GB2295208A

GB2295208A - Positioning pin for a vehicle transmission actuating mechanism

Info

Publication number: GB2295208A
Application number: GB9523561A
Authority: GB
Inventors: Jurgen Decker; Erich Ausprung
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-11-18
Filing date: 1995-11-17
Publication date: 1996-05-22
Anticipated expiration: 2015-11-17
Also published as: GB9523561D0; DE4441138C2; DE4441138A1; ES2127086A1; ES2127086B1; GB2295208B

Description

1 2295208 A positioning pin for a transmission actuatinq mechanism

The invention relates to a positioning pin for a transmission actuating mechanism as specified in the precharacterising clause of Claim 1.

In a gear casing placed in front of the transmission of a motor vehicle, the gear change operations for reverse travel and forward travel and also idling performed at a gearshift lever are normally transmitted via a so-called shift fork to an actuating mechanism for the transmission. In this case the actuating mechanism comprises, in a manner known per se, a so-called intermediate lever in the form of a connecting bush disposed on a shaft, which to adjust the different transmission positions is rotatable on the shaft by the shift fork and in addition is displaceable in the longitudinal direction of the shaft against the force of a spring. The rotation and the axial displacement of the connecting bush is transmitted to the transmission by control elements attached to the connecting bush.

For the f irst adjustment of the transmission, the said connecting bush is normally brought via the shift fork into a predetermined position by axial displacement against the force of the spring and by a rotation on the shaft. In this predetermined position a bore disposed in the walls of the connecting bush is aligned with a bore of the gear casing, with the result that after the insertion of a positioning pin through the bore of the gear casing into the said bore of the connecting bush, the desired position is maintained. In this position predetermined adjustments are performed in the transmission. After these adjustments the positioning pin is removed from the bore of the connecting bush, whereby said bush is released. A normal steel pin, which has to be withdrawn from the bore of the connecting bush after the gearing adjustments, is generally used as a positioning pin.

2 In order to seal the transmission, a sealing bolt then has to be mounted, which is often very difficult to mount because the site of the said bore is not very accessible. A disadvantage of such an adjusting pin lies in that both the manual withdrawal from the bore of the connecting bush and also the pressing in of the sealing bolt are necessary. If, on the other hand, the steel pin is by oversight not removed from the bore of the connecting bush and/or the sealing bolt is afterwards not introduced into the bore, because this has been forgotten, for example, the entire transmission is locked and/or not tight.

The object of the present invention therefore consists in developing a positioning pin in such a manner that in the event of an incorrect manipulation the transmission is prevented from becoming locked or not tight.

This object is achieved by a positioning pin of the type mentioned at the beginning, which is characterised by the

Claims

features given in the characterising part of Claim 1.

A substantial advantage lies in that the positioning pin in accordance with the invention possesses both an energy accumulator, which ensures that, after the performance of the transmission adjustments and the actuation of the gearshift lever or respectively the connecting bush via the shift fork, it is automatically withdrawn from the bore of the connecting bush, so that a locking of the transmission is prevented, and also in combination therewith a sealing device, which ensures an automatic sealing of the transmission after the withdrawal of the positioning pin. In this manner, should the withdrawal of the positioning pin or the insertion of the sealing bolt be forgotten, the transmission is prevented from becoming locked or not tight. The present positioning pin is advantageously designed so that, after removal from the bore of the connecting bush, it is retained in the bore of the gear casing, so that it is 3 ready for further subsequent positioning operations, which are necessary, for example, for subsequent adjustments of the transmission and in the predetermined position of the connecting bush only has to be pushed against the force of the energy accumulator into the bore.

Further advantageous embodiments of the positioning pin according to the invention proceed from the sub-clains.

The invention and its embodiments are explained in further detail below in connection with the figures.

Fig. 1 shows the gear casing with the positioning pin retained in a bore thereof, whereby said pin fixes is the connecting bush in the predetermined position; Fig. 2 shows the positioning pin in the position withdrawn from the bore of the connecting bush and Fig. 3 shows an embodiment of the positioning pin in accordance with the invention.

In Figure 1 the gear casing is designated by 1. The gear change operations performed on the gearshift lever (not represented in further detail) are transmitted to the socalled shift fork 2, which engages with a shifter rod 3 into the interior of the gear casing 1. In a manner not represented in further detail and known per se, the axial displacement of the shifter rod 3 (arrow 31) is converted 30 into a rotation of the connecting bush 4, which is rotatably mounted in the gear casing 1 on the shaft 5. The direction of rotation of the connecting bush 4 is represented by the arrow 41. A rotation of the shifter rod 3 (arrow 32) is converted into an axial displacement of the connecting bush 4 on the shaft 5 against the force of a spring (not represented in further detail). A through-bore 6, through which the positioning pin 7 passes, which is explained in 4 further detail below, is located in the wall of the gear casing 1. When the connecting bush 4 on the shaft 5 is rotated and displaced into a predetermined position, which is prescribed for the performance of certain adjustments at the transmission, a bore 8 of the connecting bush 4 is axially aligned with the through-bore 6, so that the positioning pin 7 can also be inserted into the bore 8 by its front end to maintain the determined position. In this state, the connecting bush 4 and consequently the entire transmission are prevented from performing the adjustments.

After the performance of these adjustments, the front end of the positioning pin 7 shown in Figure 2 can be withdrawn from the bore 8 of the connecting bush 4 so that the connecting bush 4 and consequently also the entire transmission can be released and the transmission can be changed via the shift fork 2 and the connecting bush 4 by actuating the gearshift lever.

As shown in Figure 3, the present positioning pin 7 comprises a shaft 71, a head part 72, a retaining member 73 and an energy accumulator 74.

The retaining member 73 preferably has the form of a tongue part 73 resiliently outwardly protruding over the periphery of the shaft 71, which on the insertion of the positioning pin 7 into the through-bore 6 springs inwards and, when the front end region of the shaft 71 emerges from the through bore 6, springs outwards again, so that the entire positioning pin 7 is captively retained at the wall of the gear casing 1 comprising the through-bore 6.

An energy accumulator is also provided, the function of which lies in biasing the positioning pin 7 in a direction out of the casing 1. In accordance with Figure 3, this energy accumulator preferably has the form of a helical spring, which is located on the shaft 71 preferably between the head part 72 and the tongue part 73. When the positioning pin 7 in accordance with Figure 1 is inserted into the through-bore 6, the helical spring 7 is compressed between the head part 72 and the face of the gear casing 1 turned theretowards, so that it tries to move the positioning pin 7 out of the bore 6 in the direction of arrow 75, until the tongue part 73 preferably abuts the edge region of the inner opening of the through-bore 6.

In order to prevent oil emerging outwardly from the interior of the gear casing 1 through the through-bore 6, the shaft part 1 has a sealing device, preferably a circumferential groove 76, in which an 0-ring seal 77 is retained, which produces a sealing of the through-bore 6 in both possible positions of the positioning pin 7. At first the helical spring 74 is pushed onto the shaft 71 and retained in the space between the head part 72 and the groove 76. Afterwards the 0-ring seal 77 is disposed in the groove 76.

The positioning pin 7 with the head part 72 and the retaining member 73 is preferably made of plastics. So that it is possible to accommodate particularly large forces, the positioning pin 7 may have a preferably rectangular steel core 78, onto which the plastics material is sprayed.

Instead of the 0-ring seal 77, a disk seal may also be provided in the form of an annular disk, which tightly abuts the inner side of the through-bore 6.

Instead of the helical spr-Jng 74, a leaf or disk spring may also be provided as energy accumulator. A leaf spring 741 preferably has, in the manner evident from Figure 3, the form of at least one leaf element extending from the shaft 71 on the side of the head part 72 towards the side of the 35 retaining member 73 and protruding over the periphery of the shaft, which by its free end is resiliently supported on the facing side of the wall of the gear casing 1. At the 6 same time the leaf element 741 and the shaft 71 are preferably manufactured in one piece from a plastics material.

The force of the energy accumulator 74 or 74' has to be strong enough for the positioning pin 7 to be withdrawn from the bore 8 with the alignment of the bore 8 and the throughbore 6 and is preferably conveyed until the retaining member 73 abuts the gear casing 1, whereby the force with which the 0-ring seal 77 presses against the inner wall of the through-bore 6 is simultaneously overcome.

7 CLAIMS 1. A positioning pin for a transmission actuating mechanism, in particular a motor vehicle transmission, having a connecting part or bush rotatable and axially displaceable on a shaft of a gear casing for actuating the transmission, in which the connecting bush includes a bore adapted to be aligned with a through-bore of a wall of the gear casing, and in which, in the alignment position, the positioning pin is adapted to be pushed into said bore via said through-bore in order to fix the connecting bush in a predetermined position, wherein the positioning pin comprises an energy accumulator adapted to bias the pin to a position in which it can be withdrawn from said bore, a retaining member adapted to captively secure it in said through-bore, and a sealing device for sealing said throughbore.
2. A positioning pin according to Claim 1, wherein the energy accumulator is a helical spring surrounding the shaft of the positioning pin, which, when the positioning pin engages in the bore, is resiliently supported between a head part of the positioning pin disposed externally of the gear casing and the outside of that wall of the gear casing facing towards the head part.
3. A positioning pin according to Claim 1, wherein the energy accumulator is in the form of at least one leaf spring, which is disposed at a region of the shaft externally of the gear casing and the free end of which is resiliently supported on the outside of the gear casing.
4. A positioning pin according to any one of Claims 1 to 3, wherein the sealing device is in the form of an 0-ring seal disposed in a circumferential groove in the shaft of the positioning pin, which tightly abuts the inner face of through-bore in the position in which the positioning engages in said bore and in the position in which positioning pin is withdrawn from said bore.

said pin the 8
5. A positioning pin according to any one of Claims 1 to 4, wherein the retaining member is in the f orm. of a tongue part protruding over the outer periphery of the shaft at that side of the shaft of the positioning pin facing away from the head part in such a manner that the free end of the tongue part is supported on the edge region of the inside of said throughbore when the positioning pin is outwardly moved via the energy accumulator, or manually out of said through-bore.
6. A positioning pin according to any one of Claims 1 to 5, 10 wherein it is formed in one piece from a plastics material.
7. A positioning pin according to Claim 6, wherein a steel core is disposed in the shaft of the pin for strengthening purposes.
8. A positioning pin constructed and adapted for use substantially as hereinbefore described with reference to the accompanying drawings.
9. A transmission actuating mechanism having a positioning pin according to any one of the preceding Claims.