GB2027498A

GB2027498A - A synchromesh device for a transmission

Info

Publication number: GB2027498A
Application number: GB7923058A
Authority: GB
Original assignee: Nissan Motor Co Ltd
Current assignee: Nissan Motor Co Ltd
Priority date: 1978-07-03
Filing date: 1979-07-03
Publication date: 1980-02-20
Also published as: GB2027498B; DE2926617A1; JPS558224U; JPS5825143Y2

Abstract

A synchromesh device for a transmission for use in a vehicle comprises a coupling sleeve (7) and a baulk-ring (10, 11) arranged at each side of the coupling sleeve (7), the baulk-rings (10, 11) being moved together in response to an axial movement of the coupling sleeve (7) to bring a frusto-conical surface of either one of the baulk- rings into contact with a frusto- conical surface of a change gear (2, 3) by being interconnected by pins (14). The pins (14) prevent insert keys (8) from coming out of the baulk-rings (10, 11) and coupling sleeve (7) and prevent noise and wear resulting from binding of the baulk-rings (10, 11). <IMAGE>

Description

SPECIFICATION A synchromesh device for a transmission The present invention relates to a synchromesh device for a transmission for use in vehicles and the iike.

Warner type synchromesh devices have been generally used for transmission for vehicles. The device of this type has a disadvantage in that insert keys often move out of notches of baulk-rings and further out of a coupling sleeve, when the baulk-rings have worn, or the coupling sleeve moves beyond a predetermined stroke, or inclines or skews during the shifting movement.

In the case of using a high viscosity oil in the device or in a cold season, moreover, the baulk-ring which is not in engagement with the coupling sleeve during operation is moved with the oil and binds therearound, thereby increasing wear of threads of the frusto-conical surface and a generating noise resulting from the excessive clearance caused by the wear.

During the synchronizing operation, further more, the baulk-ring which is not in engagement with the coupling sleeve is free in its axial direction without being retained by any axial force, so that the baulk-ring is moved with the oil and thus the frusto-conical surface of the baulk-ring always slides on the frustoconical surface of an associated change gear with resulting increased wear.

It is an object of the invention to provide an improved synchromesh device for a transmission which eliminates the disadvantages of the prior art devices.

It is aother object of the invention to provide a synchromesh device for a transmission for use in vehicles, which can prevent insert keys from coming out of the baulk-rings and coupling sleeve and prevent noise and wear which would otherwise occur.

The invention consists in a synchromesh device for a transmission, including a coupling sleeve and a baulk-ring arranged at each side of said coupling sleeve, either of said baulkrings being urged in response to an axial shifting movement of said coupling sleeve in either direction to bring a frusto-conical surface of said baulk-ring into contact with a frusto-conical surface of one of change gears for a synchromesh operation, wherein a plurality of connection means integrally connect the pair of baulk-rings.

The invention will be more fully understood by referring to the following detailed specification and claims taking in connection with the accompanying drawings.

Figure 1 is a longitudinal sectional view of one embodiment of the synchromesh device according to the invention Figure 2 is a partial sectional view of another embodiment of the synchromesh device according to the invention; Figure 3 is a partial sectional view of further embodiment of the synchromesh device according to the invention; and Figure 4 is a longitudinal sectional view of one example of synchromesh devices of the prior art.

Referring to Fig. 1 illustrating one embodiment of the invention, a main shaft 1 rotatably supports thereon forward and reverse change gears 2 and 3 by bearings 4 and 5 and comprises a synchronizing hub 6 fixed onto the main shaft 1 by means of spline grooves.

The synchronizing hub 6 has formed around its outer surface spline grooves through which a coupling sleeve 7 is axially slidably mounted on the synchronizing hub 6.

The outer surface of the synchronizing hub 6 includes notches within which are recieved insert keys 8 adapted to be urged radially outwardly by means of spread springs 9 into grooves formed in an inner surface of the coupling sleeve 7 intermediate the ends thereof.

Baulk-rings 10 and 11 are respectively formed in their radially inner surface with frusto-conical surfaces which face respective frusto-conical surfaces formed at the sides of clutch gears 1 2 and 1 3 integrally formed with the forward and reverse change gears 2 and 3. The baulk-rings 10 and 11 are also formed in their outer surfaces on the sides opposite to each other with notches in which are located the insert keys 8.

In this embodiment, the baulk-rings 10 and 11 are integrally connected to each other by means of connection pins 1 4 which are arranged in parallel with the main shaft 1 and with their ends press fitted in the baulk-rings.

Preferably, there are three connection pins which are circumferentially spaced with their intermediate portions extending through the through apertures 1 5 formed in the synchronizing hub 6.

With this arrangement, when the coupling sleeve 7 is moved for example toward the forward change gear 2 by means of a shift fork (not shown), the insert keys 8 are moved together with the coupling sleeve 7 with the aid of the spread springs 9, so that the end faces of the insert keys 8 urged the frustoconical surface of the baulk-ring 10 into contact with the frusto-conical surface of the forward change gear 2. At the same time, the baulk-ring 11 is also moved in the same direction with the baulk-ring 10 connected by the connection pins 14, whereby the frustoconical surface of the baulk-ring 11 is positively separated from the frusto-conical surface of the reverse change gear 3.When the rotational speed of the coupling sleeve 7 becomes equal to that of the forward change gear 2 in the manner according to the well known synchronizing function, the coupling sleeve 7 pushes the insert keys 8 inwardly and engages the splines in the outer surface of the baulk-ring 10 and the clutch gear 12, thereby transmitting the driving power from the forward change gear 2 driven by a power source (not shown) through the coupling sleeve 7 and the synchronizing hub 6 to the main shaft 1.

In this case, the baulk-ring 11 is moved together with the baulk-ring 10 in unison keeping the distance therebetween constant.

Accordingly, the insert key 8 arranged therebetween never moves out of the baulk-rings.

Once the coupling sleeve 7 has engaged the baulk-ring 10, the other baulk-ring 11 never binds so that any wearing and noise resulting from the binding action of the baulk-ring is prevented.

The device may be assembled in the following sequence.

(i) The forward change gear 2 with the bearing 4 is mounted onto the main shaft 1.

(ii) The baulk-ring 10 with the connection pins 14 fixed thereto is fitted on the for ward change gear 2.

(iii) The synchronizing hub 6, spread springs 9, insert keys 8 and coupling sleeve 7 are arranged on the main shaft 1.

(iv) The baulk-ring 11 is inserted in position such that the other ends of the connection pins are press fitted in the baulk-ring 11.

(v) The reverse change gear 3 together with the bearing 5 is mounted onto the main shaft 1.

Fig. 2 illustrates another embodiment of the device according to the invention, which is similar to the device shown in Fig. 1 with the exception of a locking device for controlling the positions of the baulk-rings 10 and 11 in other than their synchronizing the positions.

In this embodiment, piate-iike connection pins 14 connecting the baulk-rings 10 and 11 as a unit are deformed at their mid portions to form recesses 1 6. The synchronizing hub 6 is formed with radial bores 1 7 crossing the through apertures 1 5 described in Fig. 1, within which apertures 1 7 are received springs 18 and location balls 19. In this manner, the balls 1 9 are urged against the connection pins 14 by means of the springs 18 so that the location balls 1 9 are urged in the engaging recesses 1 6 of the connection pins 14 when the baulk-rings 10 and 11 are in the neutral position.In other words, an external force more than a determined value is required to release the engagement of the location balls 1 9 with the recesses 1 6. In order to effect the synchronization, the baulkrings 10 and 11 connected by the connection pins are bodily urged by the insert keys 8 to release the engagement of the location balls from the recesses. After the completion of the synchronization, the insert keys 8 come out of grooves of the coupling sleeve 7 so that no external force is exerted on the baulk-rings which thus stop in the required position.However, when the coupling sleeve 7 is returned to the neutral position, the insert keys 8 are again engaged in the grooves of the coupling sleeve 7, so that the baulk-rings 10 and 11 are urged in the reverse direction to return the location balls 1 9 in to the recesses 1 6.

For the purpose of synchronization, therefore, when the baulk-ring 10 is pushed with the end surfaces of the insert keys 8 to move together with the coupling sleeve 7 to overcome the restraining force of the balls and recesses, the balls are forced into the bores 1 7 to relase the location balls 1 9 from the recesses 16, so that the baulk-rings 10 and 11 and the connection pins 14 are moved in unison to bring the frusto-conical surface of the baulk-ring 10 into contact with the frustoconical surface of the forward change gear 2 for carrying out the synchronizing operation.

After the completion of the synchronization, when the coupling sleeve 7 urges the insert keys 8 inwardly to bring it into the engagement with the splines in the outer peripheries of the baulk-ring 10 and the clutch gear 12, no axial force acts on the baulk-ring 10, so that they stop in their required positions. After the completion of the synchronization, in this manner the frusto-conical surface of the bauikring 11 is not in contact with the frustoconical surface of the reverse change gear 3, thereby remarkably reducing wear of the baulk-ring 11. When the coupling sleeve 7 is moved toward the reverse change gear 3, the same operation as that described above is of course effected in the changed relation between the baulk-rings 10 and 11.

Referring to Fig. 3, the connection pins 14 are in the form of rods. In this case, each rod is formed in its mid portion with a reduced diameter portion which forms a recess 1 6 as in the above embodiment shown in Fig. 2.

Fig. 4 illustrates a Warner type synchromesh mechanism generally hitherto used for vehicle transmissions. In such a conventional type, insert keys 31 are apt to move out of notches of baulk-rings 32 and 33 and further out of a coupling sleeve 34, when the baulkrings have worn or the coupling sleeve moved beyond a predetermined stroke or skewed in shifting movement as shown in Fig. 4.

As can be seen from the above explanation, the device according to the invention can prevent the insert keys from coming out of the baulk-rings and coupling sleeve and prevent wear and excessive noise by restraining the binding of the baulk-rings.

Claims

1. A synchromesh device for a transmission, inciuding a coupling sleeve and a baulkring arranged at each side of said coupling sleeve, either of said baulk-rings being urged in response to an axial shifting movement of said coupling sleeve in either direction to bring a frusto-conical surface of said baulkring into contact with a frusto-conical surface of one of change gears for a synchromesh operation, wherein a plurality of connection means integrally connect the pair of baulkrings.

2. A device as set forth in claim 1, wherein said connection means are rods whose ends are press fitted in said baulk-rings.

3. A device as set forth in claim 2, wherein each said connection means is provided in its substantially mid portion with engaging means with which is engaged location means with the aid of a spring force acting perpendicular to an axial direction of said connection means to restrain said baulk-rings in a neutral position.

4. A device as set forth in claim 3, wherein each said connection means is plate-like which is formed in its mid portion with a recess as said engaging means, and said location means is a ball.

5. A device as set forth in claim 3, wherein each said connection means is a rod which is formed in its mid portion with a reduced diameter portion as said engaging means, and said location means is a ball.

6. A synchromesh device substantially as described with reference to, and as illustrated in, Fig. 1, or Fig. 2, or Fig. 3 of the accompanying drawings.