192 clutches and power-stop control – Transmission and brake – Motor vehicle
Reexamination Certificate
1999-09-07
2001-08-14
Bonck, Rodney H. (Department: 3681)
192 clutches and power-stop control
Transmission and brake
Motor vehicle
C192S222000
Reexamination Certificate
active
06273232
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electric parking lock device having a drive force generating means for engagement and/or release of a parking lock pawl with and/or from a parking lock gear in response to a command from a parking command means.
2. Description of the Related Art
With a vehicle in which the power from an engine is transmitted to driving wheels via a torque converter or a vehicle designed to be driven with an electric motor, it is not possible to utilize internal friction of the engine for locking the driving wheels. To cope with this, for instance, Japanese Patent Unexamined Publication No. HEI 8-216844 proposes an electric parking lock device in which a parking lock pawl is provided for engagement with and/or release from a parking lock gear provided on an output shaft of a transmission, and in which the parking lock pawl is operated by an electric actuator so as to lock driving wheels when the vehicle is stopped.
However, it is common with the electric actuator to adopt a construction which does not permit reverse driving through utilization of a screw means for transforming rotational motion of a motor to linear motion or interposition of a speed reducer to make the number of revolutions of an output shaft coincide with the operational angle of a parking lock pawl. Although this obviates the necessity of any special means for retaining he parking lock pawl at a regulated position, it follows that where the motor gets out of operation due to reduction in voltage of a battery or failure of an electrical system while the parking lock pawl is in engagement with the parking lock gear, it becomes difficult to release the parking lock pawl from the parking lock gear. Although the device disclosed in the aforesaid Japanese patent unexamined publication is provided with a manual lock release means, since the release means is constructed such that rotation force is applied to a gear shaft of the speed reducer, the construction becomes very complicated and production cost tends to be increased.
SUMMARY OF THE INVENTION
The present invention was made to solve problems as described above, and a primary object thereof is to provide an electric parking lock device provided with a manual lock release means of a simple construction. In addition, a secondary object of the present invention is to provide an improved electric parking lock device which can securely signal that there occurs a failure of a source of driving force for operation of the parking lock pawl when such really happens and is free from a risk of any failure or malfunction even if the manual lock release means fails to be properly operated.
With a view to attaining the above objects, in the present invention, there is provided an electric parking lock device, including: a drive source generating a drive force for engagement and release of a parking lock pawl with and from a parking lock gear in response to an output from a parking command unit; a spring unit provided along a force transmission path between an output end of the drive source and an input end of the parking lock pawl, for generating a biasing force directed so as to bring the parking lock pawl into engagement with the parking lock gear, the spring unit being maintained without deflecting until the parking lock pawl is at least engaged with the parking lock gear when a force which is directed to bring the parking lock pawl into engagement with the parking lock gear is applied to the parking lock pawl, the spring unit being deflectable by a distance equal to a stroke sufficient for at least releasing the parking lock pawl from the parking lock gear when a force which is directed so as to release the parking lock pawl from the parking lock gear is applied to the parking lock pawl; and a manual lock release unit for applying a force directed to release said parking lock pawl from the parking lock gear at the force transmission path on a side thereof which is closer to the input end of the parking lock pawl than to the spring unit. According to this construction, the driving of the parking lock pawl toward the lock release direction is effected in a state in which the drive source side and the parking lock pawl side are direct connected, and the driving of the same toward the lock execution direction is performed in a state in which the spring unit is interposed between the drive source side and the parking lock pawl side. Thus, if a manual operation force is applied to the parking lock pawl, the parking lock pawl can be displaced within a range in which the spring unit is deflected irrespective of the state of the drive source.
In particular, the electric parking lock device according to the present invention further includes an output side member position detection unit for detecting an output side member interlockingly connected to the output end of the drive source and both displacement limit positions of the outside member, and an input side member position detection unit for detecting an input side member interlockingly connected to the input side of the parking lock pawl and both displacement limit positions of the input side member, wherein the drive source is controlled in response to an output from these two position detection units. According to this construction, since operating conditions on the drive source side and the parking lock pawl side can be detected individually, detection and signaling of a failure and a malfunction can securely be performed, and thus a so-called fail-safe can properly secured.
REFERENCES:
patent: 5696679 (1997-12-01), Marshall et al.
patent: 5704457 (1998-01-01), Kimura et al.
patent: 5827149 (1998-10-01), Sponable
patent: 9-216844 (1996-08-01), None
Kima Yasuo
Kimura Kenichiro
Kimura Kiyoshi
Kondo Shugo
Namiki Toru
Armstrong Westerman Hattori McLeland & Naughton LLP
Bonck Rodney H.
Honda Giken Kogyo Kabushiki Kaishi
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