FR2623264A1 - BELT TRANSMISSION FOR A SELF-PROPELLED WORKING VEHICLE DRIVEN BY AN OPERATOR FOLLOWING THE MACHINE ON FOOT, ESPECIALLY FOR A MOTOR - Google Patents

Abstract

A tiller consists of an E motor at the front and a transmission box at the rear. The motor shaft 4 and the input shaft 7 of the transmission housing project laterally from the chassis of the vehicle and are interconnected by a belt transmission 12 of the continuously variable type. The driving pulley 5 of this transmission is expandable, so that the transmission constitutes at the same time a speed change device. The control member 14, the rotation of which in one direction or the other makes it possible to change the forward speed of the machine, is installed inside the front and lateral limits of the vehicle, defined by a bonnet 21 and by a belt housing 20. An automatic tension pulley 10 is combined with a guide pulley 11 of the belt 12 to obtain a compact transmission with a large range of continuous speed adjustment.

Description

The present invention relates to a transmission for a vehicle

  work followed on foot by the driver, who could also walk in front of or next to the machine, comprising a motor installed at the front end of the vehicle chassis and from which laterally exceeds an output shaft, as well as a shaft input of a transmission box for advancement, this box being

  installed at the rear of the engine and its input shaft being equally

  laterally oriented, i.e. transversely to the direction of travel, on the same side as the shaft

engine.

  A machine of this type is known, for example by the Japanese utility model published under the number 57-47421. This vehicle has a forward drive which has multiple drive belts passing around a drive shaft and a drive input shaft and each providing a different drive ratio, as well as combined tension pulleys with the different belts and brought selectively into contact with them in order to obtain a desired transmission ratio; this transmission acts at the same time as a device

  gear change for advancement.

  However, as the speed change is carried out in stages with this transmission, the fine adjustment of the vehicle speed is impossible. In addition, to extend the range in which the vehicle speed is adjustable, it is necessary to increase the number of transmission belts, which requires increasing the axial dimension of the motor shaft and / or the input shaft. of

transmission box.

  In view of this state of the art, the invention aims firstly to provide a compact transmission capable of allowing the adjustment of the forward speed over a wide range and which also acts as a fine-tuning gear change device , the transmission must also ensure

  - greater security than known transmissions.

  - To this end, according to the invention, a transmission for a self-propelled work vehicle driven by a foot operator comprises a motor installed at the front end of the chassis of the

  vehicle, covered by a bonnet and whose shaft extends beyond the

  frame, as well as a transmission box installed at the rear of the engine and provided with an input shaft which projects laterally from the frame in the same direction as the engine shaft, and is characterized in that an expandable driving pulley is mounted on the drive shaft and a non-expandable driven pulley is wedged on the input shaft of the transmission housing, that a transmission belt is arranged around the driving and driven pulleys for

  transmit motive energy from the engine to the transmission unit

  sion, the belt being covered by a casing, and a control member is provided for varying the radius of winding of the belt on the driving pulley, the control member being placed at the front of the belt casing, at the rear of the front end of the engine hood, as well as recessed, towards the chassis of the vehicle, relative to the external lateral limit of the belt housing,

on the side of the motor shaft.

  The functions and effects of this construction will

described in the following.

  The operation of the control member changes the radius

  of winding the belt with respect to the motor shaft, i.e.

  say on the driving pulley, which also changes the transmission ratio between the motor shaft and the input shaft of the transmission-box. In other words, the transmission between the engine

  and the gearbox acts at the same time as a dispo-

gear change.

  The variation of the winding radius can be carried out with multiple bearings or continuously, which allows, in one case

  as in the other, to reduce the number of transmission belts

  while increasing the number of speed steps or

  performing a continuous gear change.

  In addition, since the control member for producing the gear change is set back both from the front end of the engine hood and from the outer lateral limit of the belt housing, the advantage is obtained

  that the risk of inadvertent contact - and could be dangerous -

  reux - between the control unit and surrounding objects, such as

  than plants, shrubs or the like, is reduced.

  The result is that the transmission according to the invention, while retaining the known advantages of a belt type transmission acting at the same time as a speed change device, can be produced in a compact form, without this requiring increase the axial dimension of the drive shaft and / or the input shaft of the gearbox, since fine adjustment of the speed is possible over a wide range by a small

  movement of the movable flange of the expanding pulley.

  Thanks to the recessed arrangement of the operating member for the gear change, limiting the risk of accidental contact with surrounding objects, the safety of the machine is increased both during operation and during

its storage.

  According to a preferred embodiment of the invention, the variation of the winding radius by the control member takes place in cooperation with an automatic tension pulley which flexes the transmission belt. It is possible to provide, in addition, between the expanding pulley and the automatic tensioning pulley or between the latter and the non-expanding pulley, a guide pulley to support the belt in the opposite direction to the deflection

  of the belt by the tension pulley.

  More specifically, in the prior art, an automatic tension pulley alone compensates for the length of a belt, during speed changes, on a strand of belt between the pulleys. With the construction according to the invention, on the contrary, this length compensation is carried out on a portion of belt comprised between the driving pulley or the driven pulley and the belt guide pulley. This amounts to saying that the length of the belt to be compensated for by the displacement of the automatic tension pulley becomes shorter, of a length corresponding to that of the portion of belt situated between the guide pulley and the driving pulley or the driven pulley. in the absence of an automatic tension pulley between them. It thus becomes possible to control a longer portion of the belt despite the fact that the tension pulley stroke is

relatively small.

  More precisely, thanks to the presence of the guide pulley, it becomes possible to increase the length of the belt capable of being compensated with respect to the stroke of the tension pulley. Therefore, in a system where the tension pulley flexes the belt towards the inside of the loop formed by the belt, the range in which the speed can be varied, corresponding to the operating stroke of the control member, can be extended in safety, while avoiding contact between the leading strand and the return strand of the belt. In a transmission where the tension pulley flexes the belt towards the outside of the formed loop

  through it the speed adjustment range can also be extended

  while minimizing the outward projection of the belt. To summarize, the device which has just been described also contributes to the compactness of the transmission and to obtaining

an extended speed range.

  Other characteristics and advantages of the invention

  will emerge more clearly from the following description of a

  nonlimiting example of embodiment, as well as annexed drawings, in which:

  - Figure 1 is a side view of the assembly of a motocul-

  tor comprising a transmission according to the invention; - Figure 2 is a section on a larger scale of this transmission, forming at the same time gear change device, the section passing through the motor shaft and the input shaft of the transmission housing; and

  - Figure 3 is a side view of the transmission / change-

speed.

  FIG. 1 represents a self-propelled vehicle of the type in question here, in this case a tiller, which comprises a chassis carried by two wheels 1, a motor E installed at the front of the chassis, one or two handlebars 2 pivotally mounted around a vertical axis P on the rear part of the chassis, so that they can be pivoted forwards and backwards, as

2-623264

  illustrated by The position in dashed lines and The position in solid line, as well as a coupling 3 for the coupling of different

  tools, such as a rotary cultivator for example.

  Referring now to Figures 2 and 3, a

  driving pulley 5 of the expandable type is mounted integral in rotation with

  tion on the output shaft or motor shaft 4, protruding laterally-

  ment of the vehicle chassis, of the engine E. A non-expandable pulley 9 constitutes the driven pulley, which is wedged on an input shaft 7 of a transmission box 6 installed at the rear of the engine E, the shaft d entry 7 also protruding from the chassis of the vehicle in the transverse direction to advancement. The pulley 9 also acts as the body of a main clutch 8 with multiple discs. A transmission belt 12 passes around the pulleys and 9, an automatic tension pulley 10 and a guide pulley 11. During operation, by operating a control member 14 connected to the motor E by a support 13, we changes the winding radius of the belt 12 on the pulley 5, which produces a speed change. The whole construction which has just been described constitutes a continuous gear shifting device of the belt type, forming a shift system.

  auxiliary speed for advancement.

  More specifically, the control member 14 is mounted in the support 13 so that it can be rotated relative to it, but without being able to move in the axial direction. The member 14 acts on a pulley control arm 17 by means of a connecting element or attachment 15. The latter is mounted by one end

  on a threaded rod 14a of the control member 14 and is articulated

  abutment by its opposite end on a pivot rod 16.

  In service, when the control member 14 is rotated in one direction or the other, the fastener 15 advances or retreats along the axis of rotation of the member 14 and rotates in one direction or the other. a pivot 18 carrying the control arm 17. The movement of this arm causes the movable flange 5a of the pulley 5 to slide on the axis of rotation of this pulley, by approaching or removing it

  of the fixed flange 5b, in cooperation with a spring 19.

  As regards more particularly the location of the control member 14 for the gear change, it can be seen that this member is placed in front of a belt casing 20 which covers the transmission belt 12, as well as pulleys 5 and 9, for accident prevention. It can also be seen that the control member 14 is set back both from the front end of the engine cover 21, towards the rear

  of the vehicle chassis, and in relation to the external lateral limit

  of the belt housing 20. This location is advantageous to avoid any protrusion of the control member 14, which can cause untimely and dangerous contact of this member with

surrounding objects.

  As can be seen in Figures 2 and 3, an index member 22 is connected to the clip 15 and moves together with it. The element 22 has a window in which an index 22a appears which is also connected to the element 22. On the other hand, the support 13 is provided with a speed display panel 24

  with speed indication characters a, b and c, corresponding

  dant respectively at a high speed (H), an average speed (M) and a low speed (L). These various elements together constitute a speed display of the continuous speed change device. In service, when the control member 14 is turned, the index 22a moves in the window to indicate one of the characters a, b or c (H, M or L) corresponding to the speed

adjusted.

  The transmission also includes a compensating mechanism

  belt length gauge, described below.

  The guide pulley 11, already mentioned, is rotatably mounted at a fixed point on a support 30. The latter is adjustable by rotation about a support axis 31 and it can be immobilized in the adjusted position using a locking screw 32. The pulley 11 is in contact with the internal face of the transmission belt 12 and it supports this belt in the direction directed towards the outside of the loop formed by the belt. The pulley 11 is installed between the driven pulley 9, which is not expandable, and the automatic tension pulley 10. The latter is mounted on the transmission housing 6 by means of a support arm 33 articulated on the support pin 31, so that the tension pulley 10 can

  turn on a part of a circle having as its center the geometrical axis

  support shaft 31. A tension spring 34 acts on the arm 33 to move the pulley 10 towards the inside of the loop formed by the belt 12 and to tension it. Therefore, the automatic tension pulley 10 causes the belt portion between the two supports constituted by the expandable pulley 5 and the guide pulley 11 to bend inwards; this portion of belt is shorter than all The strand extending between the pulleys 5 and 9, which makes it possible to compensate for a relatively long portion of belt by a tension pulley whose stroke is short. As soon as there is a decrease in the radius of winding of the belt 12 on the expandable driven pulley 5, the pulley 10, by bending the belt 12 further towards the inside of the loop formed by it, automatically adjusts the tension of the belt. It is also possible, as a variant, to cause the guide pulley 11 to act between the driving and expanding pulley 5 and the

tension pulley 10.

  In addition, the guide pulley 11 can also be used in a transmission where the automatic tension hen 10 flexes the transmission belt 12 towards the outside of the loop formed by the belt. In this case, the guide pulley 11 must be installed to be in contact with the external face of the

belt 12.

  Although the invention has been described here in relation to

  a tiller, it is also applicable to 2 other vehicles

  work cules, such as a planting machine, a binder, a

  transport vehicle, a vehicle for the combined performance of different

annuities work, and so on.

Claims (5)

  1. Transmission for a self-propelled work vehicle driven by a foot operator, comprising an engine (E) installed at the front end of the vehicle chassis, covered by a bonnet (21) and the shaft (4) of which protrudes side of the chassis, as well as a transmission box (6) installed at the rear of the   motor (E) and provided with an input shaft (7) which projects laterally-   frame in the same direction as the motor shaft (4), character-   laughing in that an expandable driving pulley (5, Sa, 5b) is rotatably mounted on the drive shaft (4) and a non-expandable driven pulley (9) is wedged on the input shaft (7) from the transmission box (6), that a transmission belt (12) is arranged around the driving pulleys (5) and driven (9) to transmit driving energy from the engine (E) to the transmission box (6) , the belt (12) being covered by a casing (20), and that a control member (14) is provided for varying the radius of winding of the belt (12) on the driving pulley (5), the control member (14) being placed at the front of the belt housing (20), behind the front end of the engine cover (21), as well as recessed, towards the chassis of the vehicle, with respect to at the outer lateral limit of the belt housing (20), on the shaft side motor (4).   2. Transmission according to claim 1, wherein the control member (14) is rotatable, while being held fixed in the direction of its axis, and its operation causes displacement a connecting element (15).   3. Transmission according to claim 1 and further comprising an automatic tension pulley (10) for bending and tensioning the transmission belt (12) and a guide pulley (11) rotatably mounted at a fixed point between the driving pulley (5) and the tension pulley (10) to support the belt (12) in the opposite direction to the deflection of the belt by the pulley tension (10).   4. Transmission according to claim 1 and further comprising an automatic tension pulley (10) for bending and tensioning the transmission belt (12) and a guide pulley (11) rotatably mounted at a fixed point between the pulley tension (10) and the driven pulley (9) to press the belt (12) in the opposite direction to the deflection of the belt by the pulley tension (10).   5. Transmission according to claim 3 or 4, wherein the automatic tension pulley (10) is mounted to flex The transmission belt (12) towards the inside of the loop formed by this belt.