WO2008110555A2 - Electrical shifting device for a motor vehicle - Google Patents

Abstract

An electrical shifting device for a motor vehicle comprises at least one shift lever (1) which is received so as to pivot about at least one axis (3a), and at least one locking device which can activate or inactivate a shift stop for the shift lever (1). The shifting device according to the invention is characterized in that the locking device comprises hydraulically active elements.

Description

 Electrical switching device for a motor vehicle

The invention relates to an electrical switching device for a motor vehicle, with a lever mounted pivotably about at least one axis and with at least one locking device which can put a shift stop for the shift lever in or out.

Such switching devices are used in motor vehicles that are equipped with an automated manual transmission. In this case, the actual switching operation is performed electro-hydraulically or by electric motor, while the respective switching request of the driver is detected electrically or electronically. The driver are in such an automated transmission, the electric switching device with a shift lever and possibly additional, arranged approximately on the steering wheel rocker switches for upshifting and downshifting available.

The lever of such a switching device can be made multi-stable or monostable, that is, he can either be adjustable in several fixed positions or he has, similar to a joystick only a stable rest position in which the lever from several unstable positions repeatedly falls back.

In both cases, it is desirable or even necessary, depending on the currently selected switching state, each exclude certain switching states of the next selection. It is advantageous, for example, to display a linear chain of possible switching states when the choices in a switching direction are exhausted.

Since in general not only the detection but also the processing of the respective switching states takes place by electrical or electronic means, In general, the exclusion of certain switching options can and will be carried out by the underlying switching logic. However, it is advantageous for ergonomic reasons, if the operator of the switching device also receives an immediate haptic feedback on currently not selectable switching functions. Such feedback receives the driver of a motor vehicle, in particular via locks or stops, which interact with the shift lever.

From EP 1 464 875 A2 a switching device is known, which has a device which can override a switching stop, so that the switching lever is pivotable beyond the switching position defined by this switching stop. For this purpose, EP 1 464 875 A2 discloses a relatively complex built-up rocker arm arrangement, which is actuated by an electromagnetic drive. However, such a drive can cause disturbing noises and a significant amount of heat during its operation.

The electrical switching device according to the present invention has the advantage over this prior art device, particularly low noise and without significant self-heating to limit or release the actuating travel of a shift lever. This is inventively achieved in that the device comprises hydraulically acting means.

In particular, the device comprises a cylinder filled with an incompressible liquid, in which a piston is received axially displaceable, wherein the switching stop is set by fixing the piston in a position in force. To return the piston to its initial position, a helical compression spring is arranged between the shift lever facing away from the bottom wall of the cylinder and the piston, which presses the piston with its spring force against the shift lever facing the top wall of the cylinder.

A very robust construction of the locking device with simple mechanical elements succeeds in that the incompressible liquid present in the cylinder is a magnetorheological fluid.

In a first embodiment of the barrier device with magnetorheological fluid, the bottom wall of the cylinder is provided with an opening and this connected to a pipeline which opens into a reservoir. At one point of the pipeline while an electromagnet is arranged so that the pipeline passes through an air gap in the yoke

In a second particularly preferred embodiment of the barrier device with magnetorheological fluid, a gap is formed between the radial outer contour of the piston and the inner wall of the cylinder through which the fluid in the axial direction of the cylinder from one side of the piston to the other and back flow. The cylinder is surrounded here by an electrical conductor coil, which is electrically energized to generate a magnetic field in the interior of the cylinder.

A preferred application of an electrical switching device is to block switching paths of a monostable or multi-stable gear selector switch depending on the already inserted gear. Further advantageous embodiments and further developments of the switching device according to the invention will be explained with reference to the drawing.

Show it:

1 shows a switching device according to the invention with hydraulic elements for a magnetorheological fluid according to a first embodiment,

Figure 2 one of the hydraulic elements of Fig. 1 as a detail

3 shows a hydraulic element according to an alternative embodiment for use in the switching device of FIG. 1 as a partially sectioned three-dimensional view and in cross section

The shift lever 1 of the electrical switching device is mounted in a universal joint 2 about two mutually perpendicular axes 3a and 3b pivotally. In order to realize the actuating forces and locking positions of the shift lever 1, it is provided at its lower end with a spring-loaded locking pin 8, which is guided in a three-dimensional latching cam 9.

In order to selectively limit the deflection of the shift lever at a pivoting about the axes 3a and 3b in one direction, are provided in each of these directions as parallel to the deflection of the shift lever 1 movable plunger 6 formed limiting elements.

The plungers 6 are each connected to a piston 5, which is axially displaceable in a cylinder 4 filled with an incompressible liquid 10 is included. A helical compression spring 7 is arranged in the cylinder 4 between the shift lever 1 facing away from the bottom wall 4a and the piston 5 and pushes the piston 5 with its spring force against the shift lever 1 facing top wall 4b of the cylinder 4. The piston 5 connected to the plunger 6 is located itself with its front side in the immediate vicinity of the shift lever 1, so that it already comes to a leading in the direction of the plunger 6 pivoting movement after a very short path to this.

The bottom walls 4a of the cylinder 4 are each provided with an opening and connected to pipes 11, which open at their other ends in a common reservoir, not shown here.

In the case of the incompressible liquid present in the cylinders 4 as well as in the pipelines 11 and the reservoir, in the exemplary embodiment shown, this is a so-called magnetorheological fluid.

Magnetorheological or electrorheological fluids are liquids in which the rheological properties, ie their fluidity or viscosity, are steplessly controllable by an applied external magnetic or electric field. As a rule, these liquids are suspensions, ie solid particles suspended in a carrier medium which can be polarized via the applied magnetic or electric field. By a sufficiently strong magnetic or electric field, such a strong local solidification of the magnetorheological or electrorheological fluid can be achieved within a few milliseconds that it has a practically solid character and is no longer flowable. By using magnetorheological or electrorheological fluids, it is possible to execute hydraulic systems without moving parts or to significantly reduce the number of moving parts. The magnetorheological fluid used in this embodiment can of course also be replaced by an electrorheological fluid when the hydraulic elements are adapted accordingly.

At each pipe 11, a solenoid 12 is arranged at one point so that the pipe 11 passes through the air gap in the yoke 13. This is shown in detail in FIG. 2. If the electromagnet 12 is turned on by energizing its coil 14, then the magnetic field penetrates the pipeline 11 at this point and solidifies the magnetorheological fluid 10 there locally so strongly that a flow through the cross section of the pipeline 11 is no longer possible. The solenoid 12 thus forms a hydraulic valve in cooperation with the magnetorheological fluid 10.

When all the electromagnets 12 are turned off, the liquid 10 between the cylinders 4 and the common reservoir can flow freely. If the shift lever 1 is pivoted in one direction, it presses the plunger 6 opposite in this direction against the force of the helical spring 7. The piston 5 displaces the liquid 10 from the cylinder 4 and this flows through the pipe 11 into the reservoir.

The movement of the shift lever 1 counteracting force is composed of the by the interaction of the spring-loaded locking bolt 8 and the associated three-dimensional locking cam 9 and the force of the coil spring 7 together, wherein the force of the coil spring 7 is only dimensioned so strong that this one safe provision of the piston 5 is ensured in its end position on the top wall 4b of the cylinder 4.

The provided for resetting the piston 5 in its end position helical compression springs 7 can possibly even be saved by a certain pressure is exerted on the liquid 10 in the reservoir, which then causes a return of the piston 5 via the liquid.

The provision of the shift lever 1 in its center position is carried out either after elimination of the deflecting actuation force by the latching cam 9 and the locking pin 8, if it is a tactile actuation, or by applying a counteracted in the opposite direction of the original operation counteracting force, if it is a latching operation is.

If the pivoting of the shift lever 1 to be blocked in a certain direction, this is done by the fact that in this direction the shift lever 1 opposite plunger 6 is prevented from retreating. For this purpose, the this plunger 6 via piston 5, cylinder 4 and pipe 11 associated electromagnet 12 is energized so that the magnetorheological fluid 10 in the region of the air gap of the yoke 13 of the electromagnet 12 solidifies so strong that a flow through the cross section of the pipe 11th is no longer possible. Since the liquid 10 is incompressible, the piston 5 can no longer displace it out of the cylinder 4, so that the piston 5 connected to the plunger 6 the

Blocked movement of the shift lever 1 in this direction and thus forms a switching stop for the switching device.

If the magnetic field of the electromagnet 12 is turned off by interrupting the energization of the coil 14, so is the magnetorheological Fluid 10 immediately flow again, and the lock for the shift lever 1 is canceled.

The hydraulically acting locking device shown here with a magnetorheological fluid 10 is of course also feasible with other Hydaulikflüssigkeiten, in which case would be used instead of the electromagnet 12 electromechanically acting valves.

An alternative embodiment of the cylinders 4 using a magnetorheological fluid 10 is shown in FIG. The cylinder 4 shown here can replace the cylinder shown in FIGS. 1 and 2 directly.

The particular advantage of the cylinder 4 shown in Fig. 3 is that it can be dispensed with piping and a reservoir, since this cylinder 4 is a closed system in which the liquid 10 within the cylinder 4 by overflow from a Side of the piston 5 is shifted to the other.

The only opening of the cylinder 4 is in its top wall 4b, through which the plunger 6 connected to the piston 5 projects outwardly. In contrast to the cylinder 4 in Fig. 2 in which the piston 5 rests sealingly with its radial extent on the inner wall of the cylinder 4, a gap 15 is formed here between the radial outer contour of the piston 5 and the inner wall of the cylinder 4. If a force is exerted in the direction indicated by the arrow in FIG. 3 on the plunger 6, it is moved against the force of the helical compression spring 7. The liquid 10 located between the piston 5 and the bottom wall 4a of the cylinder 4 is thereby introduced into the space between the piston 5 and 5 by the gap 15 formed between the radial outer contour of the piston 5 and the inner wall of the cylinder 4 the lid wall 4b of the cylinder 4 is displaced into it. When moving out of the plunger 6 from the cylinder 4, the liquid 10 flows back in the same way.

The cylinder 4 is surrounded by an electrical conductor coil 16. If this conductor coil 16 flows through an electric current, the result is an axially aligned magnetic field in the interior of the cylinder 4.

In order to block the movement of the piston 5 and thus of the plunger 6, the conductor coil 16 is energized. Due to the magnetic field generated in the process, the magnetorelogic fluid 10 in the interior of the cylinder 4 is solidified to such an extent that overflow from one side of the piston 5 to the other through the relatively narrow gap 15 is no longer possible.

Here it is important to achieve a suitable compromise between a sufficiently low-resistance overflow behavior in the de-energized state and a sufficiently effective blocking behavior with a justifiable energization. This is achieved inter alia by a suitable design of the cross-sectional contour of the piston 5 and the inner wall of the cylinder 4. By the here shown, in the broadest sense as a star shape to be designated cross-sectional shape a relatively large area of the gap 15 is achieved to improve the overflow behavior with a simultaneously small gap width to facilitate the blocking behavior.

Claims

claims 1. Electrical switching device for a motor vehicle, with a at least one axis (3a) pivotally mounted shift lever (1) and with at least one locking device, which can put a shift stop for the shift lever (1) in or out of force, characterized in that the locking device comprises hydraulically acting means. 2. Electrical switching device according to claim 1, characterized in that the locking device comprises a with an incompressible liquid (10) filled cylinder (4) in which a piston (5) is received axially displaceable, wherein the switching stop by fixing the piston (5 ) is put into effect in one position. 3. Electrical switching device according to claim 2, characterized in that with the piston (5), a plunger (6) is connected, which faces with its end face the shift lever (1) in its direction of movement. 4. Electrical switching device according to claim 2 or 3, characterized in that between the shift lever (1) facing away from the bottom wall (4a) of the cylinder (4) and the piston (5) a helical compression spring (7) is arranged, which the piston (5 ) with its spring force against the shift lever (1) facing the cover wall (4b) of the cylinder (4) presses. 5. Electrical switching device according to one of claims 2 to 4, characterized in that in the cylinder (4) existing incompressible liquid (10) is a magnetorheological fluid. 6. Electrical switching device according to claim 5, characterized in that the bottom wall (4a) of the cylinder (4) provided with an opening and this with a pipe (11) is connected, which opens into a reservoir, and that at one point of the pipeline (11) an electromagnet (12) is arranged so that the pipe (11) extends through an air gap in the yoke (13). 7. Electrical switching device according to claim 5, characterized in that between the radial outer contour of the piston (5) and the inner wall of the cylinder (4), a gap (15) is formed, through which the liquid (10) in the axial direction of the cylinder ( 4) from one side of the piston (5) to the other and can flow back again, and that the cylinder (4) by an electrical conductor coil (16) is electrically connected to generate a magnetic field in the interior of the cylinder (4) is currentable. 8. Electrical switching device according to one of claims 1 to 7, characterized in that the shift lever (1) in a universal joint (2) about two mutually perpendicular axes (3a) and (3b) is pivotally mounted, and that in its lower end a spring-loaded locking pin (8) is received, which is guided in a three-dimensional latching cam (9). 9. Electrical switching device according to one of claims 1 to 8, characterized in that a plurality of locking devices are provided to form a plurality of switching stops for different directions of movement and / or -ausschlage the shift lever (1). 10. Electrical switching device according to one of claims 1 to 9, characterized in that the shift lever (1) is a gear selector switch.