Patent Application
20060119174
This invention was not made by an agency of the United States Government nor under contract with an agency of the United States Government.
This invention relates generally to antilock brake systems for use in vehicles, and more specifically to distributed or modular system architecture for use with antilock air brake systems installed on commercial vehicles such as trucks.
Many modern vehicles include antilock brake systems (ABS) as standard equipment. In general terms, antilock braking systems are electronic systems that monitor and control wheel slippage during vehicle braking. Antilock brakes can improve vehicle control during braking events and can reduce stopping distances on slippery surfaces by limiting wheel slippage and minimizing wheel lockup. Rolling wheels have much greater traction than locked wheels. Thus, reducing wheel slip improves vehicle stability and control during braking, because stability typically increases as wheel slip decreases. A typical ABS consists of several key components, including an electronic control unit (ECU), multiple modulator valves, and multiple wheel speed sensors.
In terms of reliability, the wiring harness used to connect the various ABS components may prove problematic, due in part to its placement on the vehicle's chassis. The vehicle chassis is often a harsh environment for electrical conductors and connections. Furthermore, the overall reliability of the system decreases proportionally to the number of wires, wire length, and number of electrical connections present on the vehicle. Current ABS systems include a multitude of wires and connections placed throughout the vehicle and any failure of these connections may result in system failure and loss of ABS. Correctly mounting and connecting these various components also poses a challenge for the vehicle integrator. Since the ABS components are typically installed and connected when the vehicle is being assembled, there are multiple time points at which incorrect or incomplete electrical connections may occur. Thus, there is a need for an ABS architecture that minimizes the exposure of the wiring harness to potentially destructive environmental conditions and that increases the likelihood that the system will be properly installed at the time of vehicle assembly.
Deficiencies of the prior art are overcome by the present invention, the exemplary embodiment of which provides a distributed antilock brake system for use in a vehicle such as a van, truck, or bus that utilizes air brakes. The configuration of the system components in the present invention reduces the sizing and length of the wiring used and significantly reduces the number of connections made while installing the system on a vehicle.
The exemplary architecture of the system of the present invention includes a first control module and a second control module. The first control module is in communication with at least one brake and at least one sensor. The sensor is in communication with at least one wheel, and the first control module controls the brake in response to information received from the sensor. The second control module is in communication with at least one brake and at least one sensor. The sensor is in communication with at least one wheel, and the second control module controls the brake in response to information received from the sensor. The second control module is in communication with the first control module.
In operation, the first control module is in communication with the vehicle's front wheels and brakes and the second control module is in communication with the vehicle's rear wheels and brakes. The modules typically communicate with one another and with at least one user interface over a network communications link such as a J1939 serial data bus. Additional features and aspects of the present invention will become apparent to those of ordinary skill in the art upon reading and understanding the following detailed description of the preferred embodiments.
The accompanying drawings, which are incorporated into and form a part of the specification, schematically illustrate one or more exemplary embodiments of the invention and, together with the general description given above and detailed description of the preferred embodiments given below, serve to explain the principles of the invention.
The exemplary embodiment of the present invention shown in
For the purpose of characterizing the antilock brake system (ABS) architecture of the present invention,
The ECU 102 typically includes an on-board microprocessor that controls the overall function of antilock brake system 100 in accordance with preprogrammed commands and algorithms. Printed circuit boards and other similar devices may be used for or as part of the ECU. Although other configurations are possible, each modulator valve typically contains two solenoids and regulates the air pressure to front brake chambers 120, 122 and rear brake chambers 124, 126 during ABS activity. When not receiving commands from the ECU, a modulator valve generally allows air to flow freely and has little or no effect on the brake pressure. In response to signal input, the ECU commands the modulator valve to either change the air pressure to the brake chamber, or hold the existing pressure. However, a modulator valve does not typically apply the brakes automatically, or increase the brake application pressure above the level applied by a driver using service brake valve 140 to apply the brakes. Although other configurations are possible, each wheel speed sensor typically includes an exciter (see 112a), a pickup see (112b), and associated wiring and mounting equipment. The exciter, also known as a sensor ring, tooth wheel, or tone ring is a ring with notched teeth. The pickup is commonly referred to as “the sensor” and contains a wire coil/magnet assembly, which generates pulses of electricity as the teeth of the exciter pass in front of it. The ECU uses the electrical pulses to determine the wheels speeds and rates of acceleration and deceleration. ABS configuration is typically defined by the arrangement and number of sensors and modulator valves incorporated into the system. The most common configurations are: four sensors/four modulators (4S/4M), six sensors/four modulators (6S/4M), and six sensors/six modulators (6S/6M). Common configurations for trailers are 2S/1M, 2S/2M, 4S/2M and 4S/3M.
In operation, the wheel speed sensors monitor the speed of front wheels 128, 130 and rear wheels 132, 134 and send electrical pulses to ECU 102 at a rate proportional to the wheel speed. When the pulse rates indicate impending wheel lockup, the ECU signals one of more of the modulator valves to reduce and/or hold the brake application pressure to the appropriate wheel or wheels. The ECU then adjusts pressure and attempts to apply maximum braking force without risking wheel lockup. In the exemplary system of
Most ABS systems have self-diagnostic capability to assure proper operation of the system. Typically, the ECU repeatedly monitors itself and if it detects a malfunction or failure, it will shut down the affected part of the system or even the entire system. On truck-tractors and single-unit or straight trucks, an ABS system may provide diagnostic information to technicians through the malfunction indicator lamp and/or an electronic diagnostic tool, which plugs into an on-board diagnostic connector. The connector is typically located inside the tractor cab just underneath the left end of the instrument panel. It is usually the same connector that's used to troubleshoot electronic engines. As shown in
In one embodiment of the present invention (not shown in the Figures), the modulator controllers are integrated “mechantronic” units that include, within a single housing or enclosure, a printed circuit board (PCB) in communication with the wheel sensors and also in communication with a valve assembly. The valve assembly further includes at least one solenoid valve and at least one modulator valve in communication with the solenoid. The modulator valve may include relay or other pneumatic valve functionality. This embodiment includes at least one communication connection, at least one power connection, at least one sensor input, at least one pneumatic brake port, at least one exhaust port, and at least one connection between the PCB and the solenoids. A cover may be provided to seal the enclosure and protect the PCB and other components. In another embodiment of the modulator controllers (not shown in the Figures), each modulator controller is a non-integrated assembly of separate parts, i.e., a PCB, a solenoid sub-assembly, and a modulator valve sub-assembly. Functionally, this embodiment is similar or identical to the mechatronic version and includes most or all of the same connections, inputs, and ports.
In the exemplary embodiment of system 200 (see
As shown in
In operation, the ABS system functions substantially in the same manner as the system of
In general, the in-vehicle networking aspect of the present invention may be used for transferring data among distributed electronic modules via a serial data bus. Without this serial networking, inter-module communication typically requires dedicated, point-to-point wiring resulting in bulky, expensive, complex, and difficult to install wiring harnesses. Utilizing a serial data bus reduces the number of wires by combining the signals on a single wire through time division multiplexing. Information is sent to individual control modules that control each function, such as the anti-lock braking aspect of this invention.
In the exemplary embodiment shown in
While the present invention has been illustrated by the description of exemplary embodiments thereof, and while the embodiments have been described in certain detail, it is not the intention of the applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Therefore, the invention in its broader aspects is not limited to any of the specific details, representative apparatus and methods, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of the applicant's general inventive concept.
