Patent Application
20080164106
The present teachings relate to electric braking systems and methods for utility vehicles.
Utility vehicles, such as maintenance vehicles, cargo vehicles, shuttle vehicles, and golf cars typically employ mechanically or hydraulically actuated type brake assemblies for providing braking functions. The most common types of brake assemblies for gas utility vehicles include drum brakes and disc brakes. Drum brakes consist of shoes that press against a spinning surface called a drum. Disc brakes consist of a caliper that squeezes brake pads against a rotor. Hydraulic fluid can be supplied to hydraulic actuators of either one of the aforementioned brake assemblies. Additionally, mechanical forces can be supplied to mechanical actuators of either one of the aforementioned brake assemblies.
Both hydraulic and mechanical brake assemblies can be found together on a utility vehicle, each providing different braking functions. For example a mechanical brake assembly may be coupled to a rear axle for providing parking brake functions while hydraulic brakes assemblies can be coupled to rear wheels for providing conventional braking functions. Implementing one or more mechanical or hydraulic brake assemblies or combination thereof in utility vehicles can require a considerable amount of cable to supply the mechanical force and/or fluid lines to supply the hydraulic fluid.
Electromechanical braking systems, also referred to as brake-by-wire, are now being employed by automobile companies to replace conventional hydraulic and mechanical braking systems. Electromechanical braking systems replace hydraulic or mechanical components with “dry” electrical components. This occurs by replacing the conventional actuators with electric motor driven units. A move to electronic control from hydraulic and/or mechanical eliminates many of the manufacturing, maintenance, and environmental concerns associated with hydraulic and mechanical systems of utility vehicles.
Accordingly, a method of providing electric braking for a utility vehicle is provided. The method includes: providing an electric brake assembly including a rotor that is coupled to a rear axle shaft of the utility vehicle, an electric caliper that supplies stopping force to the rotor, and a spring that is pre-loaded to provide an alternative stopping force to the rotor; determining an electrical braking signal based on the brake position signal generated from a brake position sensor coupled to a brake pedal of the utility vehicle; and controlling operation of the electric caliper based on the electrical braking signal.
In other features, an electric braking system for a utility vehicle is provided. The system includes a rotor coupled to a rear axle of the utility vehicle. A caliper is electrically controlled to provide stopping force to the rotor. A spring is pre-loaded to actuate the caliper when additional stopping force is needed. A controller controls the activation of the caliper by generating an electrical braking signal to control operation of the caliper based on a brake position signal generated from a brake pedal position sensor.
Further areas of applicability of the present teachings will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present teachings.
The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present teachings in any way.
The following description of various embodiments is merely exemplary in nature and is in no way intended to limit the present teachings, application, or uses.
A controller 22 controls engine 12 based on an accelerator signal 24 received from an accelerator pedal assembly 26. Controller 22 controls electromechanical brakes 28A and 28B mounted to rear wheels 18A and 18B respectively based on a brake signal 30 received from a brake pedal assembly 32. Brake pedal assembly 32 includes a brake pedal 38 and a brake pedal position sensor 40. Brake pedal position sensor 40 generates brake signal 30 based on a sensed position of brake pedal 38. Accelerator pedal assembly 26 includes an accelerator pedal position sensor 34 and an accelerator pedal 36. Accelerator pedal position sensor 34 generates accelerator signal 24 based on a sensed position of accelerator pedal 36.
As can be appreciated, controller 22 may be any known microprocessor or controller known in the art. In an exemplary embodiment, controller 22 is a microprocessor having read only memory (ROM), random access memory (RAM), and a central processing unit (CPU). Controller 22 may include any number of control modules that provide the functionality for controlling electromechanical brakes 28A and 28B of utility vehicle 10 as will be described below. In various other embodiments, controller 22 is an application specific integrated circuit (ASIC), an electronic circuit, a combinational logic circuit and/or other suitable components that provide the electric brake control functionality as described below.
With continued reference to
In an exemplary embodiment, the various brake control systems can be implemented as control modules that include algorithms that can be executed by a processor of controller 22 as shown in
More particularly, service brake control module 72 determines a desired service brake electrical signal 82 based on a position of brake pedal 38 indicated by brake signal 30. Desired service brake electrical signal 82, when generated by brake signal generator module 92 as electrical signal 58, controls the activation of electromechanical brake 28A.
Antilock brake control module 74 determines a desired ABS electrical signal 84 when a slip of one or more wheels 20A, 20B, 18A and 18B of
Hill hold brake control module 76 determines a desired hill hold electrical signal 86 when brake signal 30 indicates that brake pedal 38 of
Parking brake control module 78 determines a desired parking brake electrical signal 88 based on various vehicle data signals 70 such as a parking brake switch signal indicating to turn on a parking brake function of electromechanical brake 28A. Desired parking brake electrical signal 88, when generated as electrical signal 58 by brake signal generator module 92, causes preloaded spring 60 of electromechanical brake 28A to actuate as discussed above, thereby providing sufficient force to bring utility vehicle 10 to an abrupt stop or to maintain utility vehicle 10 in a stopped position. In an exemplary embodiment, actual electrical signal 58 corresponding to desired parking brake electrical signal 88 may be zero volts or no signal at all so as to actuate spring 60 of electromechanical brake 28A.
Emergency brake control module 80 determines a desired emergency brake electrical signal 90 based on various vehicle data signals 70 such as an emergency shut-off switch signal indicating to actuate an emergency brake function of electromechanical brake 28A. Desired emergency brake electrical signal 90 causes preloaded spring 60 of electromechanical brake 28A to actuate as discussed above thereby providing sufficient force to bring the vehicle to an abrupt stop. In an exemplary embodiment, actual electrical signal 58 corresponding to desired emergency brake electrical signal 90 may be zero volts or no signal at all so as to actuate spring 60 of electromechanical brake 28A.
Brake signal generator module 92 receives desired brake signals 82-90 and applies an arbitration strategy to determine and generate electrical signal 58 to electromechanical brake 28A. An exemplary strategy includes prioritizing desired brake signals 82-90 such that a desired signal with a higher priority is generated if two desired brake signals are received at or near the same time. As can be appreciated, brake signal generator module 92 can similarly generate one or more electrical signals 58 to other electromechanical brakes such as electromechanical brake 28B shown in
The description herein is merely exemplary in nature and, thus, variations that do not depart from the gist of that which is described are intended to be within the scope of the teachings. Such variations are not to be regarded as a departure from the spirit and scope of the teachings.
