Patent Application
20240190410
Today's heavy-duty commercial vehicles configured for towing (“tractors”) are normally designed with two isolated braking circuits providing control of a steer axle (or steer axle group) and a rear axle (or rear axle group). Protected and isolated supply and control air signals can be provided from both circuits to a towed vehicle (a “trailer”) to provide braking on the trailer.
The following embodiments generally relate to a tractor protection system and method. In one embodiment, a tractor protection system is provided comprising a tractor protection controller comprising: an output port configured to be coupled with a braking system of a trailer; an input port configured to be coupled with a reservoir of a tractor; a relay comprising a control port, a source port coupled with the input port, and a drain port coupled with the output port, wherein the relay is configured to selectively allow air to flow between the source port and the drain port in response to a pneumatic signal received at the control port; and a solenoid valve configured to selectively close to prevent a pneumatic signal from being applied to the control port. The tractor protection system also comprises a braking controller configured to cause the solenoid valve to close in response to determining that the output port is not in pneumatic communication with the braking system of the trailer.
In another embodiment, a method is provided that is performed in one or more processors of a tractor. The method comprises determining whether the tractor is pneumatically coupled with a trailer; and in response to determining that the tractor is not pneumatically coupled with the trailer, causing a component in the tractor to prevent control air from being supplied to the trailer.
In yet another embodiment, a system is provided comprising an electronic tractor protection module configured to selectively prevent air flow to a trailer gladhand; and means for causing the electronic tractor protection module to prevent air flow to the trailer gladhand in response to determining that the trailer is pneumatically disconnected from the trailer.
Other embodiments are possible, and each of the embodiments can be used alone or together in combination.
Turning now to the drawings,
The rear and front service reservoirs 110, 120 of the braking sub-system are configured to store pressurized air supplied by a compressor (not shown), and the pressurized air in these reservoirs 110, 120 is used to control various braking components on front and rear axles of the tractor to decelerate the tractor. In this embodiment, the rear service reservoir 110 is part of a braking circuit that provides pneumatic pressure to the braking components of the rear axle(s) of the tractor, and the front service reservoir 120 is part of a separate braking circuit that provides pneumatic pressure to the braking components of the front axle(s) of the tractor. Accordingly, the braking system of the tractor of this embodiment has two isolated braking circuits: one providing braking of the rear axle(s) and another providing braking of the front axle(s).
The rear and front service reservoirs 110, 120 are coupled with respective valves in the foot brake module 70 via air hoses (lines) or the like. The foot brake module 70 comprises a brake pedal (e.g., a suspended pedal, where the valve is mounted above the pedal, or a treadle, which pivots directly on the valve mounted below the treadle). Actuation of the brake pedal causes the two valves to open proportional to the amount of actuation of the brake pedal, which caused pneumatic pressure supplied from the rear and front reservoirs 110, 120 to be supplied out of outlet ports of the foot brake module 70 in proportion to the amount of actuation of the brake pedal. The outlet ports of the foot brake module 70 are coupled with service brake components (not shown) of the tractor.
The foot brake module 70 can also provide signals to the braking controller 102 that represent the amount of actuation of the brake pedal. For example, in one embodiment, the foot brake module 70 comprises one or more sensors that measure how much stroke a driver indicates by pressing the brake pedal and transmit electronic signals representing that displacement, which represents a driver brake demand, to the braking controller 102. In one embodiment, the foot brake module 70 contains two sensors, one that increments up and one that increments down as the brake pedal is pressed. These two opposing signals can be used as an error detection mechanism, as the braking controller 102 can detect an error if the two signals it receives from the foot brake module 70 are not opposing. Also, in one embodiment, the foot brake module 70 generates a signal even when the brake pedal is not pressed (such signal would represent zero braking). That way, if the braking controller 102 receives no signal whatsoever from the foot brake module 70, the braking controller 102 can assume there is a fault or error in the foot brake module 70 or communication channel (which, in one embodiment, can be a direct, point-to-point communication channel, such as a universal asynchronous receiver-transmitter (UART) link). It should be understood that any suitable implementation of a foot brake module can be used, and a foot brake module can contain more or different components than those described herein.
This braking sub-system is also used to control braking of the trailer towed by the tractor. In addition to applying pressurized air to the service brakes of the tractor, pressurized air from the foot brake module 70 is also sent to the trailer via gladhand 18 to provide a control signal to actuate brakes on the trailer. In this embodiment, gladhand 19 is used to supply pressurized air from the rear or front service reservoirs 110, 120 to the trailer, and that air is used to apply service braking in the trailer in response to pneumatic control signals received via gladhand 18. Pressurized air from gladhand 19 is also used to release the parking brakes of the trailer. In this embodiment, the trailer has spring brakes that place the trailer in a parked state in the absence of pressurized air. To un-park the vehicle, a driver can cause pressurized air to flow on the service line of gladhand 19, and that air is applied to the spring brakes in the trailer to un-park the trailer. For example, the dash control module 50 can comprise a push-pull button that, when pushed in, causes the park valve module 60 to open. (Another push-pull button on the dash control module 50 can cause the park valve module 60 to apply air to release the spring parking brakes in the tractor.) The park valve module 60 receives pressurize air from the rear and front service reservoirs 110, 120, and the greater pressure is applied from the park valve module 60 in response the push-pull button being pushed in. That air is sent, via gladhand 19, to the trailer to release the spring parking brakes. The park valve module 60 can also detect the pressure being supplied out of gladhand 19. If that pressure is not above a threshold pressure, the valve in the park valve module 60 closes, preventing supply air from being provided out of gladhand 19.
As mentioned above, in addition to un-parking the spring brakes of the trailer, the pressurized air on the service line can be used to actuate the service brakes of the trailer in response to a pneumatic control signal supplied on the control line to gladhand 18. In one embodiment, the pressurized air from gladhand 19 is used to fill reservoir(s) in the trailer, and the pneumatic control signal supplied on gladhand 18 causes air to flow from the reservoir(s) to the braking components on the trailer. As will be discussed below, the tractor protection controller 100 can be used to supply the pneumatic control signal to the trailer and can be used to prevent or control the venting control air when a trailer is not connector to the tractor. This is referred to herein as “tractor protection.”
As shown in
In the default state shown in
When electronically-controlled braking is not used, the solenoid valves 200, 210, 220 are in the state shown in
Whatever the source of the pressurized air, the presence of pressurized air at the control port of the relay 250 causes the relay 250 to open in proportion to the amount of pressurized air received. This causes air received at the source port of the relay 250 to flow out of the drain port of the relay 250, in proportion to the control signal, and out of port 22 of the tractor protection controller 100 to gladhand 18. Pressure sensors 230, 240 measure the pressure at the source and drain, respectively, of the relay 250. That information and related control signals can be communicated to/from the braking controller 102 via the shown pins.
A problem can occur if one or both of the gladhands 18, 19 are not pneumatically coupled with the trailer. This can occur, for example, when the tractor is being operated without a trailer (i.e., in bobtail mode), when the gladhands 18, 19 become disconnected from the trailer, or where there is a hole in the control or supply lines. In that situation, when the driver presses the brake pedal or when the braking controller 102 applies electronic braking, control air would flow out, e.g., of the gladhands 18, 19, into the atmosphere, eventually depleting the air in the rear and front service reservoirs 110, 120. This can result in an insufficient amount of pressurized air in the rear and front service reservoirs 110, 120 to apply service brakes in the tractor and/or cause the tractor or trailer to automatically park.
To address this situation, Federal Motor Vehicle Safety Standard (FMVSS) No. 121 requires a “tractor protection system.” To provide tractor protection on the service line, the park valve module 60 can be configured to output air to the service line only when a pressure on the service line exceeds a threshold that indicates that the trailer is connected, as discussed above. To provide tractor protection on the control line, a mechanical tractor protection value can be employed that uses the service line pressure to open the valve to allow control air to flow. So, if the trailer is present, the park valve module 60 would allow service line air to flow to the tractor protection value, causing it to open to allow the control line air to flow. Conversely, if the trailer is not present, the park valve module 60 would not allow service line air to flow to the tractor protection value, leaving the value in a closed state, which would prevent control line air to flow.
However, there may be disadvantages associated with using a mechanical tractor protection valve to provide tractor protection. For example, the mechanical tractor protection valve can be subject to various mechanical failures, such as the piston being stuck completely or partially open or closed. There can also be difficulties in installing the mechanical tractor protection valve properly.
To address these issues, in one embodiment, the braking controller 102 causes the tractor protection controller 100 to close the solenoid backup (BU) valve 200 when the braking controller 102 determines that the tractor is not pneumatically coupled with the trailer. Closing the solenoid backup (BU) valve 200 prevents air from the foot brake module 70 from reaching the control port of the relay 250 to open the relay 250, thus preventing air from the supply ports 11, 21 from flowing out of the output port 22 of the tractor protection controller 100. Also, because the braking controller 102 knows that the tractor is not pneumatically coupled with the trailer, the braking controller 102 knows not to send signals to the tractor protection controller 100 to cause the solenoid input and output valves (IV, OV) 210, 220 to open to achieve electronic braking.
In this example, because the default state of the solenoid backup (BU) valve 200 is closed, the braking controller 102 “causes” the solenoid backup (BU) valve 200 to close by not sending an electronic signal to cause it to open (or by removing the signal if the valve 200 is open). In other implementations, the solenoid backup (BU) valve 200 may have a default open state or no default state, in which case applying a signal, rather than refraining from applying a signal, would cause the solenoid backup (BU) valve 200 to close.
The braking controller 102 can use any suitable way to determine that the tractor is not pneumatically coupled with the trailer. For example, in one embodiment, the braking controller 102 can be notified by the park valve module 60 or a controller coupled with the park valve module 60 (collectively or individually referred to herein as a “parking controller”) that service air is not being supplied to the trailer. In operation, the park valve module 60 detects the pressure being supplied out of gladhand 19. If that pressure is not above a threshold pressure, the valve in the park valve module 60 closes, preventing supply air from being provided out of gladhand 19. In this situation, the parking controller can notify the braking controller 102 of this situation (e.g., via a controller area network (CAN)). (The driver can also be notified of this situation.) This would cause the braking controller 102 to determine that the tractor is not pneumatically coupled with the trailer.
As another example, the braking controller 102 can determine that the tractor is not pneumatically coupled with the trailer via the source pressure sensor 240 in the tractor protection controller 100. More specifically, if pressurized air is being vented out of one or both of the gladhands 18, 19, the source pressure into the tractor protection controller 100 would drop. By monitoring the reading of the source pressure sensor 230, the braking controller 102 can determine that the tractor is not pneumatically coupled with the trailer in response to the monitored pressure dropping below a threshold.
It should be understood that these are merely examples and that the braking controller 102 can use other ways (e.g., pneumatically, electrically, mechanically, etc.) to determine that the tractor is not pneumatically coupled with the trailer. Accordingly, the details presented herein should not be read into the claims unless expressly recited therein.
Turning again to the drawings,
It should be understood that all of the embodiments provided in this Detailed Description are merely examples and other implementations can be used. Accordingly, none of the components, architectures, or other details presented herein should be read into the claims unless expressly recited therein. Further, it should be understood that components shown or described as being “coupled with” (or “in communication with”) one another can be directly coupled with (or in communication with) one another or indirectly coupled with (in communication with) one another through one or more components, which may or may not be shown or described herein.
It is intended that the foregoing detailed description be understood as an illustration of selected forms that the invention can take and not as a definition of the invention. It is only the following claims, including all equivalents, which are intended to define the scope of the claimed invention. Accordingly, none of the components, architectures, or other details presented herein should be read into the claims unless expressly recited therein. Finally, it should be noted that any aspect of any of the embodiments described herein can be used alone or in combination with one another.
