Fluid-pressure and analogous brake systems – Multiple control – Fluid and electric
Reexamination Certificate
2000-06-15
2002-04-09
Schwartz, Christopher P. (Department: 3613)
Fluid-pressure and analogous brake systems
Multiple control
Fluid and electric
C303S022500, C303S007000
Reexamination Certificate
active
06367887
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of co-pending German Patent Application No. 199 28 113.0 entitled “Anhängerbremsventil far blockiergeschützte Druckluftbremsanlagen von Anhängern” filed on Jun. 19, 1999.
FIELD OF THE INVENTION
The present invention generally relates to a brake valve. More particularly, the present invention relates to a trailer brake valve to be used in a compressed air brake system of a trailer of a truck. The brake system or the brake assembly of the trailer includes an anti lock control unit (ABS control unit) and a load sensing control unit (ALB control unit). The trailer brake valve is a control valve being designed as a relay valve and being arranged at the trailer of the truck. The trailer brake valve serves to control brake pressure in the region of the brake of the trailer of the truck. The trailer itself also includes an anti lock system. Additionally, the trailer includes at least one sensor indicating the load of the trailer and providing a corresponding signal. In case the trailer includes a suspension or a pneumatic cushioning, the sensor may simply sense the pressure in a filling conduit being connected to a suspension bellow.
BACKGROUND OF THE INVENTION
A trailer brake valve is known from German patent No. 35 19 182 C2. The trailer brake valve includes a relay piston being guided in a housing. The relay piston defines a control chamber and a brake chamber in the housing. The brake conduit of the trailer is connected to the control chamber. The brake chamber includes connections for conduits leading to brake cylinders.
The known trailer brake valve includes an inlet valve and an outlet valve including a common double valve body. The inlet valve is located adjacent a reservoir chamber being permanently connected to a reservoir conduit leading to the trailer and to a reservoir at the trailer.
The known trailer brake valve includes an anti lock electronic control unit being integrated into the housing of the trailer brake valve. A pressure/voltage converter detects the control pressure prevailing in the brake conduit, and it is electrically connected to the anti lock electronic control unit to transmit the signal. The known trailer brake valve includes a solenoid valve. The solenoid valve is arranged in the brake conduit leading to the control chamber of the relay piston, and it has a special design.
The known solenoid valve has three possible positions. In the non-excited position of the known solenoid valve, there is a passage in the brake conduit in the direction of the control chamber of the relay piston. In a first excited position of the known solenoid valve, this passage is blocked and a conduit leading to an expansion space is also blocked. In a second excited position of the known solenoid valve, the brake conduit is blocked and the side of the entrance, again, but the connection to the expansion space is freed such that the pressure prevailing in the control chamber is correspondingly reduced. The expansion chamber may be connected to the atmosphere by a throttling bore.
The known trailer brake valve includes a steering mechanism for a load signal. This means that it includes the connection of a mechanical adjustment drive, the position signal of which is fed into the anti lock electronic control device such that the solenoid valve and its inlet, respectively, is closed in steps corresponding to the present load of the trailer. Due to the connection of the control chamber to the expansion space, it is possible to reduce the pressure by one corresponding step. The value of this step depends on the volume of the expansion space.
In many cases, it is not sufficient to reduce the control pressure by one step by a connection of the control chamber to the expansion space. The connection of the expansion space to the atmosphere via a throttling bore has the effect of the pressure being reduced in the expansion space. Nevertheless, the pressure often is not reduced fast enough to remain under the locking limit in the anti lock operating modus.
With the known trailer brake valve, the effect of the load signal (ALB signal) is lost when the power supply of the anti lock electronic control unit (ABS electronic control unit) fails. Thus, the trailer only brakes pneumatically. There is the danger of the trailer braking too much and of the wheels of the trailer locking, respectively.
A brake assembly for pneumatically braking trailers is known from German patent application No. DE 44 25 789 A1. The brake assembly includes an electronic control unit for an anti lock control not only processing anti lock signals (ABS signals), but also additionally processing load signals (ALB signals). When the power supply of the known electronic control unit fails or in case of a different defect occurring in the electronic control unit, the anti lock signal and the load signal do not have an effect any more. In case of such a defect occurring and a brake signal being sent to the trailer by the trailer control valve being located at the truck, the trailer brake pressure is no longer adapted to the driving conditions.
It is also known to use two solenoid valves with prior art relay valves being operated together with an anti lock electronic control unit. The solenoid valves are either located on the truck or on the trailer. The first solenoid valve serves to aerate the control chamber of the relay valve, and the second solenoid valve serves to deaerate the control chamber of the relay valve.
Typically, it is known in the art to use two solenoid valves at one relay valve when an anti lock signal is processed and when the pressure prevailing in the control chamber of the relay valve is to be increased, decreased or kept constant for a limited period of time.
SUMMARY OF THE INVENTION
Briefly described, the present invention provides a trailer brake valve. The trailer brake valve is to be mounted in a compressed air brake system of a trailer of a truck. The brake system of the trailer includes an anti lock control unit and a load sensing control unit. The trailer brake valve includes a housing and a relay piston being movably guided in the housing. A control chamber is located in the housing. A brake chamber is located in the housing, and it includes connections for conduits leading to brake cylinders of the brake system in which the trailer brake valve is to be mounted. The control chamber and the brake chamber are defined and limited by the relay piston. A brake conduit is connected to the control chamber. A reservoir chamber is located in the housing and an inlet valve is located adjacent the reservoir chamber. An outlet valve is located in the housing. A first solenoid valve is arranged in the brake conduit and a second solenoid valve is designed and arranged to deaerate the control chamber. A first pressure/voltage converter is designed and arranged to sense control pressure prevailing in the brake conduit and a second pressure/voltage converter is designed and arranged to sense pressure prevailing in a region adjacent the relay piston. A load sensing control unit is designed and arranged to produce a load signal and an independent electronic control unit is designed and arranged to control the first and second solenoid valve exclusively with the load signal produced by the load sensing control unit.
The present invention is based on the concept to separate the processing of the anti lock signal (ABS signal) from the processing of the load signal (ALN signal) in a compressed air brake assembly of a trailer including an anti lock control unit and a load sensing control unit, and to provide the trailer brake valve with its own electronic control being designed and destined to exclusively process load signals. The trailer brake valve includes two solenoid valves of which the first serves to aerate the control chamber and of which the second serves to deaerate the control chamber. Consequently, a great variety of possible control philosophies are realized for the trailer brake valve.
With the novel brake valve of a trailer of a t
Haldex Brake Products GmbH
Nguyen Xuan Lan
Schwartz Christopher P.
LandOfFree
Trailer brake valve does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Trailer brake valve, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Trailer brake valve will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2833137