Bevel gear

Abstract

 A bevel gear with input and output shafts (20 and 30) where a first bevel pinion (37) on the input shaft is at right-angles to, and in mesh with a bevel gear wheel (39), which via a claw coupling (44) and a friction clutch (45) is in power transmitting communicatin with the output shaft. Distinguishing for the invention is a bearing block (34) of generally quadratic configuration and in two adjacent side surfaces rotatably carrying the pinion and gear wheel, the input shaft being disposed in a through bore (35) in the bearing block, the bore being accessible from two diametrically oppsoed sides of the bearing housing (27) via openings (32, 33) in the wall of the bearing housing, whereby, after installing the bearing housing so that the input shaft forms a desired angle to a vertical plane, a sun shield is reeled out when the input shaft is turned clockwise, independent of whether the gear is fitted to the let or to the right of the longitudinal shaft (2) on which the sun shield is carried.

Description

[0001] The present invention relates to a bevel gear of the kind disclosed in the preamble of the accompanying claim 1. A gear of this kind is known and is used in operating sun .shields such as venetian blinds, awnings, revolving shutters etc., with the aid of a shaft which is provided with a crank. In operating the sun shield, e.g. when angling the slats of a venetian blind and raising it, or when pulling out and retracting an awning, the end of the shaft provided with said crank is inserted into a hollow input shaft of the bevel gear and the crank is turned. When the crank is turned clockwise it is desired that the sun shield shall expose the window, but when the crank is turned counter clockwise the shield shall cover the window, at the upper edge of which the shield is mounted. For different reasons, the bevel gear must sometimes be arranged at the left hand end and sometimes at the right hand end of a longitudinal operating shaft by which the shield is operated. This creates a problem with the known bevel gear, since two different models must be marketed, one for mounting to the let and the other for mounting to the right of the longitudinal operating shaft.

[0002] Another problem with the known bevel gear is that for its assembly with the sun shield a separate holder is required for fixing the bevel gear at a desired angular attitude of its hollow input shaft relative a vertical plane. The holder is fitted into a base member, which is arranged in the upper area of the window and, inter alia, accommodates the mentioned longitudinal operating shaft. The same holder means can be used irrespective of whether the bevel gear is intended for right- or left-hand fitting, but merely the fact that a separate holder means must be fitted into the base member is a disadvantage, partly since separate holder means must then be kept in stock and partly in that fitting the bevel gear in the base member is complicated and time- consuming.

[0003] The present invention attempts to mitigate the above- mentioned problems with the known bevel gear and has the object of achieving a bevel gear which can be used for both right- and left-hand fitting. The feature enabling the same gear to be used for both purposes are apparent from the characterizing portion of the appended claim 1. The features enabling the omission of a separate holder means for setting the angular attitude of the input shaft relative a vertical plane are apparent from the particular embodiment described in claim 6.

[0004] The invention will now be described in detail, in connection with the accompanying drawings, on which

Figure 1 is an exploded perspective view of a known bevel gear for right-hand fitting in a sun shield, which is here in the form of a venetian blind,

Figure 2 illustrates the known gear in cross section,

Figure 3 is a perspective view of the gear in accordance with the present invention,

Figure 4 is a cross section of the gear according to the invention,

Figure 5 is a partially exploded perspective view of the main details forming a coupling associated with the gear and the friction clutch coacting with the coupling,

Figure 6 is a perspective view of the assembled coupling unit before fitting it to a bearing block in the bevel gear according to the invention,

Figure 7 illustrates the coupling unit and bearing block combined into a unit before mountig in a housing half, and

Figure B illustrates the inventive gear fitted into two mutually turnable housing halves.

[0005] Figure 1 illustrates a known bevel gear 1, intended to be mounted on a longitudinal operating shaft 2 in a base member 3 with the aid of a holder 4 for the gear. With the aid of a shaft associated with a crank means 5, the sun shield, a venetian blind in this embodiment of the invention, may be raised and lowered with the aid of a lifting cord 6, and angled with the aid of a ladder cord 7. The setting movements of the blind are achieved by turning the longitudinal shaft 2, whereby means, not shown but accommodated in the base member and driven by the shaft then coacts with the lifting and ladder cords.

[0006] As mentioned in the introductory portion, the venetian blind is conventionally raised when the crank means 5 is rotated clockwise. If, for example, the space round the base member does not allow the gear to be placed to the right as in Fig. 1, it may have to be placed to the left in the member. For such left-hand fitting the blind must still go up when the crank means is turned clockwise. To achieve this, the known bevel gear illustrated in Fig. 2 is provided with a housing 8 having two chambers 9 and 10. A bevel gear wheel 11 driven by a bevel pinion 12, which is non-rotatably disposed on the input shaft 13 of the gear, can be placed in either one of the two chambers 9 and 10, depending on whether the gear is to be fitted to the left or to the right. If the wheel 11 is placed in the chamber 9, the bevel gear is suitable for fitting to the left. If the gear is to be used for right-hand fitting, the wheel 11 must be arranged in the chamber 10 so that the output shaft 14 of the gear will rotate in a direction causing the blind to be raised when the crank means is rotated clockwise. The wheel 11 is non-rotatably disposed, e.g. with the aid of splines, on a hollow shaft 15 which, with the aid of a claw coupling generally denoted by 16, is in power transmission communication with the output shaft 14 via a friction clutch 17. The hollow output shaft 14 extends between the two end walls 18 and 19 of the bevel gear housing 8.

[0007] The bevel gear is mounted on the longitudinal shaft 2 and thrust into the holder 4 which is then put into the base member 3. The housing 8 is subsequently turned until the input shaft forms the desired angular attitude relative the vertical plane, after which the position of the housing in the holder 4 is fixed by tightening a set screw 20 on the holder 4 (see Figure 1). The angular attitude mentioned varies from installation, and is, inter alia, dependent on whether the sun shield is to be operated from the outside or inside of the window.

[0008] Figure 3 illustrates a bevel gear 25 in accordance with the present invention. The gear includes two cylindrically shaped housings 26, 27, which are mutually in register axially and are rotatable relative each other. The housing 27 is provided with holder means 28 for fitting the gear into the base member 3 without an intermediate holder. The gear has an input shaft 29 and an output shaft 30. The input shaft is in the housing 26, the angular attitude of which, relative the housing 27, can be locked with the aid of a set screw 31. Fitting the gear is thus considerably facilitated. The output shaft thus only needs to be mounted on the longitudinal operating shaft 2, and the housing 27 inserted into the base member, after which the housing 26 is turned until the input shaft 29 forms the desired angle to the vertical plane. The desired position is then fixed with the aid of the stop screw 31.

[0009] Figure 4 illustrates the bevel gear 25 in cross section. The gist of the invention is that the input shaft 29 is accessible to the shaft of the crank means 5 from two diametrically opposed sides of the input shaft, in contradistinction to the known gear, where the input shaft is only accessible from the side on which the bevel pinion 12 is mounted. Since the inut shaft 29 is accessible from said two diametrically opposed sides, the output shaft 30 can be caused to rotate in the desired direction independent of whether the bevel gear 25 is fitted to the left or to the right. The housing 26 is positioned so that the tip of the shaft portion of the crank means is inserted either through an opening 32 in the wall of the housing 26 or through the diametrically opposing opening 33. To achieve this feature, the gear according to the invention is provided with a bearing block 34 in the form of a solid, substantially rectangular resin block. The bearing block 34 has a first through bore 35, in one end of which the input shaft 29 is rotatably mounted, and in the other end of which a resin tube 36 is disposed. A bevel pinion 37 is non-rotatably mounted on the input shaft 29. The input shaft 29 and the pinion 37 are preferably cast integrally and in metal. From one side wall the bearing block 34 has a projecting annular collar 38 on which is mounted a bevel gear wheel 39. The bevel gear wheel is in a plane normal to that of the pinion 37, with which it is in mesh. The bevel gear wheel 39 has a projecting annular collar 40, the internal surface 41 of which forms a journalling surface for one end portion of the output shaft 30. The external cylindrical surface 42 of the collar 40 is rotatably mounted in an annular flange portion 43 projecting axially of the housing 26. The diameter of the flange 43 is less than the diameter of the rest of the housing 26.

[0010] The bevel gear wheel 39 is connected to the output shaft 30 via a claw coupling 44 and a friction clutch 45 which completely corrspond to the known coupling 16 and friction clutch 17.

[0011] The output shaft 30 has a first portion 46 with a first diameter, a second portion 47 with a second diameter and a third portion 48 with a third diameter. The first portion 46 is rotatably mounted in a tube 49, constituting a portion of the friction clutch. The tube 49 is non-rotably supported in forward front wall 50 of the housing 27. To this end the front wall 50 has a central circular opening 51 with two diametrically opposing projections 52, 53 whch have the form of circular pins directed radially inwardly in the opening. Said projections fit in two corresponding holes in the tube 49, these holes being thus diametrically opposite each other at the end of the tube. The second end portion 47 of the output shaft is rotatably mounted on the internal surface 41 of the collar 40, and the third portion 48 is rotatably mounted on an internal surface 52' of a recess in the end surface of the projecting annular collar 38 of the bearing block 34.

[0012] The bearing block 34 has a second through bore 53, axially in line with the longitudinal axis of the output shaft 30, this axis being in the same plane as the first through bore 35 and forming a right angle to the first bore. The bevel gear thus has an axially central through opening, through which a longitudinal operating shaft 2 can be inserted and locked in position by a set screw 54. At its side surface facing away from the collar 38 the bearing block 34 has a projecting annular boss 55, accommodated in an opening 56 in the wall of the housing 26. The opening 56 is concentric with the shaft 30. The tube 36 in the first through bore 35 of the bearing block is at its top end portion provided with a flange 57, which is in contact with the inside wall of the housing 26. A small portion of the tube 36 projects into the opening 33. The bearing block 34 finally has two lugs 58, 59 which is most clearly apparent form Figures 7 and 8, these lugs resting in two complementary formed depressions 60, 61 (see Fig. 7) in the wall surface of the bearing housing 26, which is divided into two halves 62, 63. The upper housing half 62 has corresponding depressions, not shown, in its wall, whereby screws, not shown, going through the openings in the lugs 58, 59 keep the housing halves 62, 63 and the bearing block 34 together.

[0013] The housing 27 is also divided into two housing halves 64, 65, which are substantially symmetrical, and have a radially inwardly directed flange 66 at their ends facing away from the front wall 50, this flange fitting into a groove 67 made in the collar 43. The housings 26 och 27 are thus rotatable relative each other, and rotating the housing 27 relative the housing 26 results in mutual relative movement of the bevel pinion and the bevel gear wheel.

[0014] Figures 5-8 are now referred to for creating a clear picture of how the bevel gear and the coupling included with it are built up. From Figure 5 it is apparent that the gear wheel 39 has a follower 70 projecting from its collar 40 in the form of a tongue, which constitutes an extended portion of the collar 40. The detail in the middle of Fig. 5 is the output shaft 30 with its first, second and third portions. Between the first and second portions there is a fourth portion 71, forming the bottom of, and integral with, a cylindrical shell 72 with a cut-away portion. Finally, the coupling coacts with the mentioned tube 49 and a helical spring 73 tightly wound onto the tube, the tube and spring forming a clutch. The two ends of the spring are bent out radially to project a distance above the cylindrical body of the spring as illustrated by the reference numeral 74 in Fig. 4. In relation to the circumference of the tube 49, the two bend-out spring ends are at an angular distance from each other which is greater than the angular distance the tongue 70 takes up when the shaft is mounted in the bevel gear wheel 39 in the manner illustrated in Fig. 6. At the same time, the mentioned angular distance between the spring ends is less than the angular distance the cut-away portion of the shell 72 takes up.

[0015] The claw coupling and clutch function such that when the gear wheel 39 is turned, the tongue will come into engagement against one or other spring end and will urge the spring in a direction tending to loosen the turns thereof round the tube, the spring then relinquishing its tight engagement round the tube and turning until the corresponding projecting spring end comes into engagement against one or other edge of the cut-away portion of the shell 72 for transmitting the rotational movement to the output shaft. On the other hand, if the output shaft tends to turn relative the bevel gear, which occurs partly as a result of the own weight of the sun shield or as a result of wind action on the shield, the shell, which is non-rotably disposed on the cylindrical shaft, will come into engagement with one or the other spring end and urge it in a direction tending to clamp the spring so hard round the tube 49 that the spring can not move relative the tube, resulting in that one or other projecting spring end cannot move the tongue.

[0016] After the main details illustrated in Fig. 5 have been assembled to form the right-hand unit illustrated in Fig. 6, the bevel gear wheel is placed on the collar 38 serving as a bearing on the bearing block 34. Although not previously described, the gear wheel 39 has a journalling surface 75 for this purpose (cf. Fig. 4). The unit thus formed is shown to the right in Fig. 7, and this unit is then placed in the lower housing half 63, after the input shaft 29 and its bevel pinion 37 have been placed in the opening 32 in the housing half 63. The lugs 58, 59 on the bearing block are fitted into the depressions 60 and 61 at the same time as the pinion and the gear wheel will mesh with each other, the collar 40 being rotatably carried by its external surface serving as a journalling surface. The lower housing half 65 of the housing 27 is then put in place, forming the unit illustrated in Fig. 8, which illustrates the bevel gear of Fig. 4 seen from above.

[0017] Although the housings 26 and 27 are rotatably arranged relative each other, this is not a essenital feature of the invention, since the technical problem of avoiding two different embodiments of the bevel gear, depending on whether it is to be fitted to the left or to the right of a sunshield, is solved by the arrangement of a through bore 36. Thus, in an alternative embodiment of the invention, the bevel gear can be made with a single split housing similar to the one in Fig. 1 which is mounted in a holder 4. Thereafter the desired angular attitude of the input shaft is put into proper relation with the vertical plane and the housing fixed in the holder 4 with the aid of a set of screw 31.

Claims

1. A bevel gear for use in operating a sun shield of the kind which has a longitudinal shaft (2) at one end of which said bevel gear is adapted to be provided including an input shaft (29), a bevel pinion (37) non-rotatably mounted at the inut shaft, a bevel gear wheel (39) in mesh with the pinion and arranged in a plane at right-angles to that of the pinion, an output shaft (30) to which the longitudinal shaft is intended to be non-rotably mounted, a coupling (44) arranged between the gear wheel and the output shaft, and a housing (26, 27) surrounding the output shaft, which at its one end is rotatably mounted in a front wall of the housing, characterized by a bearing block (34) arranged within the housing (26, 27) and having a first through bore (35) in which the input shaft is rotatably mounted, an annular collar (38) projecting from a side surface of the block and on which the bevel gear wheel is rotatably mounted, a collar (40) projecting from the gear wheel, the output shaft at its opposite end portion being rotably mounted in the internal surface (41) of said gear wheel collar, and two openings (32, 33) arranged diametrically opposite each other in the wall of the housing (26, 27) in alignment with said first through bore (35) through the bearing block.

2. A bevel gear as claimed in claim 1, characterized in that the bearing block has a second thrugh bore (53) extending concentric with the cylindrical collar (38) and passing through the first through bore at right angles to it with the axes of the bores in the same plane.

3. A bevel gear as claimed in claim 2, characterized in that the output shaft (30) has a length which is shorter than that of the housing and that the output shaft, starting from its rotatable mounting in the housing front wall, has in consecutive order, a first portion (46) with a first diameter, rotatably mounted at the front wall (50); a second portion (47) with a second diameter, mounted inside the projecting collar (40) of the second gear wheel; and a third portion (48) with a third diameter, supported by an internal surface (52') of a counter bore provided in the end surface of the collar (38); the second diameter being greater than the first, and the first greater than the third.

4. A bevel gear as claimed in claim 3, characterized by a tube (36), one end of which is arranged in an expanded portion of the end of the first through bore (35) facing away from the end in which the input shaft is mounted in the bearing block, the other end of said tube having a flange (58) adapted to engage the inside of the housing wall, and a portion entending from the flange and fitting into one (33) of said two diametrically opposing openings in the housing.

5. A bevel gear as claimed in claim 4, characterized in that the housing is divided into two axially aligned housings (26, 27) which are rotatable relative each other.

6. A bevel gear as claimed in claim 5, characterized in that each housing consits of two complemental housing halves (62, 63 and 64, 65) fixed to each other that the complemental housing halves (62, 63) of one housing (26) have at one end an axially projecting collar (43) of reduced diameter as well as a radial flange portion to form a peripheral groove (67), that the complementary housing halves (64, 65) of the second housing (27) have at one end surface a radially inwardly directed flange (66) intended for being glidably accommodated in the peripheral groove (67) of the first housing.

7. A bevel gear as claimed in claim 6, characterized in that the bearing block (34) on two opposing side walls thereof is provided with lugs (581 59) for locating the block between the complemental housing halves (62, 63) which form said one housing, said lugs being recieved in depressions (60, 61) provided in the walls of the housing halves.

8. Gear as claimed in claim 7, characterized in that the internal surface of the axially projecting collar (43) on the two complemental housing halves of the housing (26) form a jorunalling surface on which the exterior surface (42) of the collar (40) projecting from the gear wheel is rotatably carried.

9. Gear as claimed in claim 8, characterized in that the complemental housing halves of the second housing (27) have on their outside holder means (28) for fitting the gear in a base member accommodating the operating elements of the sun shield and said longitudinal shaft.

Drawing