Interrelated power delivery controls – including engine control – Transmission control – With clutch control
Reexamination Certificate
2000-02-23
2001-09-11
Wright, Dirk (Department: 3681)
Interrelated power delivery controls, including engine control
Transmission control
With clutch control
C192S01800B
Reexamination Certificate
active
06287236
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a parking brake apparatus for industrial vehicles.
Like ordinary automobiles, industrial vehicles, such as forklifts, have a service brake and a parking brake. The service brake is used for controlling speed when the vehicle is moving and for stopping the vehicle. The parking brake is for maintaining the vehicle in a stationary position when the vehicle engine is not in gear. The parking brake is connected to a parking lever by a cable or a link. The parking lever is manipulated by a hand or a foot. A manipulation force applied to the lever is transmitted to the parking brake by the cable or the link.
Japanese Unexamined Patent Publication No. 6-247190 discloses an industrial vehicle having an auxiliary brake. The vehicle has a transmission, which includes a torque converter and hydraulic forward and reverse clutches. The auxiliary brake is located in the transmission. When the vehicle is moving and handling a load at the same time, the handling speed of the load is controlled based on the manipulation amount of a loading lever. Specifically, the engine throttle is controlled by manipulating the loading lever. The load manipulation speed is controlled based on the engine throttle. The vehicle speed is set to a target value regardless of the engine speed. The target value of the vehicle speed is determined based on the depression amount of an acceleration pedal. That is, the braking force of the auxiliary brake and the engagement of one of the forward and backward clutches are controlled such that the vehicle speed matches the target value.
The parking brake is switched between a parking position and a release position by manipulating a parking brake lever. The parking brake lever takes up space in the operator cab, which reduces the space for other accessories and limits the flexibility of the design.
When parking the vehicle the operator must switch the parking lever to the braking position and when starting the vehicle must release the lever to the release position, which makes the operation troublesome. When temporarily stopping the vehicle on a sloped road, the operator must either use the parking brake or keep the brake pedal depressed to actuate the service brake, which also makes the operation troublesome. If the operator only uses the service brake when temporarily stopped on a sloped road, releasing the brake pedal causes the vehicle to move away from the desired location.
The vehicle disclosed in Japanese Unexamined Patent Publication No. 6-247190 has the auxiliary brake in addition to the service brake. However, the auxiliary brake cannot be used as a parking brake. Thus, when temporarily stopping the vehicle on a sloped road, the operator must keep the brake pedal depressed or use the parking break.
SUMMARY OF THE INVENTION
Accordingly, it is an objective of the present invention to provide a parking brake apparatus that eliminates the necessity for a parking lever and also eliminates the necessity for continuously depressing a brake pedal when temporarily stopping a vehicle on a slope.
A second objective of the present invention is to provide a parking brake apparatus for industrial vehicles that prevents the vehicle from being moved in an undesirable direction when the parking brake is released when the vehicle is on a sloped road.
A third objective of the present invention is to provide a parking brake device for industrial vehicles that permits the vehicle to creep after the parking brake has been released after having temporarily stopped the vehicle when moving very slowly, by changing the force applied to the brake controller.
To achieve the foregoing and other objectives and in accordance with the purpose of the present invention, a parking brake apparatus for an industrial vehicle is provided. The apparatus includes a braking member for maintaining the industrial vehicle in a stationary position, holding means for holding the braking member in an engaged state, releasing means for releasing the braking member from the engaged state and first detection means for detecting the speed of the vehicle and generating a speed indication signal. The apparatus further includes determination means and control means. The determination means determines whether the vehicle speed is equal to or less than a predetermined value based on the speed indication signal from the first detection means, and generates a first determination signal. The control means controls the releasing means to engage the braking member, based on the first determination signal.
The present invention may also be embodied in an industrial vehicle having a parking brake for maintaining the industrial vehicle in a stationary position. The vehicle includes holding means for holding the parking brake in an engaged state, releasing means for releasing the parking brake from the engaged state and a vehicle speed detector for detecting a speed of the vehicle. The vehicle also includes determination means and a controller. The determination means determines whether the vehicle speed is equal to or less than a predetermined value based on a signal from the speed detector. When the controller detects that the vehicle speed is equal to or less than the predetermined value based on a determination signal from the determination means, the controller controls the releasing means to engage the parking brake.
Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.
REFERENCES:
patent: 5053960 (1991-10-01), Brekkestran et al.
patent: 5918509 (1999-07-01), Heilig et al.
patent: 010132952-A (1989-02-01), None
patent: 01030862-A (1989-02-01), None
patent: 06-247190 (1994-09-01), None
Kabushiki Kaisha Toyoda Jidoshokki Seisakusho
Morgan & Finnegan , LLP
Wright Dirk
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