Park lock system for a motor vehicle transmission

Abstract

The present invention relates to a parking lock system (1) for a motor vehicle transmission, comprising a locking wheel (11) connected to a transmission element, a parking pawl (5) with a locking finger (6) designed to engage in a recess (10) of the locking wheel (11), a sliding fork head mounted in a housing (20) comprising side walls (22) connected by an edge (21). A device (30) for detecting the speed of the locking wheel (11) and / or the position of the parking pawl (5) and / or the position of the sliding fork head (8) is mounted on the housing (20). Figure for abstract: Figure 1

Description

Title of the invention: Park lock system for a motor vehicle transmission

[0001] The present invention relates to a parking lock system for a motor vehicle having an automatic transmission, such as a hybrid or electric vehicle.

[0002] Conventionally, a parking lock system comprises a locking wheel connected to a transmission element and a parking pawl having a locking finger adopting a locking position in which the locking finger is engaged in a recess of the locking wheel or an unlocking position in which the locking finger is disengaged from the recess. The parking lock system is connected to an actuator for transforming electrical energy into mechanical energy.

[0003] It is therefore necessary to know exactly the angular position and / or the number of revolutions per minute of the locking wheel in order to perfectly engage the locking finger in the recess of the locking wheel while avoiding a ratcheting effect which can lead to wear or even breakage of the parking locking system. It is not possible to rely on the vehicle speed due to the many tolerances in the transmission, to engage the parking pawl, especially at low vehicle speeds. This is even less achievable when the transmission has several gears due to the gear ratio.

[0004] The use of a wheel speed sensor is known from DE 10 2017 220 549 AL This wheel speed sensor is fixed somewhere in the transmission. Functional problems can be expected due to the considerable tolerance chain caused by the physically separate installation locations of the parking lock system and the wheel speed sensor leading to unreliable measurements.

[0005] It is also necessary to know exactly the position of the parking pawl to determine whether the parking pawl is in the locked or unlocked position. It is not possible to rely on the position of the actuator due to the many tolerances in the components between the actuator and the parking pawl.

[0006] The use of a parking pawl lock position sensor is known from DE 10 2009 023 498 AL This position sensor is fixed somewhere in the transmission. Functional problems can be expected due to the considerable tolerance chain caused by the physically separate installation locations of the parking lock system and the lock position sensor leading to unreliable measurements.

[0007] It is necessary to make these measurements more reliable, while facilitating the assembly and insertion of the parking lock system into the transmission.

[0008] The present invention relates to a parking lock system for a motor vehicle transmission, comprising a locking wheel connected to a transmission element, a parking pawl with a locking finger adapted to engage in a recess of the locking wheel, a sliding fork head adapted to alternately adopt a locking position, in which the sliding fork head pushes the parking pawl into a position for engaging the finger in the recess of the wheel to lock the transmission element, or an unlocking position, in which the parking pawl is returned to a position for disengaging the finger, the sliding fork head is mounted in a housing comprising side walls connected by a ridge,a device for detecting the speed of the locking wheel and / or the position of the parking pawl and / or the position of the sliding fork head is mounted on the housing.

[0009] The principle of the invention is to reduce as much as possible the dimensional chain between the detection device and the parking pawl or the locking wheel. The integration of the detection device directly on the housing solves the aforementioned problems.

[0010] According to the invention, it is possible to measure the speed of the locking wheel very precisely directly from the parking locking system and to send this information to the associated control unit. The control unit then decides whether the parking pawl can be engaged safely and without potentially damaging the components concerned.

[0011] According to the invention, it is also possible to measure the two most important positions of the parking pawl directly or indirectly and to send this information to the control unit. The control unit then decides whether the parking pawl is correctly engaged or disengaged safely and without potentially damaging the components concerned. The detection of the position of the parking pawl leads to a direct measurement and the detection of the position of the sliding fork head leads to an indirect measurement of the position of the parking pawl, since the parking pawl is linked to the position of the sliding fork head.

[0012] According to one aspect of the invention, the detection device is a reverse-biased Hall effect device having a magnet and a Hall element. This device can measure the speed of the locking wheel using the change in the magnetic circuit caused by the recesses of the ferromagnetic locking wheel. This device can also measure the two static positions of the parking pawl using the change in the magnetic circuit caused by the distance of the ferromagnetic parking pawl.

[0013] Alternatively, a Hall effect sensor or a magnetoresistive sensor may be used instead of the reverse biased Hall effect device.

[0014] According to another aspect of the invention, the detection device is mounted on one of the side walls. This arrangement ensures easier access to the locking wheel and / or the parking pawl.

[0015] According to a first embodiment of the invention, the housing is laterally traversed by a shaft around which the parking pawl is pivotally mounted and the detection device is mounted on this shaft and against one of the side walls. This arrangement facilitates the fixing of the detection device on the housing and the measurement of the speed of the locking wheel in a reliable manner.

[0016] According to the invention, the sliding fork head comprises a first roller and a second roller, each mounted to rotate freely about an axis, the first roller being positioned to roll against the parking pawl when the sliding fork head moves to the locking position, and the second roller being positioned to roll against the edge of the housing. Each side wall of the housing is perforated by at least one slot, preferably two slots for guiding the ends of the axis, the ends of the slots forming the stops for the locking and unlocking positions of the fork head.

[0017] According to a second embodiment of the invention, the detection device is located in the area of ​​the at least one slot and against one of the side walls. This arrangement facilitates the attachment of the detection device to the housing and the measurement of the position of the parking pawl and / or the sliding fork head reliably.

[0018] According to the invention, the detection device is fixed to the housing using fixing means, such as screws, glue, snap-fastening, etc.

[0019] According to the invention, the sliding fork head is pushed into the locking position by a spring and into the unlocking position by an actuator.

[0020] The present invention may be better understood with reference to the following description and drawings. In the drawings:

[0021] [Fig.l] illustrates a first embodiment of the parking lock system in which the detection device is mounted on the housing to detect the speed of the locking wheel;

[0022] [Fig.2] illustrates a second embodiment of the parking lock system in which the detection device is mounted on the housing to detect the position of the parking pawl.

[0023] In the following description, reference is made to the accompanying drawings, which are part thereof, and in which there are illustrated specific embodiments in which the invention may be applied. These embodiments are described in sufficient detail to enable a person skilled in the art to practice the invention, and it will be understood that the embodiments may be combined or other embodiments may be used and that structural and logical modifications may be made without departing from the scope of the present invention. The following detailed description should therefore not be construed as limiting and the scope of the present invention is defined by the appended claims and their equivalents.

[0024] [Fig.l] shows the parking lock system 1. It comprises a housing 20 made of at least one folded and cut sheet metal. The housing 20 comprises at least two tabs 3 for fixing, preferably one at the front and one at the rear, to a fixed part of the vehicle transmission. The housing 20 has two side walls and an edge 21 defining a “U” shape.

[0025] The housing 20 is traversed laterally by a shaft 4 around which a parking pawl 5 is pivotally mounted. The parking pawl 5 is thus arranged inside the housing 20, and is able to project from an open lower wall of the housing 20. The parking pawl 5 is provided, at one of its ends, with a locking finger 6 adapted to engage in a recess of a locking wheel rotatably connected to an output of the vehicle transmission.

[0026] The parking pawl 5 is held in, and returned to, a position of uncoupling of the finger 6 by means of an elastic return member 7, for example in the form of a torsion spring, arranged around the axis 4 of the parking pawl 5, and cooperating with fixed parts of the housing 20.

[0027] The housing 20 also internally comprises a fork head 8 slidably mounted to alternately adopt a locking position in which the fork head 8 pushes the parking pawl 5 into a position of engagement of the finger 6 in the recess of the locking wheel, in order to block the output of the transmission, and thus park the vehicle.

[0028] The fork head 8 is able to adopt another position, known as the unlocking position, in which it does not interfere with the parking pawl 5, allowing said parking pawl 5 to be returned by the elastic return member 7 to its position of uncoupling from the finger 6.

[0029] The fork head 8 is mounted at the end of a guide rod 9 passing through a rear wall of the housing 20. A compression spring, not shown, is mounted around the rod 9, between the rear wall of the housing 20 and the fork head 8, in order to push said fork head 8 into the locking position.

[0030] The parking locking system 1 cooperates with an actuator, not shown, positioned at an open front wall of the housing 20, and positioned to push the fork head 8 into its unlocking position, against the spring.

[0031] To guide the sliding fork head 8, the fork head 8 comprises a first roller 12 and a second roller 12, each mounted to rotate freely about an axis 13, the first roller 12 being positioned to roll against the parking pawl 5 when the fork head 8 moves to the locking position, and with the second roller 12 positioned to roll against a fixed wall of the system 1, and in particular against the edge 21 of the housing 20, opposite the parking pawl 5.

[0032] More specifically, the sliding fork head 8 takes the form of a cage inside which the first roller 12 and the second roller 12, as well as the guide rod 9, are housed in a floating manner. In particular, the fork head 8 has open upper and lower walls for the radial projection of the rollers 12.

[0033] In order to control the different positions, the axes 13 associated with the roller 12 project on either side of the rollers 12 to abut against fixed parts of the parking locking system 1 forming the stops for the locking and unlocking positions of the sliding fork head 8. The side walls of the housing 20 are each provided with two slots 14 serving to guide the ends of the axes 13, said ends of the slots 14 forming the stops defining the locking and unlocking positions.

[0034] The locking wheel 11 is a toothed wheel provided with teeth and recesses 10. The locking wheel 11 is ferrous. The detection device 30 is mounted on the housing 20 and opposite the locking wheel 11 in order to detect the speed of the locking wheel 11.

[0035] The sensing device 30 is a reverse-biased Hall effect device having a magnet 31 and a Hall element 32. The north pole of the magnet 31 faces the back of the Hall element 32. The sensing distance is measured between the Hall element 32 and the tip of the gear tooth of the locking wheel. The magnet 31 produces a changing magnetic field as the locking wheel 11 moves past the Hall element 32. The changing magnetic field is collected and processed into a signal defining the rotational speed of the locking wheel 11 and the exact angular position. The sensing device 30 is electrically powered using a cable 15, this cable 15 also transmitting the signal to the control unit, not shown.

[0036] [Fig. 2] shows a variant of the parking lock system 1' in which the detection device 30 is located at the front of the parking lock system 1' in the area of ​​the slots 14. Only the location of the detection device 30 and the purpose are different from those of [Fig. 1]. The elements in common will not be described again here. The parking pawl 5 is ferrous. The detection device 30 is mounted on the housing 20 and opposite the parking pawl 5 in order to detect the locking or unlocking position of the parking pawl 5.

[0037] The detection device 30 is similar to that described in connection with [Fig. 1] with a magnet 31 and a Hall element 32. The magnet 31 produces a changing magnetic field as the parking pawl 5 moves past the Hall element 32 depending on the position. The change in magnetic field is collected and processed into a signal defining the exact position of the parking pawl 5. The detection device 30 is electrically powered using a cable 15, this cable 15 also transmitting the signal to the control unit, not shown.

Claims

Claims

1. Parking lock system (1) for a motor vehicle transmission, comprising a locking wheel (11) connected to a transmission element, a parking pawl (5) with a locking finger (6) designed to engage in a recess (10) of the locking wheel (11), a sliding fork head (8) intended to alternately adopt a locking position, in which the sliding fork head (8) pushes the parking pawl (5) into a position for engaging the finger (6) in the recess (10) of the wheel (11) to lock the transmission element, or an unlocking position, in which the parking pawl (5) is returned to a position for disengaging the finger (6), the sliding fork head (8) is mounted in a housing (20) comprising side walls (22) connected by a ridge (21),characterized in that a device (30) for detecting the speed of the locking wheel (11) and / or the position of the parking pawl (5) and / or the position of the sliding fork head (8) is mounted on the housing (20).,

2. A parking lock system (1) according to claim 1, characterized in that the detection device (30) is a reverse-biased Hall effect device having a magnet (31) and a Hall element (32).

3. Parking lock system (1) according to claim 1, characterized in that the detection device (30) is a Hall effect sensor or a magnetoresistive sensor.

4. Parking locking system (1) according to one of the preceding claims, characterized in that the detection device (30) is mounted on one of the side walls (22).

5. Parking locking system (1) according to one of the preceding claims, characterized in that the housing (20) is laterally traversed by a shaft (4) around which the parking pawl (5) is pivotally mounted, the detection device (30) is mounted on this shaft (4) and against one of the side walls (22).

6. A parking locking system (1) according to any preceding claim, characterized in that the sliding fork head (8) comprises a first roller (12) and a second roller (12), each mounted to rotate freely. around an axis (13), the first roller (11) being positioned to roll against the parking pawl (5) when the sliding fork head (8) moves to the locking position, and the second roller (12) being positioned to roll against the edge (21) of the housing (20).

7. Parking locking system (1) according to claim 6, characterized in that each side wall (22) is perforated by at least one slot (14), preferably two slots (14) serving to guide the ends of the axis (13), the ends of the slots (14) forming the stops for the locking and unlocking positions of the fork head (8).

8. Parking locking system (1) according to claim 7, characterized in that the detection device (30) is located in the area of ​​the at least one slot (14) and against one of the side walls (22).

9. Parking locking system (1) according to one of the preceding claims, characterized in that the detection device (30) is fixed to the housing using fixing means.

10. Parking locking system (1) according to one of the preceding claims, characterized in that the sliding fork head (8) is pushed into the locking position by a spring and into the unlocking position by an actuator.

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