Patent Application
20090082935
The present invention generally relates to the field of vehicles and, more specifically, to methods and systems for controlling braking of a trailer hitched to a vehicle.
A trailer brake controller (TBC) system of a vehicle controls braking output to brake units of a trailer that is hitched to the back of the vehicle. The braking output to the trailer brake units is generally reduced by the TBC when the vehicle speed is below a certain predetermined level during a braking event to improve the smoothness of the braking event. The reduction in braking output can result in longer stopping distances due to the reduction in braking output as the vehicle speed decreases. However, in certain situations, for example during a panic braking event, shorter stopping distances may be desired.
Accordingly, it is desired to provide systems for controlling braking of a trailer hitched to a vehicle that provide for shorter stopping distances under certain situations, such as a panic braking event. It is also desirable to provide methods for controlling braking of a trailer hitched to a vehicle that provide for shorter stopping distances under certain situations, such as a panic braking event. Furthermore, other desirable features and characteristics of the present invention will be apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.
In accordance with an exemplary embodiment of the present invention, a method for controlling braking of a trailer hitched to a vehicle with a braking control system during a braking event is provided. The method comprises the steps of determining a vehicle speed, measuring an amount of braking intent applied to the braking control system, determining a first level of braking output for the trailer, providing the first level of braking output to the trailer if the vehicle speed is greater than a first predetermined threshold, and providing a second level of braking output to the trailer if both of the following conditions are satisfied: the vehicle speed is less than the first predetermined threshold, and the amount of braking intent has not exceeded a second predetermined threshold during the braking event. The first level of braking output corresponds to a function of the amount of braking intent. The second level of braking output is less than the first level of braking output.
In accordance with another exemplary embodiment of the present invention, a program product for controlling braking of a trailer hitched to a vehicle with a braking control system during a braking event is provided. The program product comprises a program and a computer-readable signal-bearing media. The program is configured to at least facilitate determining a vehicle speed, measuring an amount of braking intent applied to the braking control system, determining a first level of braking output for the trailer, providing the first level of braking output to the trailer if the vehicle speed is greater than a first predetermined threshold, and providing a second level of braking output to the trailer if both of the following conditions are satisfied: the vehicle speed is less than the first predetermined threshold, and the amount of braking intent has not exceeded a second predetermined threshold during the braking event. The first level of braking output corresponds to a function of the amount of braking intent. The second level of braking output is less than the first level of braking output. The computer-readable signal-bearing media bears the program.
In accordance with a further exemplary embodiment of the present invention, a system for controlling braking of a trailer having a plurality of brake units and hitched to a vehicle having a braking control system during a braking event is provided. The system comprises a first sensing device, a second sensing device, and a brake controller. The first sensing device is configured to at least facilitate determining a vehicle speed. The second sensing device is configured to at least facilitate measuring an amount of braking intent applied to the braking control system. The brake controller is coupled to the first sensing device and the second sensing device, and is electronically coupled to the plurality of trailer brake units. The brake controller is configured to at least facilitate determining a first level of braking for the plurality of trailer brake units, causing the plurality of trailer brake units to apply the first level of braking if the vehicle speed is greater than a first predetermined threshold, and causing the plurality of trailer brake units to apply a second level of braking if both of the following conditions are satisfied: the vehicle speed is less than the first predetermined threshold, and the amount of braking intent has not exceeded a second predetermined threshold during the braking event. The first level of braking output corresponds to a function of the amount of braking intent. The second level of braking output is less than the first level of braking output.
The present invention will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and wherein:
The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description.
The brake pedal application sensor 108 and the braking intent sensing device 110 are coupled to the brake pedal 106. The brake pedal application sensor 108 senses whether an operator is currently applying force to the brake pedal 106, for example by sensing when an operator's foot is in contact with the brake pedal 106. In one exemplary embodiment, the brake pedal application sensor 108 activates a brake light activation switch when the vehicle operator is currently applying force to the brake pedal 106, although it will be appreciated that other types of brake pedal application sensors 108 may also be used.
The braking intent sensing device 110 senses one or more measures of braking intent by a driver of the vehicle 102. For example, in a preferred embodiment, the braking intent sensing device 110 senses braking pressure against the brake pedal 106. The braking intent sensing device 110 may include one or more pedal travel sensors, pedal force sensors, and/or other sensors, not depicted in
The braking control system 100 also comprises a vehicle speed sensing device 112 that senses a speed at which the vehicle 102 is traveling. In one exemplary embodiment, the vehicle speed sensing device 112 may include one or more sensors disposed in or around one or more non-depicted wheels of the vehicle 102. In other embodiments, the vehicle speed sensing device 112 may include one or more sensors disposed inside the vehicle 102. In yet other embodiments, the vehicle speed sensing device 112 may include a combination of sensors disposed in the vehicle 102 as well as in or around one or more wheels of the vehicle 102.
The brake controller 114 is coupled to the brake pedal application sensor 108, the braking intent sensing device 110 and the vehicle speed sensing device 112, as well as to brake units 116 of the trailer 104. The brake controller 114 receives a first input 118 from the brake pedal application sensor 108, namely brake pedal application data, a second input 120 from the braking intent sensing device 110, namely braking pressure data or another form of braking intent data, and a third input 122 from the vehicle speed sensing device 112, namely vehicle speed data. As described in more detail below, the brake controller 114 uses values from the first, second, and third inputs 118, 120, and 122 to perform various calculations, comparisons, and determinations, such as those described further below in connection with
In the depicted embodiment, the brake controller 114 includes a computer system 124 that includes a processor 126, a memory 128, a bus 130, an interface 133, and a storage device 134. The processor 126 performs the computation and control functions of the brake controller 114, and may comprise any type of processor or multiple processors, single integrated circuits such as a microprocessor, or any suitable number of integrated circuit devices and/or circuit boards working in cooperation to accomplish the functions of a processing unit. During operation, the processor 126 executes one or more programs 132 preferably stored within the memory 128 and, as such, controls the general operation of the computer system 124.
The memory 128 stores a program or programs 132 that executes one or more embodiments of a braking control process of the present invention, discussed in more detail below. The memory 128 can be any type of suitable memory. This would include the various types of dynamic random access memory (DRAM) such as SDRAM, the various types of static RAM (SRAM), and the various types of non-volatile memory (PROM, EPROM, and flash). It should be understood that the memory 128 may be a single type of memory component, or it may be composed of many different types of memory components. In addition, the memory 128 and the processor 126 may be distributed across several different computers that collectively comprise the computer system 124. For example, a portion of the memory 128 may reside on a computer within a particular apparatus or process, and another portion may reside on a remote computer.
The bus 130 serves to transmit programs, data, status and other information or signals between the various components of the computer system 124. The bus 130 can be any suitable physical or logical means of connecting computer systems and components. This includes, but is not limited to, direct hard-wired connections, fiber optics, infrared and wireless bus technologies.
The interface 133 allows communication to the computer system 124, for example from a system operator and/or another computer system, and can be implemented using any suitable method and apparatus. It can include one or more network interfaces to communicate to other systems or components, for example the brake pedal 106, one or more terminal interfaces to communicate with technicians, and one or more storage interfaces to connect to storage apparatuses such as the storage device 134.
The storage device 134 can be any suitable type of storage apparatus, including direct access storage devices such as hard disk drives, flash systems, floppy disk drives and optical disk drives. In one exemplary embodiment, the storage device 134 is a program product from which memory 128 can receive a program 132 that executes one or more embodiments of a braking control process of the present invention. As shown in
It will be appreciated that while this exemplary embodiment is described in the context of a fully functioning computer system, those skilled in the art will recognize that the mechanisms of the present invention are capable of being distributed as a program product in a variety of forms, and that the present invention applies equally regardless of the particular type of computer-readable signal bearing media used to carry out the distribution. Examples of signal bearing media include: recordable media such as floppy disks, hard drives, memory cards and optical disks (e.g., disk 135), and transmission media such as digital and analog communication links. It will similarly be appreciated that the brake controller 114 may also otherwise differ from the embodiment depicted in
The trailer brake units 116 are used to slow or stop the trailer 104. The trailer brake units 116 receive the brake commands from the brake controller 114, and are controlled thereby accordingly. The trailer brake units 116 can include any number of different types of devices that, upon receipt of brake commands, can apply the proper braking torque as received from the brake controller 114. For example, in an electro-hydraulic system, the trailer brake units 116 can comprise an actuator that can generate hydraulic pressure that can cause brake calipers to be applied to a brake disk to induce friction to stop a vehicle. Alternatively, in an electromechanical brake-by-wire system, the trailer brake units 116 can comprise a wheel torque-generating device that operates as a vehicle brake. The trailer brake units 116 can also be regenerative braking devices, in which case the trailer brake units 116, when applied, at least facilitate conversion of kinetic energy into electrical energy
As shown in
A functional braking output value is then determined (step 203), representing an amount of braking output for the trailer that is based at least in part on the braking pressure or other measure of braking intent determined in step 202. Specifically, the functional braking output value is an amount of braking output provided to the trailer brake units 116 of
Next, a determination is made as to whether a braking event is active (step 204). Specifically, a braking event is determined to be active if an operator is exerting pressure against the brake pedal 106. In a preferred embodiment, this determination is made by the processor 126 of
If it is determined that a braking event is not active, then the above-mentioned Heavy Braking Flag is set equal to zero (step 206) if previously changed from zero, as discussed more fully below, indicating that the braking intent has not exceeded the predetermined braking intent threshold (for example, in a preferred embodiment, that the braking pressure has not exceeded a predetermined braking pressure threshold). In a preferred embodiment, the Heavy Braking Flag is set equal to zero by the processor 126 of
Alternatively, if it is determined that a braking event is active, then a determination is made as to whether the vehicle speed is less than a predetermined vehicle speed threshold (step 210). The predetermined vehicle speed threshold represents a relatively low level of vehicle speed, below which it is generally desirable to have reduced braking output provided to the trailer brake units 116 under ordinary conditions. For example, at vehicle speeds below the predetermined vehicle speed threshold, a reduction of the braking output provided to the trailer brake units 116 can provide for a smoother braking experience. In one preferred embodiment, the predetermined vehicle speed threshold is approximately ten miles per hour. However, this may vary, for example depending on the type of vehicle 102 and the type of trailer 104 hitched thereto. In a preferred embodiment, the predetermined vehicle speed threshold is stored in the memory 128 of the computer system 124 of
If it is determined that the vehicle speed is greater than or equal to the predetermined vehicle speed threshold, then braking output is provided to the trailer brake units 116 in an amount equal to the functional braking output value, which is preferably at least substantially proportional to the braking pressure or other measure of braking intent (step 226). Alternatively, if it is determined that the vehicle speed is less than the predetermined vehicle speed threshold, then the process proceeds through a number of additional steps to determine the appropriate amount of braking output for the trailer brake units 116, beginning with a determination as to whether the vehicle is stopped (step 212). In a preferred embodiment, this determination is made by the processor 126 of
If it is determined that the vehicle is stopped, then the Heavy Braking Flag is set equal to zero (or remains at zero) (step 214), and an adjustment factor is determined (step 216) for use in calculating the amount of braking output to be provided to the trailer brake units 116. In a preferred embodiment, the adjustment factor is based at least in part upon the vehicle speed, for example through the use of a look-up table or calculation. Also in a preferred embodiment, the adjustment factor is determined at least in part by the processor 126 of
Alternatively, if it is determined that the vehicle is not stopped, then a determination is made as to whether the braking intent is greater than a predetermined braking intent threshold (step 220). For example, in a preferred embodiment, the determination is made as to whether braking pressure is greater than a predetermined braking pressure threshold. In this embodiment, the predetermined braking pressure threshold is representative of an amount of braking pressure that would indicate a sense of urgency in braking, for example, a panic braking event. In such an event, the stopping distance for the trailer should be minimized, as this would typically outweigh the desire for a smoother braking experience under such conditions. In a preferred embodiment, this determination is made by the processor 126 of
If it is determined that the braking intent is greater than the predetermined braking intent threshold, then the Heavy Braking Flag is set equal to one (step 222), which indicates that the braking intent has exceeded the predetermined braking intent threshold during the braking event (for example, in a preferred embodiment, that the braking pressure has exceeded a predetermined braking pressure threshold, in a preferred embodiment). In either event, the process proceeds with a determination as to whether the Heavy Braking Flag has been set during the braking event (step 224).
If it is determined that the Heavy Braking Flag has not been set to one, then the above-described adjustment factor is determined for calculating the amount of braking output to be provided to the trailer brake units 116 (step 216). As described above, in a preferred embodiment, the adjustment factor is determined by the processor 126 of
Alternatively, if it is determined that the Heavy Braking Flag has been set to one, then braking output is provided to the trailer brake units 116 in an amount equal to the functional braking output value, which is preferably at least substantially proportional to the braking intent (for example, braking pressure, in a preferred embodiment) (step 226). Specifically, under these conditions, minimizing the stopping distance of the trailer is of primary importance, and therefore the full functional braking output value is provided to the trailer brake units 116 even though the vehicle speed is less than the predetermined vehicle speed threshold.
Accordingly, in one exemplary embodiment of the trailer braking control process 200, there is no braking output provided to the trailer brake units 116 if there is no braking event (step 208). If there is a braking event, then braking output is preferably provided to the trailer brake units 116 in an amount that is at least substantially proportional to the braking pressure, or to some other measure of braking intent (step 226) until the vehicle speed drops below the predetermined vehicle speed threshold (as determined in step 210). Once the vehicle speed drops below the predetermined vehicle speed threshold, then the amount of braking output provided to the trailer brake units 116 is thereafter dependent on whether the braking intent has exceeded the predetermined braking intent threshold during the braking event (as determined in step 224). If the braking intent has not exceeded the predetermined braking intent threshold during the braking event, then a reduced braking output is provided to the trailer brake units 116 (step 218), to thereby provide a smoother braking experience. However, if the braking intent has exceeded the predetermined braking intent threshold during the braking event, then braking output preferably is provided to the trailer brake units 116 in an amount that is at least substantially proportional to the braking pressure or other measure of braking intent (step 226) to help minimize the stopping distance of the trailer under these circumstances.
The trailer braking control process 200 of
First,
Turning now to
However, once the braking pressure 304 exceeds the predetermined braking pressure threshold 308 at point 509 of
Accordingly, a system and method for controlling braking of a trailer hitched to a vehicle is provided. The system and method provide smoother braking of the trailer under certain conditions, such as when the vehicle is traveling relatively slowly and there is no panic braking situation. The system and method also provide for shorter stopping distances for the trailer under certain other conditions, such as when there is a panic braking event or another reason for minimizing the stopping distance of the trailer as compared with stopping distances provided by other systems and methods in similar situations.
While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing the exemplary embodiment or exemplary embodiments. It should be understood that various changes can be made in the function and arrangement of elements without departing from the scope of the invention as set forth in the appended claims and the legal equivalents thereof.
