Brakes – Wheel – Axially movable brake element or housing therefor
Patent
1997-09-25
1999-09-21
Oberleitner, Robert J.
Brakes
Wheel
Axially movable brake element or housing therefor
188265, 188 725, F16D 526
Patent
active
059541628
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a combined service and parking brake, in particular for automotive vehicles.
A combined service a nd parking brake is disclosed in German patent application No. 37 32 303. The prior art brake has a hydraulic actuating device configured as a brake cylinder with two brake pistons which are movable in opposite directions. The brake cylinder is connected to the remaining brake system of a vehicle by way of a first hydraulic supply line. A second hydraulic supply line leads to a hydraulically operable locking device in the form of an auxiliary cylinder arranged at right angles relative to the brake cylinder. The auxiliary cylinder has an auxiliary piston adapted to slide a wedge between the two first-mentioned brake pistons in the brake cylinder in order to lock the two brake pistons in the applied condition. The disadvantage of the prior art arrangement is that two hydraulic supply lines are necessary for each brake. This increases the expenditure in material and assembly to a considerable extent.
Also, combined service and parking brakes are known in which a hydraulic actuating device is provided for service brake operations and mechanically operable locking devices are provided as parking brakes. However, the disadvantage of arrangements of this type is that an additional brake cable is required for each brake beside the hydraulic supply line. Further, this necessitates an increased expenditure in material and manufacture. In addition, the brake cable can only be fitted subsequent to mounting the brake on the vehicle. Normally, the assembly is not carried out by any competent brake manufacturer but is generally done by car makers. Apart from the shortcoming of an increased assembly effort, car makers additionally bear the risk of a wrong assembly.
SUMMARY OF THE INVENTION
An object of the present invention is to simplify a combined service and parking brake with respect to the operation of the locking device to the effect of reducing in particular the effort needed for the assembly of the brake on the vehicle.
This object is achieved by using the same hydraulic supply line for operation of the service brake and for operation of the locking device and achieving the separation in terms of functions by selecting different pressure ranges for the different functions.
In a preferred aspect of the present invention, the hydraulic pressure for service brake operations is in the range of 0 to 150 bar, while a pressure impact in the range of more than 200 bar is required for the operation of the locking device. In other respects, the hydraulic pressure for service brake operations lies in the conventional range so that no modification to the brake system is necessary.
To prevent inadvertent release of the locking device, the brake piston is adapted to be locked relative to the brake cylinder by mechanical locking means. However, locking the brake piston relative to the brake cylinder by frictional engagement is also within the scope of the present invention.
In a preferred aspect of the present invention, the locking means of the locking device are operable by a hydraulic auxiliary piston. The auxiliary piston has a considerably smaller cross-sectional surface than the brake piston so that a high amount of hydraulic pressure is required to generate the actuating forces for the actuation of the locking means. Besides, the auxiliary piston can be acted upon by a resetting spring in opposition to the actuating direction.
A resetting spring of this type is particularly favorable in connection with the preferred aspect that the auxiliary piston is moved by a first pressure impact in the actuating direction, and the movement is transmitted to the locking means by way of a mechanical transmission device which has an accumulator function. The locking means cause locking engagement between the brake piston and the brake cylinder. After the pressure impact, the auxiliary piston returns to its initial position by the action of the resetting spring, while the mecha
REFERENCES:
patent: 3874747 (1975-04-01), Case et al.
patent: 4116113 (1978-09-01), Leclerc
patent: 4116307 (1978-09-01), Reainecke
patent: 4212167 (1980-07-01), Pruett
patent: 4215767 (1980-08-01), Shirey
patent: 4412603 (1983-11-01), Bischoff
patent: 4873824 (1989-10-01), Cox
Feigel Hans-Jorg
Rieth Peter E.
ITT Manufacturing Enterprises Inc.
Oberleitner Robert J.
Siconolfi Robert A.
LandOfFree
Combined service and parking brake does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Combined service and parking brake, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Combined service and parking brake will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-72374