Device for manually engaging a neutral gear, electric drive

Abstract

The invention relates to a device (1) for manually engaging a neutral gear in a transmission, comprising a selector fork (2), via which a first gear can be engaged in a first position, a second gear can be engaged in a second position, and the neutral gear can be engaged in an intermediate central position. The device according to the invention is characterized in that the selector fork (2) has two stops (3, 4), between which a control element (12) is movably arranged, wherein, in a first position, the control element (12) allows free movement of the selector fork (2) from the first position thereof into the second position thereof and back, wherein, in a second position, the control element (12) interacts with the stops (3, 4) in such a way that the selector fork (2) moves into the central position between the first and second positions, and wherein the control element (12) can be manually moved via an actuating device (5, 8, 9).

Description

[0001] Device for manually engaging neutral gear, electric drive

[0002] The invention relates to a device for manually engaging a neutral gear in a transmission of the type defined in more detail in the preamble of claim 1. The invention also relates to an electric drive for a motor vehicle with such a device.

[0003] If a vehicle breaks down, it may be necessary to tow it, for example, to the nearest garage for repairs. With automatic vehicles, and especially electric vehicles, a gear typically remains engaged when the vehicle stops. When the vehicle, particularly an electric vehicle, is towed, the wheels, transmission, and electric motor continue to move. This can lead to damage, particularly due to the often-lacking lubrication and cooling in this situation, and potentially very high speeds within the electric motor and / or transmission during towing.

[0004] For this reason, it is generally known to provide devices to be able to manually engage a neutral gear in such a situation.

[0005] In this context, reference can be made to US 6,443,276 B2, which moves a pin-shaped actuator via a cable pull in order to engage neutral gear by moving a shift fork.

[0006] For further prior art, reference can also be made to US 2022 / 0243813 A1, which describes a similar actuator in connection with engaging or releasing a parking brake. The object of the present invention is to provide an improved design solution for a device for manually engaging neutral in a transmission according to the preamble of claim 1. According to the invention, this object is achieved by a device with the features in claim 1, and in particular in the characterizing part of claim 1. Advantageous embodiments and further developments are described in the dependent claims. Claim 8 also describes an electric drive with such a transmission and such a device.

[0007] The device according to the invention serves for manually engaging a neutral gear in a transmission. This transmission comprises at least one shift fork, via which a first gear is engaged in a first position, a second gear in a second position, and neutral in an intermediate middle position.

[0008] The inventive design provides that the shift fork has two stops between which a control element is movably arranged. In a first position, the control element allows free movement of the shift fork from its first to its second position and back. In this first position of the control element, the user can freely select between first gear, second gear, and neutral. In this first position, the stops do not strike the control element or only come into contact with it to the extent that the shift fork can assume the aforementioned positions.

[0009] Furthermore, in a second position, the control element interacts with the stops in such a way that the shift fork moves to the center position between the first and second positions, thus engaging neutral. The control element can be operated manually or manually triggered via an actuating device.

[0010] The design allows for free movement of the shift fork in the first position of the control element, thus enabling unrestricted use of the transmission. In an emergency situation, for example, when the vehicle needs to be towed and neutral gear must be engaged, the control element can be manually moved from its first position to its second position. This movement engages with the stops of the shift fork, shifting it into its neutral position.

[0011] For example, two stops could be provided on two sections of the shift fork pointing towards the respective end positions of its movement. The control element lies between these stops and could, for instance, be designed as a tapered wedge. The shift fork can then be moved into both positions as long as only the tip of the wedge lies between the two stops, since this tip is correspondingly narrower than the movement of the shift fork and thus the stops required for shifting. If this wedge, acting as the control element, is now moved from one position to a second position, it will interact, regardless of the current shift position, first with one, then with the other, or with both of the stops, in such a way that the shift fork is centered in its neutral position, thus engaging neutral.

[0012] This theoretically conceivable functionality of a linearly moving control element is correspondingly complex to implement in practice, since linear movement often requires a series of bearings, a corresponding mounting, and the like. According to a particularly advantageous embodiment of the device according to the invention, the movement of the control element from its first to its second position can therefore be achieved by a rotation. According to a further advantageous embodiment, the angle of rotation can be limited by at least one stop surface to prevent rotation beyond a predetermined position.

[0013] The control element itself can be essentially S-shaped or mirrored in this respect, in order to ensure the free movement of the two stops in a position where the S is perpendicular to the connecting line between them, and to center them by rotating the S into a horizontal position with respect to the connecting lines of the stops.

[0014] A further highly advantageous embodiment of the device according to the invention can also provide that the actuating device is designed as a cable pull which is attached off-center to a lever element in order to rotate it, the lever element being rotationally coupled to the control element. A rotationally fixed connection is understood to be a connection in which both components rotate at the same angular velocity. For example, the control element can be arranged on a shaft which interacts with the lever element via a flat or toothing, while the control element itself is formed integrally with the shaft or welded to it. The cable pull can have a loop at its free end for manual actuation. This loop can, for example, be provided with a colored covering so that the position of the control element is easily recognizable visually based on the cable pull.

[0015] A hook can be provided to secure the cable in its fully extended position; preferably, the loop can be attached to this hook. The hook is spring-loaded to release the cable from its fixation once a predetermined tensile force is applied. This ensures that even if a user forgets to remove the loop from the hook before starting the vehicle, the control element is still released upon starting, thus restoring normal operation.

[0016] Another very advantageous embodiment can also provide for a return spring to interact, at least indirectly, with the control element to return it to its first position. The design is then such that, for example, a short pull on the cable moves the control element to its second position, thereby shifting the shift fork so that neutral is engaged. If the transmission is designed such that this neutral position cannot be disengaged without further force being applied to the control fork, then the return spring allows the control element to return to its original first position when the cable is released, i.e., at the end of the manual cable actuation. This means that all available gears can be engaged again as needed without any further intervention. The return spring can preferably be designed as a torsion spring or a coil spring.

[0017] In principle, this design can be implemented in various transmissions. However, the design is particularly advantageous in an electric drive, where this electric drive for a motor vehicle has a transmission comprising a shift fork. In a first position, a first gear is engaged, in a second position a second gear, and in an intermediate middle position a neutral gear. Such an electric drive can now be equipped with the device according to the invention to enable simple and efficient towing of such an electric vehicle. This is achieved by briefly manually moving the control element to its second position to engage neutral in the transmission, thereby allowing the vehicle to be towed without the transmission and electric motors moving with the rotating wheels.

[0018] Further advantageous embodiments of the device according to the invention also result from the exemplary embodiment, which is described in more detail below with reference to the figures.

[0019] This shows:

[0020] Fig. 1 shows a schematic cross-section through a possible embodiment of the device according to the invention;

[0021] Fig. 2 shows an exemplary lever element from the structure according to Fig. 1;

[0022] Fig. 3 shows an exemplary stop element with stop surfaces for limiting the angle of rotation from the setup according to Fig. 1;

[0023] Fig. 4 shows the control element and a relevant section of the switching fork in three possible switching positions during regular operation;

[0024] Fig. 5 shows a representation analogous to that in Fig. 4 when manually engaging neutral;

[0025] Fig. 6 shows the end of the cable opposite the lever element with a spring-loaded hook for fixing it; and

[0026] Fig. 7 shows a rear view of the spring-loaded hook.

[0027] Figure 1 shows a schematic cross-section of a device 1 according to the invention. In the lower part of Figure 1, a section of a shift fork 2 of a transmission (not shown in its entirety) is visible. This section comprises a substantially cuboid element, which can be an integral part of the shift fork 2, usually manufactured by a casting process. This cuboid element of the shift fork 2 carries two stops, designated 3 and 4, which are designed here as pins and can, for example, be pressed into bores in the shift fork 2.

[0028] A cable or Bowden cable 5, which is received in an abutment 6 of a bracket 7, serves to actuate the device 1. Its cable 8 runs to a lever element 9 and is received therein in a manner known per se. The lever element 9, together with the cable 8, can be seen again in Figure 2. The cable runs along the outer circumference in a groove provided for this purpose and can, for example, be received in a bore 10 of the lever element 9 by means of a nipple, as is common on Bowden cables 5 at the end of the cable 8. Depending on the design of the lever element 9, which is shown here purely as an example of a circular segment, the lever travel can be varied by its specific shape over the path of movement, in order to, for example, compensate for increasing forces opposing the movement by means of an increasingly longer lever, or similar.

[0029] The lever element 9 is non-rotatably connected to a shaft 11, for example via a positive-locking connection through a toothed connection, a surface on the shaft 11 with a corresponding design of the central opening of the lever element 9, or the like. The shaft 11 is rotatably mounted in the holder 7. At the other end of this shaft 11, a control element 12 is non-rotatably connected to it, for example, integrally formed with the shaft 11 or welded to it. This control element 12 lies between the two stops 3, 4 of the shift fork 2 and can be rotated by actuating the Bowden cable 5 via the lever element 9, as will be discussed in more detail later.

[0030] A return spring 13 is also arranged between the bracket 7 and the control element 12. This spring is connected to the bracket 7 on one side and the control element 12 on the other such that it returns the control element 12 to the first position shown and described in Figure 3 when no force acts on the cable 8 of the Bowden cable 5, or when only a force less than the return force of this return spring 13 acts on it. The return spring 13 can be designed as a torsion spring, as shown here. Alternatively, a coil spring would also be conceivable, which would allow for a flatter design in the vertical direction. In Figure 1, stop surfaces 14 and a stop element 15 are also visible between the lever element 9 and the bracket 7. Figure 3 shows a schematic top view of these.The stop element 15 is positively locked and rotationally fixed to the shaft 11 and has sections projecting beyond its circular outer contour, which, in the position shown in Figure 3, bear against stop surfaces 14. In this position, the lever element 9 should be fully deflected by manual actuation, so that the control element 12 has reached its second position, described in more detail in Figure 5. The stop surfaces 14 and the stop element 15 thus help to prevent the device 1 from being over-rotated during manual actuation.

[0031] In principle, other options for manually operating the device 1 would be conceivable besides the Bowden cable 5. The Bowden cable 5 has the decisive advantage that it can be very easily guided from one position of the device 1 to a position that is readily accessible for manual operation. The end of the Bowden cable 5, or rather its rope 8 at the end facing away from the device 1, can then simply be bent into a loop 17 (see Figure 6) and crimped to itself, thus enabling very simple and efficient manual operation.

[0032] The operating principle of the control element 12 is essentially derived from the illustrations in Figures 4 and 5. These figures each show a section of the shift fork 2 with the two stops 3 and 4. The view is essentially a top view of the illustration in Figure 1, excluding all elements located above the control element 12. The control element 12 is shown together with its axis of rotation A. In the three illustrations of Figure 4, it is in its first position, in which the shift fork 2 can be freely actuated. The shift fork 2 is moved according to the double arrow shown in the illustrations of Figure 4. The illustration in Figure 4a) shows first gear and thus the first position of the shift fork 2. The illustration in Figure 4c) shows second gear and thus the second position of the shift fork 2.This second position can be assumed without the stops 3 and 4 touching the control element 12. Figure 4b) then shows the intermediate central position of the shift fork 2, in which the transmission (not shown here) is in neutral. In normal operation, the control element 12 is therefore in this first position, so that first gear, second gear, and neutral can be easily selected using known means for actuating the shift fork 2.

[0033] If a vehicle equipped with device 1, for example an electric vehicle, breaks down and needs to be towed, it is important that neutral gear can be engaged manually. To do this, the cable 8 of the Bowden cable 5 is pulled, and the lever element 9 shown in Figure 1 rotates the control element 12, which is rigidly connected to it, clockwise into the position shown in Figure 5. In the embodiment shown here, the control element 12 is essentially S-shaped, or a mirror image of it. Its shape could also be described as two semicircles offset from each other at their straight edges by slightly less than the diameter of the circles. This creates the necessary clearance for the regular actuation of the shift fork 2 according to its positions shown in Figure 4.When the device 1 is manually actuated, the control element 12 is rotated and its control surfaces 16, formed by the arcs of the two semicircles, engage with the two stops 3 and 4, regardless of whether first or second gear is engaged. Thus, the manual actuation always moves the shift fork 2 to its neutral position when the control element 12 reaches its second position. The desired manual engagement of neutral gear has now been achieved. If this neutral gear is retained automatically in the transmission after engagement, the control element 12 can be returned to its first position by releasing the cable 8 of the Bowden cable 5 and the action of the return spring 13, so that the full functionality of the transmission is restored.If this is not the case on the gearbox side, the control element 12 could also remain in the second position shown in Figure 5 until the repair is completed and would then have to be manually reset accordingly.

[0034] Figure 6 shows the end of the cable 5 opposite the end shown in Figure 1. The cable 8 forms the loop 17 mentioned above. This loop serves for manual operation of the mechanism and can be covered with a colored coating 20, so that the status of the control element 12 can be easily identified visually by the Bowden cable 5. A hook 18 is also provided for attaching and securing the loop 17. This hook 18 protrudes through an opening 12 in a sheet metal component 22. The hook 18 is spring-loaded and can, for example, be designed as the central part of a double torsion spring 19, as can be seen in the rear view of Figure 7. The double torsion spring 19 sits on a bolt 23 and is supported against the rear of the sheet metal component 22.

[0035] The spring force of the spring-loaded hook 18 or the double torsion spring 19 is set such that it releases the loop 17 and thus ultimately the control element 12 when a predetermined tensile force is exceeded. If a person using the device 1 forgets to remove the loop 17 from the hook 18, this ensures that the control element 12 is released when the vehicle is started. This restores the normal function of the device 1.

Claims

Patent claims 1. Device (1) for manually engaging neutral in a transmission, comprising a shift fork (2) via which a first gear can be engaged in a first position, a second gear in a second position, and neutral in an intermediate intermediate position, characterized in that the shift fork (2) has two stops (3, 4) between which a control element (12) is movably arranged, wherein the control element (12) in a first position allows free movement of the shift fork (2) from its first to its second position and back, wherein the control element (12) in a second position interacts with the stops (3, 4) such that the shift fork (2) moves into the intermediate position between the first and second positions, and wherein the control element (12) is manually movable via an actuating device (5, 8, 9).

2. Device (1) according to claim 1 , characterized in that the stops (3, 4) are designed as pins.

3. Device (1) according to claim 1 or 2, characterized in that the movement of the control element (12) from its first position to its second position is effected by a rotation.

4. Device (1) according to claim 3, characterized in that the angle of rotation is limited by at least one stop surface (14).

5. Device (1) according to claim 3 or 4, characterized in that the actuating device comprises a cable pull (5, 8) which engages an off-center lever element (9) in order to rotate it, wherein the lever element (9) is coupled to the control element (12) in a rotationally fixed manner.

6. Device (1) according to claim 5, characterized in that a hook (18) is provided for fixing the cable pull (5,8) in its fully extended position, wherein the hook (18) is spring-loaded in order to release the cable pull (5,8) from its fixation from a predetermined tensile force.

7. Device (1) according to one of claims 1 to 6, characterized in that a return spring (13) cooperates at least indirectly with the control element (12) to return it to its first position.

8. Device (1) according to one of claims 1 to 7, characterized in that the control element (12) is S-shaped or mirrored thereto.

9. Electric drive for a motor vehicle with a transmission comprising a shift fork (2) via which a first gear can be engaged in a first position, a second gear in a second position and a neutral gear in an intermediate intermediate position, and with a device (1) according to one of claims 1 to 8.

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