, when the valve element 54 moves inside a valve guiding hole 56, an opening degree of a small hole 59 group is adjusted with a side surface of the valve element 54, and an intake quantity flowing along the bypass passage 53 is determined by the opening degree of the small hole 59 group.

[0044] The first idle device 55 is composed of the valve element 54 described above and a temperature sensitive operating means 60 for operating the valve element 54 described above corresponding to a change in temperature of the engine E. The temperature sensitive operating means 60 is composed of a housing 62 fitted and fixed in a mounting hole 61 of the throttle body 11, of a wax holder 63 in a shape of cylinder having a bottom fitted in the housing 62, a wax case 65 fitted and held with the wax holder 63 and sealed wax 64 inside thereof, of an output rod 68 slidably fitted in a bearing 66 located at one end section of the wax case 65, one end of the rod 68 is opposed to the wax 64 via a seal piston 67 and the other end of the rod 68 is projected outside the wax case 65, of an operating member 69, in a shape of a cylinder having a bottom, while an interior end face of the member 69 is brought into contact with a tip end of the rod 68, is slidably fitted on an outer circumference of the wax case 65, of a return spring 70 for energizing the operating member 69 to an operating rod 68 side, and of an electric heater 71 annexedly provided on the wax holder 63, the electric heater 71 is carried a current after starting of the engine E so as to heat the wax 64 corresponding to a rise in temperature of the engine E.

[0045] The operating member 69 is integrally provided on an outer end face thereof with a coupling shaft 74 coaxially arranged side by side with the output rod 68, and the coupling shaft 74 is slidably fitted into a coupling hole 75 having a bottom located on an opposite side of the inlet chamber 57 described above and formed on an end face of the valve element 54. The coupling shaft 74 includes an outward facing flange 74a formed at a tip end thereof and the coupling hole 75 further includes an inward facing flange 75a formed at an opening end thereof respectively, and a sliding limit in a elongating direction of the coupling shaft 74 and the valve element 54 is specified by bringing the flange 74a into contact with the flange 75a. A lost motion spring 76 for energizing the coupling shaft 74 and the valve element 54 in a elongating direction, that is, in a closing direction, by mentioning with regard to the valve element 54, is contractably provided between them 74 and 54.

[0046] Therefore, during a cold weather season, when the wax 64 in the wax case 65 is in a contracted state, the operating member 69 is retreated so as to push the output rod 68 within the wax case 65 by application of load of the return spring 70, or when the wax 64 is expanded by heating of the heater 71, the output rod 68 operates the operating member 69 so as to advance the member 69 on the valve element 54 side against the load of the return spring 70. Accordingly, the valve element 54 increases the opening degree of the small hole 59 group at the time of contraction of the wax 64 and decreases the opening degree of the small hole 59 group according to the expansion of the wax 64.

[0047] Further, throttle body 11 is provided with a movable stopper means 77 to be capable of adjusting a closedown position of the valve element 54 described above. The movable stopper means 77 is constituted of a stopper bolt 78 threadedly engaged with the throttle body 11 so as to oppose to the end face of the valve element 54 by passing through the inlet chamber 57 described above and of an coil spring 79 nipped between a head section of the stopper bolt 78 and the throttle body 11, and prevents a wild movement of the stopper bolt 78.

[0048] Next, operation of the embodiment will be described.

[0049] During the engine E is started and exerts idling driving, the throttle valve 20 sets the valve hole 27 at a full closed position, where the hole 27 and the intake path 12 are made to go completely crisscross each other. Since the throttle valve 20 is a rotary type and a fitting state of the throttle valve 20 into the fitting hole 18 of the throttle body 11 is invariably constant, there is no possibility of adherence even at the full closing position, as is the case in the conventional butterfly type throttle valve. In addition, when the engine E is driven, since the throttle valve 20 is pulled close to the downstream of the intake path 12 and is brought into close contact with one side of the fitting hole 18 due to operation of an intake negative pressure, leakage of air from the fitting hole 18 is inhibited, and an excellent full closing state of the throttle valve 20 is capable of being provided.

[0050] On the other hand, during a cold weather season, in a first idle adjusting device 55, since the wax 64 is in a state of contraction, the operating member 69 occupies the retreat position due to the load of the return spring 70. Under this state, since the coupling shaft 74 of the operating member 69 and the valve element 54 is in such a coupling state as the outward facing flange 74a is mutually brought into contact with the inward facing flange 75a due to the load of the lost motion spring 76, the valve element 54 is held at a high opening degree position where the small hole 59 group is largely opened by means of the operating member 69.

[0051] Then, when the engine E is started under the full closing state of the throttle valve 8, since air is sucked into the engine E through the bypass passage 53 and the intake quantity of air is controlled in a comparatively large amount by means of the small hole 59 group, a comparatively large amount of rich air-fuel mixture suitable to starting can be prepared by mixing sucked air with fuel injected from the fuel injection valve 9, to thereby positively be able to start the engine E. Further, since comparatively a large amount of air-fuel mixture is supplied to the engine E similar as described above even under a warming up state of the engine E, the engine E is provided with first idling revolutionary speed, so that warming up of the engine E can be accelerated.

[0052] When warming up of the engine E is progressed and temperature of the engine E is to be raised, since the heater 71 heats the wax 64 according to the increase of the engine temperature, the wax is expanded and thus the operating member 69 is to be advanced against the load of the return spring 70. In association with this, since the valve element 54 is pushed in a closing direction, the opening degree of the small hole 59 group is to be decreased, thus the intake quantity passing through the bypass passage 53 is decreased, of course, a fuel injection quantity of the fuel injection valve 9 is decreased according to the decrease of an intake quantity, hence lowers first idling revolutionary speed.

[0053] Further, when the valve element 54 reaches a contact position with the stopper bolt 78, that is, the closedown position, the opening degree of the small hole 59 group to be minimized, to thereby minimize the intake quantity. By means of the minimum intake quantity, a normal idling revolutionary speed of the engine E can be secured. Accordingly, the minimum intake quantity can be adjusted by changing the closedown position of the valve element 54, when the stopper bolt 78 is adjusted to advance/retreat relative to the valve element 54, thus, the idling revolutionary speed is possible to be adjusted to a desired value. Further, since an adjustment of the minimum intake quantity is to be conducted with the adjustment of the opening degree of the small hole 59 group provided with the bypass passage 53 having much smaller diameter than the intake path 12, a fine adjustment of the minimum intake quantity can easily be conducted without requiring a special skill. As described above, when the rotary type throttle valve 20 is held in an excellent full closing state, dispersion of a adjustment amount of the first idling device 55 described above and the stopper bolt 78 is eliminated, or is remarkably reduced, the stable first idling and normal idling states of the engine E are possible to be obtained.

[0054] Thereafter, when the wax 64 expands further and the operating member 69 advances further, since the coupling shaft 74 enters deeply into the coupling hole 75 of the valve element 54 while the shaft 74 compresses the lost motion spring 76, generation of excessive stress can be avoided by letting the excessive expansion of the wax 64 to be absorbed to the lost motion spring 76 while the valve element 54 being held in a specified closing position.

[0055] Meanwhile, if the valve element 54 is made to be operated by a linear solenoid in place of the wax 64, the idle control of the engine E can be conducted in a more elaborate manner.

[0056] When the operation wire 30 is towed and the throttle valve 20 is rotated in the valve opening direction in order to increase the output of the engine E, since the valve hole 27 of the throttle valve 20 appears on the intake path 12 and increases the opening degree thereof, the intake quantity of the engine E can be increased. At that time, since the valve opening direction of the throttle valve 20 is designed, as described above, to be a direction where a lower section of the valve 20 is directed downstream of the intake path 12, as illustrated in Fig. 8(B), when the throttle valve is at an intermediate opening degree, the throttle body 11 exposes a lower section of the fitting hole 18 thereof to the intake path 12, even if fuel tries to be trapped to the lower section of the fitting hole 18 caused by a spit-back of intake air, since air flowed in from the inlet of the intake path 12 descends the valve hole 27 obliquely and air flows along a bottom surface of the fitting hole 18 while being accompanied by the fuel described above, fuel can be previously prevented from being trapped at the lower section of the fitting hole 18. Accordingly, influence of air-fuel mixture upon fluctuation of an air-fuel ratio is possible to be avoided. Further, at this time, the bottom surface of the valve hole 27 of the throttle valve 20 certainly prevents fuel from transferring downstream, by means of an attitude of an upgrade directed to the downstream of the intake path 12.

[0057] As illustrated in Fig. 8 (C), when the throttle valve 20 is rotated to the full opening position, the valve hole 27 is coincided with the intake path 12, since the intake path 12 includes a continuous intake path 12 formed without being existed nothing therein, an intake resistance of the intake path 12 is remarkably reduced and an improvement in high output performance of the engine E is possible to be realized.

[0058] Further, since the fuel discharge hole 96 is arranged more on the downstream side of the throttle body 11 and injected fuel from the fuel injection valve 9 is discharged to the intake port 3, a fuel supply system is not to become intake resistance and such an arrangement is especially advantageous at full closing time described above of the throttle valve 20, further, since fuel does not pass through inside the throttle valve 11, the fluctuation of the air-fuel ratio can be prevented from occurring by restraining adherence of fuel with a valve wall to the minimum.

[0059] During that time, air discharged from the supercharging pump 36 is supplied to the engine E through the auxiliary intake path 34 and contributes to a further improvement in output by enhancing charging efficiency of the engine E. By the way, since the auxiliary intake path 34 described above is provided ranging over the throttle body 11 and throttle valve 20 so as to open the intake path 34 to the valve hole 27, formation of the auxiliary intake path 34 within the throttle body 11 is sufficient to be lessened. That is, the rectilinear passage 33 only is to be formed, thus, molding of the throttle body 11 having the auxiliary intake path 34 is capable of being easily conducted.

[0060] Next, when tractive force applied to the operation wire 30 is released in order to decrease the output of the engine E, the throttle valve 20 returns to the full closing position by repulsive force of the return spring 37, the engine E again becomes in the idling state.

[0061] Further, since the throttle body 11 along with the throttle valve 20 are made of synthetic resin, a friction factor of rotary fitting surfaces between both of them is comparatively low and surface hardness for each of them is also comparatively low, a rotary surface of the throttle body 11 is easy to get intimate with that of the throttle valve 20 in the early stage, accordingly, opening/closing of the throttle valve 20 can nimbly be performed, a leakage amount of air from the rotary face is possible to be stabilized in the early stage.

[0062] Moreover, since the throttle valve 20 is of a rotary type, a contact surface of the throttle body 11 with that of the throttle valve 20 is possible to be formed remarkably large with each other and thus excellent thermal radiation and reception properties can be obtained, further, since mutual contact areas are large, a closing property of the throttle valve 20 at the full closing position is to be excellent, thus, such a structure can contribute to stabilization of the idling of the engine E.

[0063] Fig. 9 shows a diagrammatic view of characteristic illustrating relationship between the throttle valve opening degree and the intake quantity in the intake quantity control device 10 of the present invention and also shows that the characteristic of the control device 10 is variable by selecting sectional shapes of the intake path 12 and the valve hole 27 in a wide range such as a circle, a corner rounded triangle and an invert-located corner rounded triangle.

[0064] During an operation of the engine E having the structure described above, in the throttle position sensor Sth in which the rotor 40r is directly coupled with the throttle valve 20, the opening degree of the throttle valve 20 can accurately be detected. Further, the fuel injection quantity control element 81, the fuel injection timing control element 82 and ignition timing control element 83 in the electronic control unit 46 receive electric signals outputted from the throttle position sensor Sth, the boost negative pressure sensor Spb, the intake air temperature sensor St, the engine revolutionary speed sensor Sne and the crank position sensor Sc and the like, and discriminate an engine driving state at that time, the fuel injection quantity control element 81 and fuel injection timing control element 82 determine the fuel injection quantity and injection timing of the fuel injection valve 9 and operate the valve 9 in such a manner, the ignition timing control element 83 determines ignition timing and operates an ignition device not illustrated following the determination.

[0065] By the way, since the sensor board 44 provided with the throttle position sensor Sth and the boost negative pressure sensor Spb and the element board 45 provided with the fuel injection quantity control element 81, the fuel injection timing control element 82 and the ignition timing control element 83 constitute the electronic control unit U by being contained in a single unit housing 46 and are mounted on the control unit mounting section 43 of the throttle body 11, various sensors Sth and Spb and various control elements 81-83 are unitized and the unitized substance can be installed in a compact manner. Accordingly, an installation space for the electronic control unit except the throttle body 11 is to become needless to be prepared, thus space efficiency is improved, the compact formation of the control system therefore the compact formation of the intake system can be realized. Further, not only the simplification of the wiring between the throttle position sensor Sth and the various control elements 81-83, but also a wiring integration of signal wires from an electric supply cord and the engine revolutionary speed sensor Sne necessary for an operation of various control elements 81-83 are possible to be realized. With this constitution, the simplification of the wiring is advantageous in order to lessen the influence of a magnetic wave or the like.

[0066] In addition, in the throttle position sensor Sth, since the rotor 40r is directly coupled with the throttle valve 20, the opening degree of the throttle valve 20 can accurately be detected.

[0067] Further, since the various control elements 81-83 are arranged on a large back face of the sensor board 44 via the element board 45, the various control elements 81-83 are possible to be freely arranged without being interfered with the throttle position sensor Sth and the boost negative pressure sensor Spb, degrees of freedom for a layout of the equipment are large.

[0068] Further, especially, since the sensor board 44 and the element board 45 are to be separably connected in a laminated state with each other and the electronic control unit U of various characteristics is capable of being inexpensively provided by varying a specification for various sensors and elements to be mounted on the sensor board 44 and the element board 45 according to sorts of machines, in addition to the unit U being of compact size.

[0069] Moreover, since the throttle body 11 is made of synthetic resin, the body 11 itself has an insulating property, accordingly, the electronic control unit U can be mounted on the body 11 without interposing thereto a special insulating member, therefore the simplification of a mounting structure can be realized.

[0070] A second embodiment of the present invention as illustrated in Fig. 10 is similar constitution as the previous embodiment except a point that the valve hole 27 of the rotary type throttle valve 20 is formed one side thereof in a notched shape which is opened upward at the time of full opening, and in a drawing, parts corresponding to the previous embodiment are denoted by the same reference numerals, thus the description thereabout is omitted.

[0071] A third embodiment of the present invention as illustrated in Fig. 11 is similar constitution as the previous embodiment except following points that the rotary type throttle valve 20 is arranged having a lower face thereof being coincided with a bottom face of the intake path 12 in the throttle body 11 and that the valve hole 27 of the throttle valve 20 is formed one side thereof in a notched shape which is opened to the lower side at the time of full opening, and in a drawing, parts corresponding to the previous embodiment are denoted by the same reference numerals, thus the descriptions thereabout are omitted. According to the third embodiment, the intake path 12 does not form a recessed section for the fitting hole 18 in which the throttle valve 20 is fitted on the bottom face of the path 12, hence prevents fuel from being trapped therein.

[0072] The present invention is not limited to the respective embodiment described above, and various changes in design can be conducted in a scope without departing from the present inventive concept.

Effect of the Invention

[0073] According to a first aspect of the present invention as described above, in an engine intake system provided with a throttle body having an intake path to be communicated with an intake port of an engine, a throttle valve for controlling an intake quantity of the engine by the intake path and a fuel injection valve for injecting fuel to be supplied to the engine, since the throttle body is mounted with an electronic control unit integrated with a throttle position sensor for detecting an opening degree of the throttle valve and fuel injection control elements for controlling fuel injection quantity of the fuel injection valve on the basis of an output signal of at least the throttle position sensor, the throttle position sensor and the fuel injection control elements are unitized and are capable of being mounted on the throttle body in a compact manner, it becomes unnecessary to prepare an installation space for the electronic control unit except for the throttle body, thus the present invention can greatly contribute to compact formation of the intake system, besides, simplification of wiring between the throttle position sensor and the fuel injection control elements can be realized.

[0074] Further, according to a second aspect of the present invention, the throttle position sensor is constituted of a rotor rotating in cooperation with an opening degree of the throttle valve and a stator to be opposed to the rotor for converting a rotating angle of the rotor into an electric signal, and since the stator is provided on a sensor board of the electronic control unit and the fuel injection control elements are arranged on a back face side of a sensor board on an opposite side of the throttle position sensor, it enables the fuel injection control elements to be freely arranged on a large back face side of the sensor board, a layout design of them can easily be carried out.

[0075] Further, according to a third aspect of the present invention, since the throttle body is made of synthetic resin, the electronic control unit can be mounted on the throttle body without interposing a special insulating member and simplification of a mounting structure of the unit is possible to be realized.

[0076] Furthermore, according to a fourth aspect of the present invention, since the electronic control unit is integrated with further the ignition timing control element for controlling ignition timing of the engine, not only the throttle position sensor and the fuel injection control elements but also an ignition control element are able to be unitized and can be mounted on the throttle body in a compact manner, thus simplification of an engine control system is possible to be realized.

Claims

1. An intake system of an engine characterized in that the engine intake system includes a throttle body (11) having an intake path (12) communicating with an intake port (3) of an engine (E), a throttle valve (20) for controlling an intake quantity of the engine by means of the intake path (12), and a fuel injection valve (9) for injecting fuel to be supplied to the engine (E), said throttle body (11) mounted with an electronic control unit (U) integrated with a throttle position sensor (Sth) for detecting an opening degree of said throttle valve (20) and fuel injection control elements (81) and (82) for controlling a fuel injection quantity of said fuel injection valve (9) at least on the basis of an output signal of the throttle position sensor (Sth).

2. An intake system of an engine as set forth in claim 1, characterized in that said throttle position sensor (Sth) comprises a rotor (40r) rotating in cooperation with the opening degree of said throttle valve (20) and a stator (40s) opposed to the rotor (40r) for converting a rotating angle of the rotor (40r) into an electric signal, the stator (40s) is provided on a sensor board (44) of the electronic control unit (U), and said fuel injection control elements (81) and (82) are arranged on a back face side of the sensor board (44) on a side thereof opposed to the throttle position sensor (Sth).

3. An intake system of an engine as set forth in claim 1 or claim 2, characterized in that said throttle body (11) is made of a synthetic resin.

4. An intake system of an engine as set forth in any one of claim 1 through claim 3, characterized in that said electronic control unit (U) is further integrated with an ignition timing control element (83) for controlling ignition timing of the engine (E).

Drawing