CA1212559A - V-shaped pulley clutch for racing vehicles - Google Patents
V-shaped pulley clutch for racing vehiclesInfo
- Publication number
- CA1212559A CA1212559A CA000462301A CA462301A CA1212559A CA 1212559 A CA1212559 A CA 1212559A CA 000462301 A CA000462301 A CA 000462301A CA 462301 A CA462301 A CA 462301A CA 1212559 A CA1212559 A CA 1212559A
- Authority
- CA
- Canada
- Prior art keywords
- drive shaft
- clutch
- cheek
- pulley
- sleeve
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
- F16H61/66—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing specially adapted for continuously variable gearings
- F16H61/662—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing specially adapted for continuously variable gearings with endless flexible members
- F16H61/66231—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing specially adapted for continuously variable gearings with endless flexible members controlling shifting exclusively as a function of speed
- F16H61/66245—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing specially adapted for continuously variable gearings with endless flexible members controlling shifting exclusively as a function of speed using purely mechanical sensing or control means
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H55/00—Elements with teeth or friction surfaces for conveying motion; Worms, pulleys or sheaves for gearing mechanisms
- F16H55/32—Friction members
- F16H55/52—Pulleys or friction discs of adjustable construction
- F16H55/56—Pulleys or friction discs of adjustable construction of which the bearing parts are relatively axially adjustable
- F16H55/563—Pulleys or friction discs of adjustable construction of which the bearing parts are relatively axially adjustable actuated by centrifugal masses
Abstract
ABSTRACT OF THE DISCLOSURE:
V-shaped pulley clutch, for a racing vehicle, including a drive shaft, a pulley cheek mounted on this drive shaft for slidable movement along the shaft for engagement of the clutch, a cam ramp secured to the drive shaft in spaced relationship with the slidable pulley cheek and a centrifugal weight assembly including at least two centrifugal weights movable radially out-wardly between the cam ramp and the pulley cheek to push the cheek away from the ramp. The drive shaft is formed with a circumferential groove and the V-shaped pulley clutch further comprises a sleeve solid with the movable pulley cheek and extending over the drive shaft and a plurality of detent mechanisms on the sleeve including detent members radially pressed into the grooves with a force suitable to hold the sleeve and pulley cheek stationary with respect to the drive shaft until the latter rotates at a speed exceeding a predetermined speed capable of releasing the pulley cheek to allow its slidable movement and sudden start of the vehicle.
V-shaped pulley clutch, for a racing vehicle, including a drive shaft, a pulley cheek mounted on this drive shaft for slidable movement along the shaft for engagement of the clutch, a cam ramp secured to the drive shaft in spaced relationship with the slidable pulley cheek and a centrifugal weight assembly including at least two centrifugal weights movable radially out-wardly between the cam ramp and the pulley cheek to push the cheek away from the ramp. The drive shaft is formed with a circumferential groove and the V-shaped pulley clutch further comprises a sleeve solid with the movable pulley cheek and extending over the drive shaft and a plurality of detent mechanisms on the sleeve including detent members radially pressed into the grooves with a force suitable to hold the sleeve and pulley cheek stationary with respect to the drive shaft until the latter rotates at a speed exceeding a predetermined speed capable of releasing the pulley cheek to allow its slidable movement and sudden start of the vehicle.
Description
The present invention relates to a variable diameter V-shaped pulley clutch for particular use in racing vehicle, such as racing snowmobiles, ~otor scooters or similar light weight vehicles, where sudden start of the vehicle is required when the latter stands at the starting line.
The V-shaped pulley clutch oF the invention is used in power transmissions interconnecting a drive shaft and a driven shaft, each shaft having a pulley including a pair of opposed separable radial cheeks defining therebetween a V-groove receiving a likewise V-shaped belt which connects the two pulleys. At idling speed of the engine, the belt lies freely at the bottom of the groove of the drive shaft pulley while it lies at the top of the groove of the driven shaft pulley.
One cheek on each pulley is mounted to move toward the other cheek against the force of a bias. The movable cheek on the drive shaft is further part of and is acted upon by a centrifugal mechanism and responds to centrifugal weights that move radially outward under the centrifugal force that they develop as the drive shaft gradually picks up speed. By this response, the movable cheek is displaced toward the other cheek so that the V-groove of the drive shaft pulley closes in, forcing the belt outwardly while the belt in the driven shaft pulley is simultaneously driven in. In this manner, the low speed high torque originally applied by the driven shaft is gradually changed into a high speed low torque for cruising condition of the vehicle. A
V-shaped pulley clutch of this general type is disclosed in U.S. patent ~o. 3,659,470 of May 2nd 1972.
Where such a vehicle is used in a race, however, and stands at a starting line, it is of course of extreme interest that it accelerates as rapidly as possible to reach its full speed as soon as possible ~2~55~1 after the start signal is given. It is thus an object of the present invention to provide an improved V-shaped pulley clutch that will engage to couple the engine drive shaft to the driven shaft only when the former has reached a predetermined speed of rotation;
a further object being that this predetermined speed be adjustable at will. In this manner, as the racer stands at the starting line, he may rotate the driving shaft at a predetermined maximum idling rotation speed so that, as soon as the start signal is given, he may just slightly increase the rotation speed to cause sudden engagement of the clutch of the driving shaft so that the vehicle may lunge forward.
A search of the prior art relevant to this type of improved V-shaped pulley clutch has been made and has revealed the following U.S. patents: Nos.
The V-shaped pulley clutch oF the invention is used in power transmissions interconnecting a drive shaft and a driven shaft, each shaft having a pulley including a pair of opposed separable radial cheeks defining therebetween a V-groove receiving a likewise V-shaped belt which connects the two pulleys. At idling speed of the engine, the belt lies freely at the bottom of the groove of the drive shaft pulley while it lies at the top of the groove of the driven shaft pulley.
One cheek on each pulley is mounted to move toward the other cheek against the force of a bias. The movable cheek on the drive shaft is further part of and is acted upon by a centrifugal mechanism and responds to centrifugal weights that move radially outward under the centrifugal force that they develop as the drive shaft gradually picks up speed. By this response, the movable cheek is displaced toward the other cheek so that the V-groove of the drive shaft pulley closes in, forcing the belt outwardly while the belt in the driven shaft pulley is simultaneously driven in. In this manner, the low speed high torque originally applied by the driven shaft is gradually changed into a high speed low torque for cruising condition of the vehicle. A
V-shaped pulley clutch of this general type is disclosed in U.S. patent ~o. 3,659,470 of May 2nd 1972.
Where such a vehicle is used in a race, however, and stands at a starting line, it is of course of extreme interest that it accelerates as rapidly as possible to reach its full speed as soon as possible ~2~55~1 after the start signal is given. It is thus an object of the present invention to provide an improved V-shaped pulley clutch that will engage to couple the engine drive shaft to the driven shaft only when the former has reached a predetermined speed of rotation;
a further object being that this predetermined speed be adjustable at will. In this manner, as the racer stands at the starting line, he may rotate the driving shaft at a predetermined maximum idling rotation speed so that, as soon as the start signal is given, he may just slightly increase the rotation speed to cause sudden engagement of the clutch of the driving shaft so that the vehicle may lunge forward.
A search of the prior art relevant to this type of improved V-shaped pulley clutch has been made and has revealed the following U.S. patents: Nos.
2,709,372 of May 31st 1955; 3,685,366 of August 22nd 1972; 4,028,953 of June 14, 1977 and 4,304,150 of ; December 8, 1981. of these, only U.S. patents Nos.
2,709,372 and 3,~85,366 are of interest here and will be analyzed hereinafter.
U.S. patent n 2,709,372 discloses a V-belt sheave mounted on a drive shaft through an outer sleeve freely rotatable on an inner sleeve secured over the drive shaft, the outer sleeve being axially displaceable with respect to the drive shaft. The sheave has one cheek fixed to the sleeve while the other cheek moves with respect to the sleeve so as to be movable toward and away from the fixed cheek. This movement is applied by means of a known centrifugal weight clutching device.
The outer sleeve has, at one end, a clutch plate with axial dogs engageable in dog recesses of a further clutch plate secured to the drive shaft and the inner sleeve.
Energizing of the V--belt of the sheave, between the cheeks, is obtained by manually sliding the slideable 55~
sleeve and cheeks mounted thereon bodiLy until the axial dogs engage in the receiving dog recesses. This manual bodily displacement of the outer sleeve and sheave is con-trolled by means of a lock spring ball detent of the fixed cheek making it possible for the ball of the detent to move into one of two peripheral grooves of the drive shaft inner sleeve. This construction and arrangement which works independently of the rotational speed of the drive shaft, is intended to prevent chafting of the belt in idling position and is no way intended, nor does the disclosure make any suggestion to that effect/ to pxovide for sudden coupling of the sheave cheeks and belt together to give a likewise sudden start to the vehicle being driven through the belt.
U.S. patent n~ 3,685,366 relates to a racing centrifuyal clutch assembly which is provided for inhibit-ing the radial movement of its centrifugal weights that are used to move the displaceable cheek toward the other cheek until the drive shaft has reached a predetermined speed of rotation and, in this respect, has the same object as the invention of the present application but with a mechanism of an entirely different nature. In the case of this U.S.
patent, each weight is in the form of one or two rollers mounted on a stub shaft imprisoned in a groove formed in a guide flange solid with and projecting rearwardly of the displaceable pulley cheek. The groove is rearwardly open toward a cam ramp, along which the centrifugal roller is to be guidedr and has an upper slightly inclined edge intended to permit the roller to move out of the groove when the drive shaft has reached a certain predetermined speed of rotatiGn to thereby be allowed to rapidly move radially outwardly with respect to the drive shaft and, by moving along the cam ramp, cause the displaceable pulley cheek to be projected rapidly toward the other pulley cheek, -~2~2559 in known fashion. It is seen that while full centrifugal impact of the weights is obtained only when they move out of their respective grooves, they nevertheless start to move radially outward as soon as the drive shaft starts to rotate by their stub shaft riding on the lightly upwardly inclined edge, above-mentioned, over the grooves. This is a first drawback since the belt is likely to start rotating untimely if the engine idles too long. Additionally, the speed of rotation of the drive shaft at which the weights become free of the grooves depends on the specific inclination of the said slightly upwardly inclined edge so that said drive shaft speed becomes intimately associated to this inclination and there is no way of changing it except by changing the inclination. In other words, the driver of the vehicle has no control over the start-up speed of the engine at which the racing vehicle starts to move and this is a drawback in the case o~ a racing vehicle.
The present invention avoids the above dis-advantages by providing the V-shaped pulley clutch having a drive shaft, a pulley cheek mounted on the drive shaft for slidable movement along the shaft which engages the clutch, a cam ramp secured to the drive shaft in spaced relation with the slidable pulley cheek, centrifugal weight means including at least two centrifugal weights moveable radially outwardly between the camp ramp and the pulley cheek to push the cheek away from the ramp, the V-shaped pulley clutch of the present invention being an improvement thereover by the shaft being formed with a circumferential groove and the V-shaped pulley clutch additionally comprising means on the pulley cheek cooperating with the groove on the drive shaft to allow the slidable movement of the pulley cheek and engagement of the clutch only when the drive , lZ~;~55~
.
shaft exceeds a predetermined speed of rotation, this slidable movement allowing means compri'sing, essentially, a sleeve solid with the moveable cheek ,and extending over the drive shaft and at least one detent mechanism, : 5 on the sleeve, including a detent member and means radially pressing the said detent member into th~ groove with a force which is suitable to hold the sleeve and the pulley cheek stationary with respect to the drive shaft until the latter rotates at a speed which exceeds ~ 10 the aforesaid predetermined speed at which time the : centrifugal weights exert, on the ramp and on the moving cheek, a separation force sufficient to release the pulley cheek and to allow the aforesaid slideable movement thereof for engagement of the clutch.
A better understanding of the invention will be afforded by the description that follows of a preferred embodiment having reference to the appended drawing wherein:
Figure 1 is an axial cross-sectional view of a V-shaped pullèy clutch made according to the invention and shown in holding position of the slidable pulley cheek;
Figure 2 is a view similar to that of Figure 1 but showing the moveable pulley cheek in released condition, pressing the V-belt outwardly of the pulley groove;
Figure 3 is a transverse cross-sectional view taken in a plane along line III-III of Figure 1, and .
Figure 4 is a graph showing two curves of the torque-RPM relationship.
Referring to the drawings, there is shown a drive shaft 1 having an end portion 3 made solid therewith in any known manner such as by having a conical : bore 5 receiving the conical end of the shaft 1, the two being secured together by means of a bolt 9 12~559 extending freely thro~gh an axial bore 11 of the end portion 3, the threaded end of the bolt 9 being screwed into a likewise threaded bore 1.3 of the drive shaft 1. In this way, reference will only be made hereinafter to the drive shaft 1 for the transmission of power from the engine (not shown) rotating the drive shaft 1.
The V-shaped pulley clutch has a stationary cheek 15 fast with the shaft 1 as by its welding onto the end portion 3 and a second cheek 17 which is mounted on the drive shaft 1 for axial movement therealong and with respect to the stationary cheek 15. For this purpose, the cheek 17 extends solidly rearwardly away from the stationary cheek 15 into a sleeve 19 mounted for free rotation and axial displacement over the drive shaft 1. The sleeve 19 is formed of an outer part 21 which defines an annular forwardly opened chamber 23 for the reception of one end of a spring 25 to which reference will be made further hereinafter. Secured to this outer sleeve part 21 as by means of a plurality of bolts 27 ; is an inner sleeve part 29 loosely circumscribing the drive shaft 1 (through its end portion 3).
As shown, a cam ramp 31 is secured at the rear end of the drive shaft 1 by means of the bolt 9;
the head 33 thereof and a washer 35 pressing the cam ramp 31 against the terminal end of the end portion 3 to make it solid with the drive shaft 1.
The cam ramp 31 bends forwardly into a frusto-conical guide member 37 which faces a likewise frusto-conical guide member 39 solid with the axially slidablecheek 17. The two guide members 37, 39 thus define an annular chamber, frusto-conical in cross-section, receiving centrifugal weights 41 loosely mounted therein and that are part of centrifugal weight means suitable to allow the weights 41 to move radially outwardly 25~
between the guide members 37, 39.
As shown, the previously mentioned spring 25 is mounted at one end within the recess formed by the annular chamber 23 while the other end bears against one face of a thrust ring 43 of which the other face is applied against a bushing 45, the latter being loosely mounted over the shaft 1.
The above-described V-shaped pulley clutch is of the type shown in the previously mentioned U.S.
patent No. 3,659,470. In known manner, it is used in power transmissions interconnecting a drive shaft such as 1 and a driven shaft (not shown) each shaft having a pulley including a pair of opposed separable radial cheeks, such as 15, 17, defining therebetween a V-groove receiving a likewise V-shaped belt 47 which connects the two pulleys. At idling speed of the engine having the drive shaft 1, the belt 47 lies freely at the bottom of the groove of the drive sh~ft pulley and over the freely rotatable bushing 45 that prevents it from heating. At the same time, the belt 47 lies at the top of the groove of the driven shaft pulley (not shown). One cheek of each pulley is mounted to move toward the other cheek against the force of a bias, such as spring 25. The moveable cheek 17 on the drive shaft 1 is, as aforesaid, acted upon by the centrifugal mechanism aforedescribed and responds to the centrifugal weights 41, moving radially outwardly under the centrifugal force that they develop as the drive shaft 1 picks up speed. In accordance with this weight movement, the moveable cheek 17 is displaced toward the stationary cheek 15 so that the V-groove of the drive shaft pulley closes in, forcing the belt 45 outwardly while the belt in the driven shaft pulley is simultaneously driven in. In this manner, and as it is known, the low speed high torque 5 originally applied by the drive shaft is gradually lZ~2SS9 changed into a high speed low torque for cruising condition of the vehicle.
The embodiment shown in Figures 1, 2 and 3 includes the improvement made according to the invention which resides in the provision of means on the pulley cheek which cooperate with a circumferential groove 49 on the drive shaft 1 to allow the slidable movement of the pulley cheek 17 and engagement of the clutch but only when the drive shaft 1 has exceeded a predetermined speed of rotation.
This is achieved by providing,on and through the rearward end of the sleeve 19, at least one detent mechanism 51 including a detent member 53 radially biassed into the groove 49 with a force suitable to hold the sleeve l9,-and thus the pulley cheek 17, axially stationary with respect to the drive shaft 1 until the latter rotates at a speed exceeding a predetermined speed at which time the centrifugal weights 41 then exert on the guide members 37, 39, respectively of the guide ramp 31 and cheek 17, a separation force which is sufficient to overcome the bias acting on the detent member 53 to thereby allow release of the pulley cheek 17 and its movement toward the stationary cheek 15 for engagement of the clutch.
The detent mechanism 51 of the shown embodiment further comprises a hole 5S of which the top portion is tapped and into which is screwed a threaded plug 57 bearing against a resilient pad 59, the latter biassing the detent member 53 and the rorce of this bias depending of course on the amount of pressure applied by the screwable plug 57 on the resilient pad 59.
As will be gathered, the lateral component of the force developed by the centrifugal weights 41, axially of the shaft 1, can be made to be resisted by the bias of the detent mechanism up to a certain speed ~Z~2559 o~ rotation of the 6haft 1. Beyond that speed of rotation, the resilien~ pad 59 will no longer be able to retain the detent member 53 in the groove 49 so that the sleeve 19 and cheek 17 solid therewith will suddenly and rapidly move frontward toward the stationary cheek 15, allowing a sudden start of the vehicle which will then lunge forward. The resisting situation of the detent mechanism 51 is that shown in Figure 1 while ~he relased situation is that shown in Figure 2.
The embodiment shown in Figure 3 illustrates the use of three detent mechanisms each of which being intended to resist one third of the active axial component of the centrifugal force. More such detent mechanisms 51 may of course be envisioned~
The resilient pad 59 may be made of any suitable resilient material such as rubber. Similarly, it may be replaced by short springs ~not shown). The detent member 53 may consist of one ball (as shown) or of two balls located one above the other in each hole. The advantage of using two or more superimposed balls in every hole 55 is to replace the frictional, rubber-to-metal contact between the pad 5~ and the ball 53 biased into the groove 49 by a less frictional, metal-to-metal contact between the ball engaging the groove 49 and the other ball located over it in the hole.
Reference to the graph of Figure 4 illustrates the development of the torque on a pulley clutch not pro-vided with any means as described to force engagement of the clutch only at a predetermined speed of rotation of the engine drive shaft. A curve A shows that the applied torque only gradually increases the speed of the vehicle and is therefore not suitable for racing. With detent mechanisms as described above, it is possible to increase appreciably the rotary speed of the engine without any ~2~2559 torque being applied to the driven shaft. As soon as the drive sha~t has reached a predetermined speed or rotation, depending on the strength of the bias applied to the detent ; members, a slightly greater speed will develop a centri-fugal force in the centrifugal weights sufficient to over-come the detent mechanisms and allow the moveable cheek extremely rapidly moving toward the stationary cheek thereby rapidly transforming the high torque of the engine into a high speed of the driven shaft. This is illustrated by curve B.
-- .10 --."
._
2,709,372 and 3,~85,366 are of interest here and will be analyzed hereinafter.
U.S. patent n 2,709,372 discloses a V-belt sheave mounted on a drive shaft through an outer sleeve freely rotatable on an inner sleeve secured over the drive shaft, the outer sleeve being axially displaceable with respect to the drive shaft. The sheave has one cheek fixed to the sleeve while the other cheek moves with respect to the sleeve so as to be movable toward and away from the fixed cheek. This movement is applied by means of a known centrifugal weight clutching device.
The outer sleeve has, at one end, a clutch plate with axial dogs engageable in dog recesses of a further clutch plate secured to the drive shaft and the inner sleeve.
Energizing of the V--belt of the sheave, between the cheeks, is obtained by manually sliding the slideable 55~
sleeve and cheeks mounted thereon bodiLy until the axial dogs engage in the receiving dog recesses. This manual bodily displacement of the outer sleeve and sheave is con-trolled by means of a lock spring ball detent of the fixed cheek making it possible for the ball of the detent to move into one of two peripheral grooves of the drive shaft inner sleeve. This construction and arrangement which works independently of the rotational speed of the drive shaft, is intended to prevent chafting of the belt in idling position and is no way intended, nor does the disclosure make any suggestion to that effect/ to pxovide for sudden coupling of the sheave cheeks and belt together to give a likewise sudden start to the vehicle being driven through the belt.
U.S. patent n~ 3,685,366 relates to a racing centrifuyal clutch assembly which is provided for inhibit-ing the radial movement of its centrifugal weights that are used to move the displaceable cheek toward the other cheek until the drive shaft has reached a predetermined speed of rotation and, in this respect, has the same object as the invention of the present application but with a mechanism of an entirely different nature. In the case of this U.S.
patent, each weight is in the form of one or two rollers mounted on a stub shaft imprisoned in a groove formed in a guide flange solid with and projecting rearwardly of the displaceable pulley cheek. The groove is rearwardly open toward a cam ramp, along which the centrifugal roller is to be guidedr and has an upper slightly inclined edge intended to permit the roller to move out of the groove when the drive shaft has reached a certain predetermined speed of rotatiGn to thereby be allowed to rapidly move radially outwardly with respect to the drive shaft and, by moving along the cam ramp, cause the displaceable pulley cheek to be projected rapidly toward the other pulley cheek, -~2~2559 in known fashion. It is seen that while full centrifugal impact of the weights is obtained only when they move out of their respective grooves, they nevertheless start to move radially outward as soon as the drive shaft starts to rotate by their stub shaft riding on the lightly upwardly inclined edge, above-mentioned, over the grooves. This is a first drawback since the belt is likely to start rotating untimely if the engine idles too long. Additionally, the speed of rotation of the drive shaft at which the weights become free of the grooves depends on the specific inclination of the said slightly upwardly inclined edge so that said drive shaft speed becomes intimately associated to this inclination and there is no way of changing it except by changing the inclination. In other words, the driver of the vehicle has no control over the start-up speed of the engine at which the racing vehicle starts to move and this is a drawback in the case o~ a racing vehicle.
The present invention avoids the above dis-advantages by providing the V-shaped pulley clutch having a drive shaft, a pulley cheek mounted on the drive shaft for slidable movement along the shaft which engages the clutch, a cam ramp secured to the drive shaft in spaced relation with the slidable pulley cheek, centrifugal weight means including at least two centrifugal weights moveable radially outwardly between the camp ramp and the pulley cheek to push the cheek away from the ramp, the V-shaped pulley clutch of the present invention being an improvement thereover by the shaft being formed with a circumferential groove and the V-shaped pulley clutch additionally comprising means on the pulley cheek cooperating with the groove on the drive shaft to allow the slidable movement of the pulley cheek and engagement of the clutch only when the drive , lZ~;~55~
.
shaft exceeds a predetermined speed of rotation, this slidable movement allowing means compri'sing, essentially, a sleeve solid with the moveable cheek ,and extending over the drive shaft and at least one detent mechanism, : 5 on the sleeve, including a detent member and means radially pressing the said detent member into th~ groove with a force which is suitable to hold the sleeve and the pulley cheek stationary with respect to the drive shaft until the latter rotates at a speed which exceeds ~ 10 the aforesaid predetermined speed at which time the : centrifugal weights exert, on the ramp and on the moving cheek, a separation force sufficient to release the pulley cheek and to allow the aforesaid slideable movement thereof for engagement of the clutch.
A better understanding of the invention will be afforded by the description that follows of a preferred embodiment having reference to the appended drawing wherein:
Figure 1 is an axial cross-sectional view of a V-shaped pullèy clutch made according to the invention and shown in holding position of the slidable pulley cheek;
Figure 2 is a view similar to that of Figure 1 but showing the moveable pulley cheek in released condition, pressing the V-belt outwardly of the pulley groove;
Figure 3 is a transverse cross-sectional view taken in a plane along line III-III of Figure 1, and .
Figure 4 is a graph showing two curves of the torque-RPM relationship.
Referring to the drawings, there is shown a drive shaft 1 having an end portion 3 made solid therewith in any known manner such as by having a conical : bore 5 receiving the conical end of the shaft 1, the two being secured together by means of a bolt 9 12~559 extending freely thro~gh an axial bore 11 of the end portion 3, the threaded end of the bolt 9 being screwed into a likewise threaded bore 1.3 of the drive shaft 1. In this way, reference will only be made hereinafter to the drive shaft 1 for the transmission of power from the engine (not shown) rotating the drive shaft 1.
The V-shaped pulley clutch has a stationary cheek 15 fast with the shaft 1 as by its welding onto the end portion 3 and a second cheek 17 which is mounted on the drive shaft 1 for axial movement therealong and with respect to the stationary cheek 15. For this purpose, the cheek 17 extends solidly rearwardly away from the stationary cheek 15 into a sleeve 19 mounted for free rotation and axial displacement over the drive shaft 1. The sleeve 19 is formed of an outer part 21 which defines an annular forwardly opened chamber 23 for the reception of one end of a spring 25 to which reference will be made further hereinafter. Secured to this outer sleeve part 21 as by means of a plurality of bolts 27 ; is an inner sleeve part 29 loosely circumscribing the drive shaft 1 (through its end portion 3).
As shown, a cam ramp 31 is secured at the rear end of the drive shaft 1 by means of the bolt 9;
the head 33 thereof and a washer 35 pressing the cam ramp 31 against the terminal end of the end portion 3 to make it solid with the drive shaft 1.
The cam ramp 31 bends forwardly into a frusto-conical guide member 37 which faces a likewise frusto-conical guide member 39 solid with the axially slidablecheek 17. The two guide members 37, 39 thus define an annular chamber, frusto-conical in cross-section, receiving centrifugal weights 41 loosely mounted therein and that are part of centrifugal weight means suitable to allow the weights 41 to move radially outwardly 25~
between the guide members 37, 39.
As shown, the previously mentioned spring 25 is mounted at one end within the recess formed by the annular chamber 23 while the other end bears against one face of a thrust ring 43 of which the other face is applied against a bushing 45, the latter being loosely mounted over the shaft 1.
The above-described V-shaped pulley clutch is of the type shown in the previously mentioned U.S.
patent No. 3,659,470. In known manner, it is used in power transmissions interconnecting a drive shaft such as 1 and a driven shaft (not shown) each shaft having a pulley including a pair of opposed separable radial cheeks, such as 15, 17, defining therebetween a V-groove receiving a likewise V-shaped belt 47 which connects the two pulleys. At idling speed of the engine having the drive shaft 1, the belt 47 lies freely at the bottom of the groove of the drive sh~ft pulley and over the freely rotatable bushing 45 that prevents it from heating. At the same time, the belt 47 lies at the top of the groove of the driven shaft pulley (not shown). One cheek of each pulley is mounted to move toward the other cheek against the force of a bias, such as spring 25. The moveable cheek 17 on the drive shaft 1 is, as aforesaid, acted upon by the centrifugal mechanism aforedescribed and responds to the centrifugal weights 41, moving radially outwardly under the centrifugal force that they develop as the drive shaft 1 picks up speed. In accordance with this weight movement, the moveable cheek 17 is displaced toward the stationary cheek 15 so that the V-groove of the drive shaft pulley closes in, forcing the belt 45 outwardly while the belt in the driven shaft pulley is simultaneously driven in. In this manner, and as it is known, the low speed high torque 5 originally applied by the drive shaft is gradually lZ~2SS9 changed into a high speed low torque for cruising condition of the vehicle.
The embodiment shown in Figures 1, 2 and 3 includes the improvement made according to the invention which resides in the provision of means on the pulley cheek which cooperate with a circumferential groove 49 on the drive shaft 1 to allow the slidable movement of the pulley cheek 17 and engagement of the clutch but only when the drive shaft 1 has exceeded a predetermined speed of rotation.
This is achieved by providing,on and through the rearward end of the sleeve 19, at least one detent mechanism 51 including a detent member 53 radially biassed into the groove 49 with a force suitable to hold the sleeve l9,-and thus the pulley cheek 17, axially stationary with respect to the drive shaft 1 until the latter rotates at a speed exceeding a predetermined speed at which time the centrifugal weights 41 then exert on the guide members 37, 39, respectively of the guide ramp 31 and cheek 17, a separation force which is sufficient to overcome the bias acting on the detent member 53 to thereby allow release of the pulley cheek 17 and its movement toward the stationary cheek 15 for engagement of the clutch.
The detent mechanism 51 of the shown embodiment further comprises a hole 5S of which the top portion is tapped and into which is screwed a threaded plug 57 bearing against a resilient pad 59, the latter biassing the detent member 53 and the rorce of this bias depending of course on the amount of pressure applied by the screwable plug 57 on the resilient pad 59.
As will be gathered, the lateral component of the force developed by the centrifugal weights 41, axially of the shaft 1, can be made to be resisted by the bias of the detent mechanism up to a certain speed ~Z~2559 o~ rotation of the 6haft 1. Beyond that speed of rotation, the resilien~ pad 59 will no longer be able to retain the detent member 53 in the groove 49 so that the sleeve 19 and cheek 17 solid therewith will suddenly and rapidly move frontward toward the stationary cheek 15, allowing a sudden start of the vehicle which will then lunge forward. The resisting situation of the detent mechanism 51 is that shown in Figure 1 while ~he relased situation is that shown in Figure 2.
The embodiment shown in Figure 3 illustrates the use of three detent mechanisms each of which being intended to resist one third of the active axial component of the centrifugal force. More such detent mechanisms 51 may of course be envisioned~
The resilient pad 59 may be made of any suitable resilient material such as rubber. Similarly, it may be replaced by short springs ~not shown). The detent member 53 may consist of one ball (as shown) or of two balls located one above the other in each hole. The advantage of using two or more superimposed balls in every hole 55 is to replace the frictional, rubber-to-metal contact between the pad 5~ and the ball 53 biased into the groove 49 by a less frictional, metal-to-metal contact between the ball engaging the groove 49 and the other ball located over it in the hole.
Reference to the graph of Figure 4 illustrates the development of the torque on a pulley clutch not pro-vided with any means as described to force engagement of the clutch only at a predetermined speed of rotation of the engine drive shaft. A curve A shows that the applied torque only gradually increases the speed of the vehicle and is therefore not suitable for racing. With detent mechanisms as described above, it is possible to increase appreciably the rotary speed of the engine without any ~2~2559 torque being applied to the driven shaft. As soon as the drive sha~t has reached a predetermined speed or rotation, depending on the strength of the bias applied to the detent ; members, a slightly greater speed will develop a centri-fugal force in the centrifugal weights sufficient to over-come the detent mechanisms and allow the moveable cheek extremely rapidly moving toward the stationary cheek thereby rapidly transforming the high torque of the engine into a high speed of the driven shaft. This is illustrated by curve B.
-- .10 --."
._
Claims (10)
1. A V-shaped pulley clutch, for a racing vehicle, including a drive shaft, a pulley cheek mounted on said drive shaft for slidable movement along said shaft for engagement of said clutch, a cam ramp secured to said drive shaft in spaced relationship with said slidable pulley cheek, centrifugal weight means including at least two centrifugal weights movable radially outwardly between said cam ramp and said pulley cheek to push said cheek away from said ramp, the improvement wherein said drive shaft is formed with a circumferential groove and said V-shaped pulley clutch additionally comprises means on said pulley cheek cooperating with said groove on said shaft to allow said slidable movement of said pulley cheek and engagement of said clutch only when said drive shaft has exceeded a predetermined speed of rotation, said slidable movement allowing means com-prising:
- a sleeve solid with said movable pulley cheek and extending over said drive shaft;
- at least one detent mechanism on said sleeve including a detent member and means radially pressing said detent member into said groove with a force suitable to hold said sleeve and pulley cheek stationary with respect to said drive shaft until said drive shaft rotates at a speed exceeding said predetermined speed at which time said centrifugal weights exert on said ramp and on said movable cheek a separation force sufficient to release said pulley cheek and allow said slidable movement thereof for engagement of said clutch.
- a sleeve solid with said movable pulley cheek and extending over said drive shaft;
- at least one detent mechanism on said sleeve including a detent member and means radially pressing said detent member into said groove with a force suitable to hold said sleeve and pulley cheek stationary with respect to said drive shaft until said drive shaft rotates at a speed exceeding said predetermined speed at which time said centrifugal weights exert on said ramp and on said movable cheek a separation force sufficient to release said pulley cheek and allow said slidable movement thereof for engagement of said clutch.
2. A clutch as claimed in claim 1, wherein said pulley sleeve is formed with a radial through bore, said detent member is at the bottom of said hole in con-tact with said drive shaft, and wherein said detent mechanism further comprises, in said hole: a resilient member over said detent member and a plug over said resilient member closing said hole and pressing on said resilient member so that said resilient member applies a resilient bias, on said detent member, equal to said sleeve holding force.
3. A clutch as claimed in claim 2, wherein said hole has a tapped portion at the top thereof and said plug is outwardly threaded and screwed in said tapped portion, said plug being further screwable from outside said sleeve to allow adjustment of said resilient bias.
4. A clutch as claimed in claim 3, wherein said detent member is made of at least one ball and said groove is about half circular in cross-section suitable to receive said at least one ball.
5. A clutch as claimed in claim 1, wherein said sleeve is formed with a plurality of such through holes evenly spaced therearound and said sleeve comprises a plurality of detent mechanisms equal in number to that of said through holes, each detent mechanism comprising, in one of said holes: a resilient member over said detent member and a plug over said resilient member closing said holes and pressing on said resilient member so that said resilient member applies a resilient bias on said detent member, the sum of the resilient biasses of said detent mechanisms being equal to said sleeve holding force.
6. A clutch as claimed in claim 5, wherein each hole has a tapped portion at the top thereof and said plug is outwardly threaded and screwed in said tapped portion, said plug being further screwable from outside said sleeve to allow adjustment of said resilient bias.
7. A clutch as claimed in claim 6, wherein each detent member is made of at least one ball and said groove is about half circular in cross-section suitable to receive said at least one ball.
8. A clutch as claimed in claim 7, wherein said through holes and detent mechanisms are at least three in number.
9 A clutch as claimed in claim 2, wherein said resilient member is a pad made of resilient material.
10. A clutch as claimed in claim 5, wherein said resilient member is a pad made of resilient material.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000462301A CA1212559A (en) | 1984-08-31 | 1984-08-31 | V-shaped pulley clutch for racing vehicles |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000462301A CA1212559A (en) | 1984-08-31 | 1984-08-31 | V-shaped pulley clutch for racing vehicles |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1212559A true CA1212559A (en) | 1986-10-14 |
Family
ID=4128632
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000462301A Expired CA1212559A (en) | 1984-08-31 | 1984-08-31 | V-shaped pulley clutch for racing vehicles |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1212559A (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0437157A1 (en) * | 1990-01-12 | 1991-07-17 | Société Canadienne POWERBLOC IBC Canada | Pulley for continuously variable transmission, with a torque transmitting membrane |
| FR2657406A1 (en) * | 1990-01-25 | 1991-07-26 | Ibc Europ Sarl | Pulley for a transmission with automatic speed variation |
| FR2664012A1 (en) * | 1990-06-28 | 1992-01-03 | Ibc Europ Sarl | Driving pulley equipped with anti-noise elements |
| FR2671596A1 (en) * | 1991-01-16 | 1992-07-17 | Ibc Europ Eurl | AUTOMATIC SPEED DRIVE PULLEY. |
| WO1993006388A1 (en) * | 1991-09-27 | 1993-04-01 | Ibc Powerbloc Canada | Driving pulley in a variable-speed belt drive having toothed flyweights |
| US5458539A (en) * | 1994-08-12 | 1995-10-17 | Powerbloc Ibc Canada Inc. | Flyweight with a lateral knob |
-
1984
- 1984-08-31 CA CA000462301A patent/CA1212559A/en not_active Expired
Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0437157A1 (en) * | 1990-01-12 | 1991-07-17 | Société Canadienne POWERBLOC IBC Canada | Pulley for continuously variable transmission, with a torque transmitting membrane |
| FR2657132A1 (en) * | 1990-01-12 | 1991-07-19 | Ibc Europ Eurl | SPEED DRIVE PULLEY EQUIPPED WITH A TRANSMISSION MEMBRANE. |
| FR2657406A1 (en) * | 1990-01-25 | 1991-07-26 | Ibc Europ Sarl | Pulley for a transmission with automatic speed variation |
| FR2664012A1 (en) * | 1990-06-28 | 1992-01-03 | Ibc Europ Sarl | Driving pulley equipped with anti-noise elements |
| FR2671596A1 (en) * | 1991-01-16 | 1992-07-17 | Ibc Europ Eurl | AUTOMATIC SPEED DRIVE PULLEY. |
| EP0495740A1 (en) * | 1991-01-16 | 1992-07-22 | Société Canadienne POWERBLOC IBC Canada | Pulley for a speed variator |
| WO1993006388A1 (en) * | 1991-09-27 | 1993-04-01 | Ibc Powerbloc Canada | Driving pulley in a variable-speed belt drive having toothed flyweights |
| FR2681928A1 (en) * | 1991-09-27 | 1993-04-02 | Powerbloc Ibc Canada Inc | DRIVING PULLEY OF A VARIABLE SPEED BELT TRANSMISSION EQUIPPED WITH TOOTHED MASSELOTS. |
| US5514040A (en) * | 1991-09-27 | 1996-05-07 | Powerbloc Ibc Canada Inc. | Variable-speed belt drive having toothed flyweights |
| US5458539A (en) * | 1994-08-12 | 1995-10-17 | Powerbloc Ibc Canada Inc. | Flyweight with a lateral knob |
| WO1996005454A1 (en) * | 1994-08-12 | 1996-02-22 | Powerbloc Ibc Canada, Inc. | Flyweight with a lateral knob |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |