The present invention relates to a gearshift unit for a trans ^¬ mission of a vehicle, the gearshift unit comprising a releasa- ble blocking mechanism for blocking a shift lever from being moved to a shifting gate including the reverse gear, said blocking mechanism comprising a hollow shaft mounted around the shift lever to be slidable along a longitudinal direction of the shift lever, wherein an annular protrusion is projecting radially from the upper end of the hollow shaft, which annular protrusion may be grasped by a driver to lift the hollow shaft upwards towards a knob at the upper end of the shift lever to a release position in which the shift lever is free to be moved to the shifting gate including the reverse gear, wherein a helical spring is disposed within the hollow shaft and biasing it in downward direction to a blocking position in which a stop member of the hollow shaft blocks movement of the shift lever to the shifting gate including the reverse gear, wherein a spring holder fixed with respect to the shift lever supports one end of the spring which acts with its opposite end on the hollow shaft to urge it downwards.

A gearshift unit of this kind is disclosed in EP 0 225 211 Al . When a driver wants to change to the reverse gear he or she is grasping the annular protrusion with two fingers while the hand remains rested on the knob at the upper end of the shift lever. By pulling the annular protrusion upwards a stop member at the lower end of the hollow shaft is moved out of the way of a stationary blocking member such that the stop member may pass the blocking member and the shift lever may thus be moved to the shifting gate including the reverse gear. When the annular protrusion is lifted up to bring the hollow shaft to the release position, the upward movement is stopped by the annu ^¬ lar protrusion coming into abutment on a lower rim of the knob attached to the upper end of the shift lever. When the annular protrusion strikes on the lower rim of the knob this on the one hand creates noise and on the other hand is accompanied by an abrupt stop of the hollow shaft. These effects are even more serious because the upper part of hollow shaft has to be made of a material of sufficient hardness to provide suffi ^¬ cient rigidity. Therefore, a clicking noise is generated when the annular protrusion is pulled upwards such that the hollow shaft reaches its released position. Also, the sudden stop of the hollow shaft in the release position when it strikes the lower rim of the knob is experienced as an unpleasant actua ^¬ tion feeling by the driver. Also a finger or parts of the skin of a finger can be clamped between the upper surface of the annular protrusion of the hollow shaft and the lower rim of the knob when the hollow shaft is pulled upwards.

It is an object of the present invention to provide a gear shift unit such that a blocking mechanism for blocking a shift lever from being moved to a shifting gate including the reverse gear can be actuated with a minimum of noise generated. In addition, the blocking mechanism should be arranged such that it can be actuated providing a pleasant actuation feel ^¬ ing .

This object is achieved by a gear shift unit comprising the features of claim 1. Preferred embodiments of the invention are set out in the dependent claims.

According to the present invention the spring holder is provided with an elastic end stop projecting radially with re ^¬ spect to the shift lever axis and extending into an opening in the wall of the hollow shaft. This opening is arranged such that a lower edge of the opening contacts the end stop when the hollow shaft approaches the release position to thereby smoothly stop movement of the hollow shaft at the released po ^¬ sition.

In this manner the contact of the lower edge of the wall open ^¬ ing of the hollow shaft with the projecting end stop on the spring holder takes place at a location at a distance to the annular protrusion on the hollow shaft and the knob at the up ^¬ per end of the shaft. Already for this reason any noise gener ^¬ ated by this contact is less noticeable for the driver. In particular the opening in the wall of the hollow shaft can be located at a position such that it is surrounded by a gaiter in the assembled state of the gearshift unit which further re ^¬ duces any noise noticeable for the driver. In addition, the material of the spring holder and the dimensions and shape of the end stop can be chosen such that the end stop elastically deforms when the hollow shaft approaches its release a posi ^¬ tion, to thereby smoothly slow down the upward movement of the hollow shaft.

In a preferred embodiment the spring holder is a clip with two arched legs for embracing and engaging a sleeve fixed on the shift lever. The arched legs are connected by an apex portion, and the end stop is formed by a tongue extending from the apex portion. For mounting the spring holder the two arced legs are elastically spread part to allow them to be moved over an at ^¬ tachment sleeve on the shift lever, whereafter the two arched legs elastically return or snap back to fix the clip with re ^¬ spect to the shift lever.

In a preferred embodiment the spring holder comprises a flange portion projecting in radial direction with respect to the shift lever longitudinal axis. In this manner the flange por ^¬ tion provides a support surface for one end of the helical spring that is resting on the flange portion, wherein an inner extension of the clip is extending axially downwards and is extending into a gap between an end portion of the spring and the shift lever. In this manner the spring holder on the one hand provides a support surface for absorbing forces of the spring acting in the direction of the longitudinal axis of the shift lever and of the spring. In addition the clip extension extending into the gap between the helical spring and the shift lever further supports the spring against movements in a direction perpendicular to the longitudinal axis of the shift lever by arranging the clip extension to extend into the small gap between the outer surface of the shift lever and the wind ^¬ ings of the helical spring. This arrangement makes sure that the spring is held in place within the hollow shaft and pre ^¬ vents noise from being generated since the spring cannot be displaced such that it would hit the inner wall of the hollow shaft and create a rattling noise.

In a preferred embodiment the spring holder is integrally made of plastic material. Preferably the spring holder is made of thermoplastic polyurethane . Compared to other plastic materi ^¬ als thermoplastic polyurethanes can be provided with a rather low Shore A hardness. Therefore, the end stop may be arranged to be resilient. In this manner, the end stop can smoothly slow down the hollow shaft when it approaches its release po ^¬ sition.

In a preferred embodiment the hollow shaft is in axial direc ^¬ tion comprising an upper and a lower sleeve part connected to each other, wherein the upper and lower sleeve parts are made of different plastic materials. On the one hand, this two-part arrangement allows to assemble the hollow shaft on the shift lever after the spring holder has been fixed and the spring has been placed on the shift lever, and to connect the two parts to each other. On the other hand, the upper sleeve part can be made of a plastic material optimized with respect to structural rigidity, whereas the lower part can be made of a plastic material having a lower shore A hardness and higher elasticity. In this manner a better noise absorption may be achieved. During movements of the shift lever the lower sleeve part may hit the reverse wall of the base in which the shift lever is mounted. By selecting a softer material for the lower sleeve part the noise crated by such hits is reduced. For the upper sleeve part must be capable of absorbing higher loads. Therefore, this design with the hollow sleeve being assembled of separate upper and lower sleeve parts allows it to select suitable materials for the upper and lower sleeve parts inde ^¬ pendently from each other.

In a preferred embodiment the material of the upper sleeve part has a shore A hardness which is higher than the shore A hardness of the lower sleeve part.

In a preferred embodiment the upper sleeve part is made of polyoxymethylene and the lower sleeve part is made of thermo ^¬ plastic polyurethane .

In a preferred embodiment the upper sleeve part and the lower sleeve part are connected by a bayonet connection which is closed when the upper and lower sleeve part are assembled on the shift lever.

In a preferred embodiment one of the upper and lower sleeve parts comprises a projection and the other of the upper and lower sleeve parts comprises a complementary recess, wherein projection and recess are arranged to come into engagement when the bayonet connection reaches the closed state such that the bayonet connection can only be opened again by breking the projection. This is a safety feature because if the connection between the upper and lower sleeve part is opened up and the projections is broken away the shift lever cannot be moved to R. In a preferred embodiment the opening in the hollow shaft wall is formed in a lower end portion of the upper sleeve part. This implies that also the spring holder with its end stop projecting into the opening is located in the area of the low ^¬ er end portion of the upper sleeve part. This lower end por ^¬ tion of the upper sleeve part is sufficiently spaced apart from the upper end of the upper sleeve part so that it can be located in a portion of the shift lever which is covered by a gaiter. In this manner any noise created by the contact be ^¬ tween the end stop and the lower edge of the opening in the hollow shaft is further suppress by the surrounding gaiter.

The invention will now be described with reference to a pre ^¬ ferred embodiment shown in the accompanying drawings in which:

Fig. 1 shows a perspective view of a part of a shift lever as ^¬ sembly of a gearshift unit according to the invention, a hol ^¬ low shaft disposed on the shift lever;

Fig. 2 shows an exploded view of the parts of the hollow shaft, a spring holder and a spring;

Fig. 3 shows a perspective view of the spring holder; and

Fig. 4 shows cross-sectional views of the shift lever and the surrounding hollow shaft in the region of the spring holder and the spring, in a blocking position of the hollow shaft on the left hand side and in the upper release position of the hollow shaft on the shift lever on the right hand side.

With reference to Figs. 1 and 2 the gearshift unit shown has a shift lever 2 around which a hollow shaft 4 is arranged. The gear shift unit further comprises a base (not shown) including a bearing portion (not shown) for receiving a ball portion of the shift lever to mount the shift lever for pivotal movements in a shift direction and in a select direction perpendicular to the shift direction. The hollow shaft 4 is slidable along the longitudinal axis of the shift lever 2. The hollow shaft 4 is urged to a lower blocking position of the hollow shaft on the shift lever 2 by a helical spring 20 (see Fig. 2 and 4) . The helical spring 20 is disposed within the hollow shaft 4 and is acting between the shift lever 2 and the hollow shaft 4 to bias it in downward direction towards the blocking posi ^¬ tion. More precisely, the helical spring is abutting with its upper end against a spring holder 80 which in turn is in engagement with a mounting sleeve 92 (see Fig. 4) fixed on the shift lever. The lower end of the helical spring 20 is resting on a shoulder formed on the inner wall of the hollow shaft, as can be seen in Fig. 4.

The hollow shaft 4 is provided with an annular or circumferential protrusion 42 close to its upper end. A driver can place two fingers on opposite sides of the hollow shaft 4 below the annular protrusion 42 to grasp the hollow shaft 4 and pull it towards a knob (not shown) at the upper end of the shift lever to move the hollow shaft 4 to a release position in which a blocking member at the lower end of the hollow shaft 4 is lifted such that the blocking member can pass by a stationary stop member in the base of the gearshift unit to allow to shift to R.

The hollow shaft has a second annular protrusion 44 such that a finger can be placed in the valley between the two annular protrusions 42, 44.

As can be seen in Fig. 2 the hollow shaft is formed by two separate parts, namely an upper sleeve part 40 and a lower sleeve part 60. The upper sleeve part 40 is preferably made of a hard plastic material such as polyoxymethylene in order to provide the upper shaft part 40 with sufficient structural ri ^¬ gidity. The lower shaft part 60 is preferably made of a softer plastic material, such as a thermoplastic polyurethane . In this manner any contacts between the lower shaft part 60 and structures of the base in which the shift lever unit is mount ^¬ ed create less noise since the lower shaft part 60 is of a ra ^¬ ther soft plastic material. When the lower shaft part 60 has been pushed onto the shift lever, and the helical spring 20 and the spring holder 80 have been put into place, the upper shaft part 40 can be pushed onto the shift lever 2 and be con ^¬ nected to the lower shaft part 60 by a bayonet connection. Preferably, the upper shaft part 40 and the lower shaft part 60 include a couple of a projection and a recess which snap into engagement with each other when the bayonet connection reaches the closed state. The snap engagement of the projec ^¬ tion and the recess is such that the bayonet connection can only be open again by breaking away the projection. Therefore, it is not possible to disconnect the upper and lower shaft parts 40, 60 once there have been mounted and connected, and if this is nevertheless achieved by sufficient force the bro ^¬ ken projection ensures that the lower shaft part 60 is in a position such that shift lever movement to R is blocked.

The spring holder 80 is shown in more detail in Fig. 3. As can be seen the spring holder 80 is formed as a clip with two arched legs 84, 86 which are connected by an apex portion. The apex portion of the clip is provided with a radially extending end stop 82 which is extending from the apex portion of the clip in the opposite direction compared to the arched legs 84, 86. The arched legs 84, 86 and the apex portion of the clip have a certain radial extension with respect to the longitudi ^¬ nal axis of the shift lever, and thus form a flange portion projecting in radial direction to provide a support surface for the helical spring 20. The clip further comprises an upper projection 90 which is received in a recess of the upper shaft part 40 when the hollow shaft is in its lower blocking position, as can be seen on the left hand side in Fig. 4. Opposite to the upper projection 90 there is an inner extension 88 which is formed as a thin, arched wall and which is arranged to extend in downward direc ^¬ tion into a recess formed in the mounting sleeve 2 (see Fig. 4) fixed on the shift lever 2. In this manner the inner extension 88 extends downwardly into a gap between an upper end portion of the spring 20 and the mounting sleeve 90 fixed on a shift lever 2 (see Fig. 4) . In this manner the inner extension 88 removes free play of the spring 20 on the shift lever such that movements of the spring in a direction perpendicular to the longitudinal axis of the shift lever are prevented or at least reduced to a large extend. In this manner the creation of noise which could be created by rattling of the spring is prevented or largely reduced.

The spring holder 80 is preferably integrally made of plastic material. In particular, the spring holder is preferably made of a soft plastic material such as thermoplastic polyurethane. This provides also the end stop 82 with the characteristics of a soft plastic material, which is preferred as will be de ^¬ scribed further below.

The mounting sleeve 92 is provided around the shift lever 2 in a level region where the spring holder 80 is to be fixed (the mounting sleeve 92 is shown in Fig. 4 only) . The mounting sleeve 2 is provided with a recess for partially receiving the inner extension 88. By this engagement of the inner extension 88 in the recess in the mounting sleeve the spring holder 80 is engaged and fixed against movements in the direction of the longitudinal axis of the shift lever when the spring holder 80 is mounted on a mounting sleeve 92. The spring holder 80 is mounted by urging the arched legs 84, 86 apart such that the spring holder can be pushed onto the mounting sleeve 92. The arched legs 84, 86 elastically return when the spring holder 80 is pushed further onto the mounting sleeve 92 until the inner extension 88 is partially received in the recess of the mounting sleeve 92. The engagement of the inner extension 88 and the recess in the mounting sleeve 2 fixes the spring holder 80 in axial direction of the shift lever 2, and the arched legs 84, 86 fix the spring holder 80 in radial direction.

As can be seen in Figs. 1 and 2 the upper shaft part 40 is in its lower end region provided with an opening 48. As can be seen on the left hand side in Fig. 4 which shows the hollow shaft 40, 60 in the lower blocking position the opening 48 is arranged such that the end stop 82 of the spring holder 80 is close to the upper edge of the opening 48. When the hollow shaft is lifted up with respect to the shift lever 2 to the upper release position, which is shown on the right hand side in Fig. 4, the opening 48 has moved relative to the stationary spring holder 80 such that the end stop 82 of the spring hold ^¬ er 80 has come into abutment on a lower edge 50 of the opening 48. Therefore, when the hollow shaft is lifted up with respect to the shift lever to the release position the end stop 82 of the spring holder 80 comes into abutment with the lower edge 50 of the opening 48 in the last phase of the movement and stops the movement of the hollow shaft at the predetermined release position. As already mentioned above the spring holder 80 is preferably made of a rather soft plastic material such as a thermoplastic polyurethane . Therefore, end stop 82 does not cause an abrupt stop when the release position of the hol ^¬ low shaft is reached, but provides for a smooth stop, due to the soft material characteristics of end stop 82. When the driver, after the hollow shaft has been brought to the upper release position, releases the annular protrusion 42 again by removing his or her fingers, the helical spring 20 urges the hollow shaft back in downward direction to the lower locking position of the hollow shaft, as shown on the left hand side in Fig. 4.