The disclosure relates to a reset device for a gearshift lever in a motor vehicle. In particular, the disclosure relates to the sensing of a position of an element of the reset device.
A motor vehicle comprises a transmission having numerous gear steps. An operation of the transmission can be influenced by a driver of the motor vehicle by means of a gearshift lever. By way of example, a manual program can be selected, in which the driver must explicitly trigger a gear change of the transmission via the gearshift lever. Alternatively, an automatic program may be selected, in which a control device carries out the selection and engagement of gear steps in the transmission. The programs can likewise be selected by means of the gearshift lever. In order to be able to start the motor at the start of a drive, the automatic program must be preset. For this, the gearshift lever can be slid from the manual program into the automatic program at the position N during the previous parking of the vehicle for example. Furthermore, the same mechanism can lock the gearshift lever in place, and also prevent, for example, a tilting movement back into the manual program, depending on the operating state (e.g. ignition is off).
A reset device for engaging the automatic program comprises an actuator, the position of which must be detected in order to ensure that the resetting has been correctly and completely carried out, and that the reset mechanism has returned to its end position/starting position. Known sensors in the gearshift lever, which can be used to sense the position of the reset device, comprise switches or hall effect sensors. These elements are relatively expensive to manufacture, however, and may exhibit an increased failure probability, such that the reset device is less reliable.
JP 2008-256693 discloses an assembly having three flat, horizontally offset coils, which can be influenced by a rhombus-shaped eddy current element. As a result, the position of the element can be determined in relation to the coils, but the necessary circuitry and mechanical expenditure for determining the position is relatively high.
The object of the present disclosure is to provide a reset device having an improved position determination for a gearshift lever of a motor vehicle. The disclosure achieves this objective by means of a reset device having the features of the independent Claim. The dependent Claims describe preferred embodiments.
A reset device for a gearshift lever for a gear step of a transmission in a motor vehicle comprises an electric drive device for controlling an operating element in order to move the gearshift lever into a predetermined position, a position sensor for determining a position of the operating element, and an electric activation device for activating the drive device depending on the position of the operating element. The position sensor comprises a first coil thereby, which is attached to the activation device, and a magnetic flux element is mechanically coupled to the operating element. The drive device is disposed with respect to the activation device, such that the flux element affects the inductivity of the first coil depending on a position of the operating element.
Preferably, a dynamic magnetic field is generated by the first coil, which is affected by the flux element, such that the presence of the flux element in the region of the first coil can be determined based on an electrical parameter at the coil. In particular, the inductivity of the first coil can be increased or decreased, when the flux element is moved closer to the first coil.
By attaching the first coil directly to the activation device, costs can be reduced, and the reliability of the position sensor can be increased. The arriving at one or more end positions of the operating element can thus be easily and reliably detected with less effort. An installment and/or adjustment of the first coil can be carried out inexpensively.
The activation device preferably comprises a printed circuit board, wherein the first coil is designed as a conductive path on the printed circuit board, in particular a spiral conductive path. As a result, a separate coil is not necessary. With a reduced use of materials and production costs, the reset device can be produced in a less expensive manner. Furthermore, connection points can be eliminated, such that the reliability of the reset device can be increased. The coil can be more easily protected on the printed circuit board, for example, by means of a cover, such that it is not susceptible to moisture, corrosion and electrical contact.
In a preferred embodiment, the position sensor comprises a second coil, which is attached to the activation device such that its inductivity is not affected by a position of the operating element, wherein the position sensor is configured to determine the position of the operating element based on a difference in the inductivities of the coils. As a result, a differential determination of the position of the operating element can be carried out, which can offer a high degree of precision or reliability. A measurement principle of this type is described in EP 1 884 749 A1. By using this measurement principle for the reset device, a particularly inexpensive and reliable integrated solution can be created, which can ensure that the gearshift lever will be correctly reset.
In one embodiment, at least one other position sensor is provided for determining a position of a gearshift lever. The at least one other position sensor can function according to the same measurement principle in particular, wherein shared structural elements may be used in multiple instances. By way of example, the at least one other position sensor may comprise a third coil, the inductivity of which depends on the position of the gearshift lever, while the second coil is not affected by a position of the gearshift lever. The position of the gearshift lever is determined thereby based on a difference in the inductivities of the second and third coils.
By means of the multiple use of the second coil, the relative effort for determining the position of the operating element can be reduced. System costs for the reset device can thus be lowered. In particular in one embodiment, in which the coils are excited to electromagnetic oscillations independently of one another, the frequencies of which are numerically compared, a complementary influencing of the first and second coils, or an influencing of the second coil by one of the moving elements is practically eliminated. The determinations of the position can thus be carried out with limited effort, without reciprocity, and in a reliable manner.
In order to influence the inductivity of the first coil, the flux element is configured in different variations to amplify or reduce the magnetic field provided by the first coil when the flux element is brought closer to the first coil. As a result, the inductivity of the first coil can change accordingly. An amplification or reduction by a predetermined factor, or beyond a predetermined threshold value, can be used for determining the presence or absence of the flux element at the coil, such that a binary result can be obtained, in the manner of a switch. If the flux element comprises a section having a magnetically soft substance, then this section can amplify the magnetic flux in the region of the first coil, when it is brought into the proximity of the first coil, and thus increase the inductivity of the first coil. If the flux element comprises, on the other hand, a section having an electrically conductive material, the magnetic field or the magnetic flux in the region of the first coil can be reduced when the section is brought into the proximity of the first coil. The inductivity of the first coil decreases thereby. The conductive material is preferably not ferromagnetic, e.g. copper, aluminum, or gold or another highly conductive metal may be used, potentially also in the form of an alloy.
Both variations can each be implemented in a cost-effective manner, independently of one another. The magnetically soft substance can comprise, e.g., ferrite, soft iron, an iron alloy or a special magnetically soft material such as Mu-metal. Fundamentally, the material requires good high-frequency properties. For this, the conductivity and the cyclic magnetization losses of the material must be low, but the permeability must be high. In one embodiment, the conductive material is attached to the operating element as a separate flux element. In another embodiment, the operating element comprises a section made of conductive material, which can be used as a flux element.
In order to determine the position, an arrangement of numerous sections of flux elements may be provided, wherein each section can comprise a magnetically soft substance, an electrically conductive material, or a material that leaves the inductivity of the first coil unaffected. The last of these can be implemented, in particular, by means of an appropriate cavity, or boundary of the flux element.
The sections can be moved past the first coil successively, when the operating element is operated, wherein the position of the operating element is determined incrementally, based on a temporal course of inductions at the first coil. The principle of a digital incremental encoder can thus be applied to the determination of the position of the operating element. As a result, a high position resolution of the operating element can be determined with limited effort.
In another embodiment, numerous first coils are provided, wherein the arrangement is moved past the first coils when the operating element is operated. The position of the operating element is determined absolutely thereby, based on a combination of inductions of the first coil. The position of the operating element can be digitally encoded through the position of the sections in relation to the first coil, such that a high determination precision of the position of the operating element can be obtained. In yet another embodiment, two flux elements are provided, which lie opposite one another with respect to the printed circuit board. As a result, the affect on the first coil attached to the printed circuit board can be amplified by the two flux elements.
In yet another embodiment, two first coils are provided, which lie on different planes of the printed circuit board. The first coils can be electrically interconnected, for example, by means of interlayer connections, in particular electrically in series. As a result, the two first coils can be regarded as a first coil having an increased number of windings. In this manner, the inductivity of the entire coil can be more easily changed by the flux element.
The disclosure shall now be explained in greater detail with reference to the attached Figures, wherein:
In a left-hand shift gate, which corresponds to a manual shift gate, the positions M, T+ and T− are depicted vertically. If the gearshift lever 105 is in the position M, as depicted, then it can be moved by the driver into the position T+, in order to cause an upshifting of the transmission, or in the T− position, in order to cause a downshifting. After releasing it, the gearshift lever 105 normally returns to the position M by means of spring force.
Regardless of the precise arrangement of different positions 110, the control system 100 is configured to bring the gearshift lever 105 into a predetermined position 110, under predetermined conditions, in particular from a position 110 in the manual shift gate, into a position 110 in the automatic shift gate. In the present circumstances, the gearshift lever 105 can be moved, for example, from the position M into the position N, when the motor vehicle is parked. A reset device 115 is provided for the movement, which comprises an electric drive device 120 and an operating element 125, wherein the drive device 120 is configured to operate the operating element 125, in order to move the gearshift lever 105 into the predetermined position 110. Furthermore, the reset device 115 comprises a position sensor 130, which functions according to the inductive measurement principle.
The position sensor 130 comprises a coil 135, which is stationary in relation to the drive device 120, and a magnetic flux element 140, which is stationary in relation to the operating element 125. An activation device 145 is configured to activate the drive device 120 in response to a signal from the position sensor 130. The activation can occur in response to a signal, in particular, which can be received at an interface 150. It is preferred thereby that the coil is attached directly to the activation device 145. In particular, it is preferred that the activation device 145 comprises a printed circuit board, onto which the coil 135 is attached. The coil 135 can be designed, in particular, in the form of a printed circuit, wherein a circuit path made of a conductive material is formed in a plane, in concentric windings. It is also possible to provide numerous coils, which are connected to one another, and are disposed in different planes, above one another, and connected electrically to one another.
The position sensor 130 preferably has the function of a limit switch, which senses in a binary manner whether the operating element 125 has or has not reached a predetermined position. For this, a sensing value can be compared with a threshold value. In other embodiments, a digital position determining using more than two values can also be carried out for the operating element 125. Analog position determinations, i.e. continuous, can also be carried out.
A differential measurement method can be used, in which another coil 160 is provided, the inductivity, or magnetic field, respectively, of which remains unaffected by a position of the flux element 140. The inductivities of the coils 135 and 160 can then be compared with one another, in order to determine, in an analog or digital manner, the position of the flux element 140, and thus the operating element 125. By way of example, two oscillating circuits can be created with the coils 135 and 160, the frequencies of which can be determined and compared with one another.
In a particularly preferred embodiment, another one or more coils 165 can be comprised by the reset device 115, wherein the additional coil 165 can be configured for sensing the position of the gearshift lever 105, for example. For this, the gearshift lever can comprise a flux element, or be mechanically coupled to a flux element. It is particularly preferred that the third coil 165 is directly attached to the activation device 145, in particular as a printed coil on the printed circuit board 155.
A complementary embodiment to the embodiment in
In the embodiments in
It is possible in general to design the magnetic flux element 140 to either amplify or dampen a magnetic field of the first coil 135. An amplification can be obtained, for example, by means of a magnetically soft material, while a damping can be caused by means of a conductive, preferably non-ferromagnetic material such as copper or aluminum. Eddy currents can be formed in the material thereby, by means of the magnetic field, which reduce the magnetic field, or the magnetic flux. In one embodiment, a mechanical element of the reset device 115 is already formed from an appropriate material, such that the element need only be formed in accordance with one of the options in
Number | Date | Country | Kind |
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DE102014211376.8 | Jun 2014 | DE | national |
DE102014212058.6 | Jun 2014 | DE | national |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2015/061349 | 5/22/2015 | WO | 00 |