Patent ID: 12187248

DETAILED DESCRIPTION

The example embodiments described herein provide an apparatus and method for use in controlling release of a parking brake of a parking brake system of an associated vehicle. The exemplary embodiments may utilize a series of electrically controlled valves that are in turn used to operate at least one pneumatic latching valve to apply or release a vehicle's parking brakes. Thus, the logic of the system and method of the present disclosure includes both electrical and pneumatic components. The electrically controlled valves, which in the exemplary embodiments may be solenoid valves for example, that are used only to induce a “change of state” in the vehicle's parking brakes, as described below. With reference to the Figures in general, a series of small capital letters are used to designate the ports of the various valves included in the system of the present invention. The letter “S” refers to “supply,” the letter “C” refers to “control,” the letter “D” refers to “delivery,” and the letter “E,” refers to “exhaust.” In the context of this invention, control air is used as a pneumatic signal that opens or closes a latching valve, while supply air is used to apply or release a terminal device such as a spring brake.

To distinguish the characteristics of the example embodiments from conventional pneumatic systems,FIG.1provides a partial schematic representation of an air brake system100that utilizes pneumatic circuits exclusively. InFIG.1, all lines depicted in the drawing are pneumatic lines with no electrical circuits being present. The dashboard module110includes five (5) pneumatic lines of ⅜ inch diameter and several feet in length. These components are present in the vehicle's cab and traverse the firewall between the cab and the exterior portion of the vehicle.

Primary reservoir air reservoir120and secondary air reservoir122supply pressurized air to the parking control valve unit112by way of supply lines120aand122a. Dash valve114represents the “yellow button” as it is referred to by those skilled in the art, and includes a combination park pneumatic push-pull plunger. Dash valve116represents the “red button” as it is referred to by those skilled in the art, and includes a trailer park control and air supply pneumatic push-pull plunger. The pneumatic logic present in this system enables buttons114and116to “pop” out automatically in the event the air reservoirs fail and fall below a prescribed pressure, such as, for example, about 40 psi for valve116(red) and about 20 psi for valve114(yellow).

Delivery line130asupplies pressurized air to spring brake190, while trailer supply line130bsupplies pressurized air to tractor protection module140and tractor protection valve170. By way of primary delivery line150aor secondary delivery line150b, foot brake valve150delivers pressurized air to valve170directly or through double check valve163. Likewise, trailer control valve160delivers pressurized air to valve170by way of delivery lines160aand162. Tractor protection valve170may include a service line quick release valve and supply line quick release valve and delivers pressurized air to trailer supply line172and trailer service line174as well as stop light switch180by way of delivery line180a.

With reference toFIG.2, an exemplary embodiment of an electro-pneumatic latching valve system1is shown in schematic form. As shown, the electro-pneumatic latching valve system1includes an electronic parking brake (EPB) control apparatus10for controlling application and/or release of a parking brake of a parking brake system of an associated vehicle. The electro-pneumatic latching valve system1further includes a first electric control valve18, a second electric control valve26, and a pneumatic latching valve40. A terminal device50, and an air reservoir60are also included in the exemplary embodiment. The two operational modes of the electric valves which may be solenoid valves are null or closed, and energized or delivery. The pneumatically latching valve possesses the same two operational modes although its input is pneumatic pressure, not solenoid current. The description of the exemplary embodiment refers to the electric control valves as solenoid valves; however, other electrically controllable valves or pneumatic valves may be used to control the operation of the pneumatically latching valve including, but not limited to piezoelectric valves and micro machine valves.

InFIG.2, a series of electrical lines connects the switch unit to the electric valves, and a plurality of pneumatic lines connects the air reservoir to the electric valves, the latching valve, and the terminal device. Pressurized air is delivered from reservoir60to the supply ports of valves18and26(see arrows B and F) and to the supply port of pneumatic latching valve40(see arrow D). This “black air” remains deadheaded at these ports until the operator of the vehicle actuates one of the switches in the apparatus10. Although not shown with particularity inFIG.2, an electronic control unit (ECU)70(FIG.5) in the form of a printed circuit board or similar device may be placed within the apparatus10or in-line or between the apparatus10and the solenoid assemblies for the purposes of integrating additional functionality into the system.

In the exemplary embodiment shown in the Figures, terminal device50is a spring brake actuator that utilizes pressurized air to apply or release the parking brakes of a vehicle. With reference toFIG.2, if the operator desires to release, i.e., deactivate, the parking brakes, release switch14is actuated. Upon actuation of the release switch and under the supervision and control of parking brake control logic executed in the apparatus in accordance with the example embodiments to be described in greater detail herein, electric current travels from release switch14to release valve20(see arrow A). In response to the electrical signal received at release valve20, the delivery port of solenoid valve22is opened and pressurized air is delivered to the top control port of pneumatic latching valve40(see arrow C). Upon receiving this pneumatic signal, the piston within latching valve40moves from its closed state and the supply port of valve40is opened allowing pressurized air to pass through to the delivery port of the valve and into the spring brake, i.e., terminal device50(see arrow D). The pressurized air forces the spring within the brake chamber to retract and the vehicle's parking brakes are released allowing the vehicle to move.

When the operator releases switch14and under the supervision and control of parking brake control logic executed in the apparatus in accordance with the example embodiments to be described in greater detail herein, valve22closes and airflow through the valve ceases. Pressurized air that was delivered to the control port of pneumatic latching valve40is exhausted through the exhaust port of solenoid valve22. Although solenoid valve22is closed, and there is no air passing though the valve, the parking brakes of the vehicle remain released because pressurized supply air is still being delivered from reservoir60to the spring brake. Thus, valve40is referred to as a pneumatic “latching” valve because continuous current to the release valve is not required for the system to maintain continuous air flow to the terminal device. This aspect is particularly advantageous over prior art systems because loss of electrical power or connectivity to the parking brake system does not automatically result in the application of the vehicle's parking brakes.

Again with reference toFIG.2if the operator desires to apply, i.e., activate, the parking brakes, apply switch16is actuated. Upon actuation of the apply switch16and under the supervision and control of parking brake control logic executed in the apparatus in accordance with the example embodiments to be described in greater detail herein, electric current travels from apply switch16to apply valve28(see arrow E). In response to the electrical signal received at apply valve28, the delivery port of solenoid valve30is opened and pressurized air is delivered to the bottom control port of pneumatic latching valve40(see arrow G). Upon receiving this pneumatic signal, the piston within valve40returns to its closed state, terminating the flow of pressurized air through the valve to the delivery port and into the spring brake, i.e., terminal device50. The exhaust port of pneumatic latching valve40then opens and air from the spring brake actuator is exhausted to the atmosphere (see arrows H and I). Exhausting the pressurized air in this manner causes the spring within the brake chamber to return to its normal bias and the vehicle's parking brakes are applied.

When the operator releases switch16and under the supervision and control of parking brake control logic executed in the apparatus in accordance with the example embodiments to be described in greater detail herein, valve30closes and airflow through the valve ceases. Pressurized air that was delivered to the control port of pneumatic latching valve40is exhausted through the exhaust port of solenoid valve30. Although solenoid valve30is closed, and there is no air passing though the valve, the parking brakes of the vehicle remain applied because no pressurized air is being delivered from reservoir60to the spring brake. As stated above, valve40is referred to as a pneumatic latching valve because continuous current to the apply solenoid is not required for the system to prevent air flow to the terminal system device. Again, loss of electrical power or connectivity to the parking brake system does not automatically result in a change of state in the vehicle's parking brakes.

The electro-pneumatic latching valve system1may be incorporated into larger, more complex tractor/trailer brake system.FIG.3provides a partial schematic of an exemplary embodiment of brake system100. This system comprises two basic modules or subsystems: the an electronic parking brake (EPB) control apparatus10and a brake control subsystem245, wherein the an electronic parking brake (EPB) control apparatus10includes an electronic control unit (ECU)70(FIG.5) in the form of a printed circuit board or similar device that may be placed within the apparatus10or disposed in-line or between the apparatus10and the solenoid assemblies for the purposes of integrating additional functionality into the system. Brake control subsystem245further includes a remote module250and tractor protection module270. The components of the electronic parking brake (EPB) control apparatus10are typically mounted on or within the dashboard of the vehicle, while remote module250is typically mounted to an exterior surface of the cab of the vehicle and includes subcomponents that are both internal and external to the cab. The tractor protection module270also typically includes subcomponents that are both internal to and external to the cab of the vehicle.

As shown inFIG.3, the electronic parking brake (EPB) control apparatus10comprises tractor and combination park electrical switch unit (the “yellow button”)212and trailer park and supply electrical switch unit (the “red button”)214. In the exemplary embodiment, these buttons are 2-position, momentary on-off-on, press-pull hinged toggle-type devices that provide the operator with an interface to the vehicle's parking system, and serve as the input devices, which drives electric valves252,254,256, and258, which in the exemplary embodiment are solenoid valves. These buttons may be backlit214a,216afor visibility and may include a status indicator in the form of variable light intensity or an LED. The buttons are lit based either on input from pressure switches or on valve position, which typically includes contacting or non-contacting indicator switches that indicate whether the park brakes are applied or released.

A button coupling diode functionality216is provided for example in software logic of the electronic control system70between assemblies212and214and couples the function of the trailer and tractor components of the system. This coupling can be performed logically within the software logic of the electronic control system70or by an equivalent device such as an electrical driver circuit that emulates the logic of a diode or may be implemented pneumatically with a check valve placed between the park sides of the yellow and red valves. Typically, the coupling logic utilized by a diode function or other electronics is designed such that operating the park function of the yellow button unit automatically operates the park function of the red button unit. This functionality can be characterized as a “single-button park feature.” The electro-pneumatic system of the present invention functions such that if the two status lights on the valve unit are extinguished, then a single pull of the yellow button will pass current to both the yellow and red park solenoids, thus lighting both the red and yellow buttons once the parking action is complete.

In the example embodiment shown inFIG.3, tractor brake circuit213connects yellow button212to solenoid valve256and solenoid valve258and provides an electrical pathway for activating these two solenoids. Likewise, trailer brake circuit215connects red button214to solenoid valve252and solenoid valve254and provides an electrical pathway for activating these two solenoids. It should be noted that in the embodiment that includes an electronic control unit circuits213and215either connect the buttons to the electronic control unit or connect the electronic control unit to the solenoids.

The power for operating circuits213and215is provided by a power source230, which is typically a 12V battery, and a capacitor232that is in electrical communication with both the electronic parking brake (EPB) control apparatus10and brake control subsystem245. In the event of electrical power loss, capacitor232provides energy for at least one additional parking application; thus, the operator may still park the vehicle despite the loss of electrical power to the brake system. A diode or other isolation circuit and/or logical function may be employed to ensure that the capacitor's charge is preserved only for the parking system, and not discharged through the remainder of the vehicle electrical system. In alternate embodiments, a simple capacitor, a complex capacitive circuit, or other suitable means provides backup power. In general, power supply230and capacitor232comprise primary and secondary power supplies that provide the system with certain protections, conditioning, and backup emergency parking capability.

The embodiment shown in logical form inFIG.3aincludes a printed circuit board that serves as the electronic parking brake (EPB) control apparatus10for the brake system. The printed circuit board can be placed in the vehicle's dash or it may be attached to the parking control subsystem. In one embodiment, the brake control subsystem245is in an enclosure mounted on the back-of-cab wall, and printed circuit board211is mounted on, attached to, or integrated with the parking control subsystem. The printed circuit board may utilize dash buttons with hall effect sensors, and most or all of the support components or modules for the button unit, i.e., buttons212and214, hall sensors, LEDs, LED intensity selection221, LED drivers222, feedback error detection223, feedback sensors224and225, solenoid drivers217, backup power supply232, and interlock support/interface223, is integrated into the printed circuit board. The printed circuit board may also include a microprocessor5that includes an input handler module219and a logic circuit or module218.

It is to be appreciated that a number of variations are possible with the system described herein. For example: (i) the solenoids may be assembled as a manifold at the vehicle's firewall such that all electrical connections are on the cab-side of the firewall and all the pneumatic connections are on the engine-side of the firewall; (ii) a time-delay circuit or strategy may be employed such that risk of unintended actuation of the parking brakes is reduced; (iii) the actuators can be any working switch logic, either driver-manipulated (push-pull buttons, flippers, sliders, dials) or coupled to another system (transmission shifter “park” position, for example); (iv) the system can receive additional logic, information, or control from an ABS ECU with the authority to control the brake system by a dedicated network protocol such as CAN; (v) the system may employ a dedicated ECU or the system may receive only advisory information, not command information, from an engine or chassis ECU other than an ABS ECU; (vi) the solenoid control may also be replaced by pneumatic pilot control using pneumatic valves that would emulate the operation of the 3-way/2-position, normally closed solenoids described above, e.g., the self-returning TH-3 (Bendix).

The example embodiment also provides a means for allowing safety interlocks to be integrated into a vehicle's brake system as simple electrical switch inputs. In general, the safety interlocks of the present invention (i) prohibit parking brake release based on information obtained from devices around a vehicle that indicates a safety concern regarding movement of the vehicle; and/or (ii) force the vehicle into park based on information obtained from devices around a vehicle that indicates the driver, upon exiting the vehicle, has forgotten to park the vehicle; and/or (iii) provide a bypass for causing the parking brake of the vehicle to release even if the standard set of release interlocks are not satisfied at the DECU; and/or (iv) provide an override for causing the parking brake of the vehicle to release even if the standard set of release interlocks are not satisfied at the DECU. In the exemplary embodiment, safety interlock and theft deterrence are achieved simply by connecting existing vehicle switches (ignition key, brake light switch, door switch, safety belt switch, etc.) to an optional printed circuit board. The printed circuit board, if included, may be placed in an enclosure and may be located in the dash, integrated with existing buttons, or located on the in-the-cab side of the parking control subsystem.

In accordance with an embodiment, the electronic control system70of the electronic parking brake (EPB) control apparatus10includes a processor76that executes parking brake control logic74to selectively generate a parking brake release (PBR) signal to release the parking brake based on the electronic control system70receiving fully all of a set of predetermined PBR interlock standard satisfaction signals. In this way, the vehicle parking brake may be held in an engaged state until a particular set of regular or otherwise standard release interlocks are satisfied such as, for example, the driver must be buckled, the brake pedal must be depressed, and the door must be closed before the parking brake is permitted to release in reply to actuation by the driver of one or more of the dash mounted electronic switches.

In accordance with an embodiment, the PBR interlock standard satisfaction signals include: i) operator PBR interlock standard satisfaction request signals; and ii) vehicle PBR standard operating condition signals.

The operator PBR interlock standard satisfaction request signals are in the example representative of a PBR interlock standard satisfaction request received from the operator of the associated vehicle. The PBR interlock standard satisfaction request received from the operator of the associated vehicle may include, for example, a service brake pedal actuated signal representative of a service brake pedal being actuated by the operator of the associated vehicle, and/or an instrument panel switch signal representative of a switch on an instrument panel of the associated vehicle being actuated by the operator.

The vehicle PBR standard operating condition signals are in the example representative of one or more operating conditions of the associated vehicle. The vehicle PBR standard operating condition signals may include, for example, one or more of an ignition ON signal representative of an ignition of the associated vehicle being in an active state, an engine running signal represented of an operating condition of an engine of the associated vehicle, a transmission engaged signal representative of a shift protocol of a transmission of the associated vehicle being competed, and vehicle operational readiness signals representative of a readiness of operation of the associated vehicle by the operator.

In accordance with a further embodiment, the processor of the electronic control system70of the electronic parking brake (EPB) control apparatus10executes the parking brake control logic to selectively generate a parking brake release (PBR) signal to release the parking brake based on the electronic control system70receiving a set of predetermined PBR interlock override signals in an absence of receiving fully all of the set of predetermined PBR interlock standard satisfaction signals. In this way, the parking brake of the vehicle may be released even if the particular set of regular or otherwise standard release interlocks are unsatisfied such as, for example, as may occur when one or more of the devices providing the particular set of release interlock input signals to the DECU fail or are corrupted thereby preventing the transition of the parking brake from a set or engaged state to a released or disengaged state. By way of example, a switch that generates a signal representative of a door of the vehicle being closed such as for example a school bus door switch, may malfunction thereby causing the particular set of release interlocks to remain unsatisfied at the DECU, even though the door may be physically closed in fact. The electronic parking brake (EPB) control apparatus10of the example embodiments herein therefore provide an override of the standard or regular PBR protocol for causing the parking brake of the vehicle to release even if the standard set of routine or otherwise standard release interlocks are not satisfied at the DECU. One useful example of this function is to move a school bus having such a malfunctioning switch or the like from an entranceway of a tightly packed bus parking lot to thereby provide an egress pathway to other busses in the lot so that they may attend to their respective routes.

In accordance with an embodiment, the PBR interlock override signals include: i) operator PBR interlock override request signals; and ii) Vehicle PBR override operating condition signals.

The operator PBR interlock override request signals are representative of a PBR interlock override request received from an operator of the associated vehicle. In the example embodiment, the operator PBR interlock override request signals representative of the PBR interlock override request include an accelerator pedal actuated signal representative of an accelerator pedal being actuated by the operator of the associated vehicle, and an instrument panel switch signal representative of a switch on an instrument panel of the associated vehicle being actuated by the operator.

The vehicle PBR override operating condition signals are representative of one or more operating conditions of the associated vehicle disposed in a PBR interlock override posture by the operator. In the example embodiment, the vehicle PBR override operating condition signals are representative of one or more operating conditions of the associated vehicle include an ignition ON signal representative of an ignition of the associated vehicle being in an active state, an engine running signal represented of an operating condition of an engine of the associated vehicle, and a transmission engaged signal representative of a shift protocol of a transmission of the associated vehicle being competed.

In particular and in accordance with an example embodiment and as shown in Table I below, the PBR interlock standard satisfaction signals include: i) operator PBR interlock standard satisfaction request signals; and ii) vehicle PBR standard operating condition signals.

TABLE II. PBR interlock standard satisfaction signalsA. operator PBR interlock standard satisfaction request signals -(representative of a PBR interlock standard satisfaction request receivedfrom the operator of the associated vehicle)1. service brake pedal actuated signal - (representative of aservice brake pedal being actuated by the operator of theassociated vehicle)2. instrument panel switch signal - (representative of a switchon an instrument panel of the associated vehicle being actuated bythe operator)B. vehicle PBR standard operating condition signals - (representativeof one or more operating conditions of the associated vehicle)1. ignition ON signal - (representative of an ignition of theassociated vehicle being in an active state)2. engine running signal - (represented of an operating conditionof an engine of the associated vehicle)3. transmission engaged signal - (representative of a shiftprotocol of a transmission of the associated vehicle beingcompeted)4. vehicle operational readiness signals - (representative of areadiness of operation of the associated vehicle by the operator)

In particular and in accordance with an example embodiment and as shown in Table II below, the PBR interlock override signals include: i) operator PBR interlock override request signals; and ii) Vehicle PBR override operating condition signals.

TABLE IIII. PBR interlock override signalsA. Operator PBR interlock override request signals - (representativeof a PBR interlock override request received from an operator of theassociated vehicle)1. accelerator pedal actuated signal - (representative of anaccelerator pedal being actuated by the operator of the associatedvehicle)2. instrument panel switch signal - (representative of a switchon an instrument panel of the associated vehicle being actuatedby the operator)B. Vehicle PBR override operating condition signals - (representativeof one or more operating conditions of the associated vehicle disposedin a PBR interlock override posture by the operator)1. ignition ON signal - (representative of an ignition of theassociated vehicle being in an active state)2. engine running signal - (represented of an operating conditionof an engine of the associated vehicle)3. transmission engaged signal - (representative of a shiftprotocol of a transmission of the associated vehicle beingcompeted)

In addition to air brake systems, the electro-pneumatic valve system of the example embodiment is compatible with any number of pneumatic systems in which a change of state is not desirable should electric power to the system or its components be lost. For example, this electro-pneumatic valve system may be used with a variety of pneumatic lift devices, including, but not limited to, powered doors, axle shifters, wheel chair lifts, cherry pickers, and air suspension systems.

With continued reference toFIG.3a, an exemplary embodiment of remote module250further comprises a plurality of electric valves (e.g., solenoid valves), as well as two pneumatically latching valves. Although all four electric valves in the exemplary embodiment are basically identical, each solenoid performs a different function. These subcomponents may be mounted together within a single casting or molding. By way of example, each solenoid may be a 3-way/2-position normally closed solenoid valve that pilots the pneumatic latch valve from one state to another based on the operator's commands.

In the exemplary embodiment, “red” trailer supply valve252is situated above pneumatically latching trailer side valve260and “red” trailer park solenoid254is situated below valve260; however, these two solenoids may be packaged together in a single housing and may reside on top of or between the latching valves. This combination of solenoids and pneumatic latching valve comprise the portion of the system that pneumatically operates the braking system of the vehicle's trailer (seeFIG.3). Trailer supply line264exits pneumatically latching valve260and provides pressurized air to tractor protection module270by way of line264a. The trailer supply line feeds the trailer reservoirs and applies or releases the parking and/or emergency brakes.

“Yellow” tractor park release solenoid valve256is situated above pneumatically latching tractor side valve262and “yellow” tractor park apply solenoid valve258is situated below pneumatically latching valve262; however, these two solenoids may be packaged together in a single housing and may reside on top of or between the latching valves. In the exemplary embodiment, this combination of solenoids and pneumatically latching valve comprise the portion of the system that pneumatically operates spring brake298, which is located in the tractor portion of the vehicle. Spring brake298is supplied with pressurized air by tractor spring brake delivery line266.

In the embodiments shown inFIGS.3and4, each pneumatic latching valve is operated by solenoid-piloted air rather than the operator's palm. Current commercially available valves would normally include a “mushroom” button that is manipulated, i.e., pushed in and pulled out by the operator. Here the button has been removed, and the valves are “pushed in” or “pulled out” by pressurized control air from the electrically controlled valves. In the exemplary embodiment, each pneumatically latching valve “pops” automatically under a prescribed air pressure, such as, for example, about 40 psi for trailer brake actuator214and about 20 psi for tractor brake actuator212regardless of the state of the solenoids.

In the exemplary embodiment, this pressurized air is supplied to the system by primary air reservoir240and/or secondary air reservoir242. Primary supply line240a, which runs from primary air reservoir240, and secondary supply line242b, which runs from secondary air reservoir242both connect to double check valve243, which delivers the greater of the two input pressures. Dual air supply line244exits double check valve243and then branches into multiple supply lines that provide the solenoids and the pneumatically latching valves with pressurized control and supply air from supply line244. As shown inFIG.3, pneumatically latching valve260is supplied by supply line244aand pneumatically latching valve262is supplied by supply line244f. The solenoids are supplied by supply lines244band244d, which are further split into additional supply lines. Solenoid252is supplied by supply line244c, solenoid254is supplied by supply line244e, solenoid256is supplied by supply line244g, and solenoid258is supplied by supply line244h. A dual air gauge (not shown) may be added to system1to monitor the air pressure within the pneumatic latch valves, which are the primary outputs of the system.

As shown inFIG.3, an exemplary embodiment of tractor protection module270includes two double check valves and a service line shut-off valve. Primary and secondary air reservoirs240and242supply pressurized air to foot brake valve280, which is in communication with double check valve294by way of primary foot valve delivery line281aand secondary foot valve delivery line281b. Double check valve294is in communication with a stop light switch (SLS) and also with double check valve296by way of delivery line294a. Primary and secondary air reservoirs240and242also supply pressurized air to trailer control valve290, which is in communication with double check valve296by way of trailer control delivery line290a. Double check valve296is in communication with a stop light switch (SLS) and service line shut-off valve by way of delivery line296a, which delivers to valve297the greater of the air pressures received from foot brake valve280and trailer control valve290. Service line shut-off valve297delivers pressurized air to trailer service line297aand provides the tractor protection function by closing the trailer service line in the event that the tractor supply reservoirs have failed or the trailer is otherwise damaged. The trailer service line pressure is proportional to the braking being done by foot or by hand, and is used by the trailer to apply the proportional amount of service brakes for routine stopping of the vehicle.

As with the generic embodiment, when one or the other brake actuator control buttons (yellow and red buttons) is pushed in by the operator, electrical current flows to the solenoid valve located on top the pneumatic latching valve. The solenoid opens and delivers black or control air to the piston within the pneumatic latching valve. The pneumatically latching valve opens, delivering supply air to the terminal system component, e.g., the tractor spring brake. When the brake actuator is released, the top solenoid valve closes and air flow through the solenoid valve ceases, and air delivered to the top of the pneumatically latching valve is exhausted. However, the valve remains open and continues to deliver supply air to the spring brake. When a yellow or red button is pulled outward from the neutral position, the above-described process is reversed. Control air from the solenoid valve on the bottom of the pneumatically latching valve pushes the valve back to the closed position, thereby shutting off the air flow from supply to delivery, and exhausting pressurized air to atmosphere. Thus, as previously stated, even though the electrical power to the system may fail, the pneumatic latching valve remains in its most recent state, i.e., it does not automatically apply the parking brakes due to an electrical failure.

FIG.4provides a schematic representation of the EPB release system controller unit10as applied to an air brake system for a truck, bus, or non-towing vehicle. In this embodiment, brake system200′ includes a driver interface subsystem210′ and brake control subsystem245′. Brake control subsystem245′ further includes a remote module250′ and a spring brake298′. Driver interface system210′ comprises a single electrical switch212′ for energizing solenoids256′ and258′, which in turn controls the operation of pneumatic latching valve262′. Pressurized air is supplied by primary reservoir240′ and secondary reservoir242′ and travels through lines240a′ and242b′ to double check valve243′. Pressurized air is then delivered to the various system components by way of pneumatic lines244′,244b′,244j′,244f′,244g′, and266′.

FIG.5illustrates a parking brake apparatus500on a tractor for use with an air braked commercial vehicle. The parking brake apparatus500may be an electronic parking brake system. The parking brake system500includes a tractor park switch212. The tractor park switch212is located in or on the dash of the vehicle. The driver changes the state of the tractor park switch212to indicate that he wants to apply or release the parking brakes of the tractor. The tractor park switch212may be a three state electric switch. For example, the driver pulls out the tractor park switch212to indicate that he wants to apply the tractor parking brakes, the driver pushes in the tractor park switch212to indicate that he wants to release the tractor parking brakes and the driver leaves the tractor park switch212in a neutral state to indicate that he wants the tractor parking brakes to remain in the current state. The tractor park switch212transmits a signal indicative of the driver's request to either apply the parking brakes of the tractor or to release the parking brakes of the tractor.

The parking brake system500includes a trailer supply switch214. The trailer supply switch214is also located in the dash and generally proximate to the tractor park switch212. The driver changes the state of the trailer supply switch212to indicate that he wants to supply air to or evacuate air from the air supply system to the trailer, which also supplies air to the trailer parking brake system. The trailer supply switch214may be a three state electric switch. For example, the driver pulls out the trailer supply switch214to indicate that he wants to apply the trailer parking brakes, the driver pushes in the trailer supply switch214to indicate that he wants to supply air to the trailer to release the trailer parking brakes and the driver leaves the trailer supply switch214in the neutral state to indicate that he wants the trailer parking brakes to remain in the current state. The trailer supply switch214transmits a signal indicative of the driver's request to either apply the trailer parking brakes or release the parking brakes of the trailer.

The parking brake system500includes a tractor park device38. The tractor park device38may be an electropneumatic device that applies air to the tractor parking brake actuators in response to a control signal, thereby releasing the parking brakes, or exhausts air to the parking brake actuators in response to a control signal, thereby applying the parking brakes.

The parking brake system500includes a trailer supply device40. The trailer supply device40may be an electropneumatic device that permits supply air to be transmitted to the trailer in response to a control signal, thereby releasing the parking brakes, or exhausts air in response to a control signal, thereby applying the parking brakes. The trailer supply device40may also include a pressure sensor36located on the trailer supply device40or the pressure sensor36may be in pneumatic communication with the supply air to the trailer supply device40. The pressure sensor36measures the supply air pressure delivered to the trailer supply device40and transmits a signal indicative of the supply air pressure. The pressure sensor36may also be located on the tractor for measuring the supply air pressure delivered to the tractor supply device38and transmits a signal indicative of the supply air pressure.

The parking brake system500may also include a feedback device, such as display42, used by the driver to receive information regarding the state of the parking brake system10. The display42may be a lamp or other indicator in the dash. The display42may be a driver information system that collects and displays information about the parking brake system10as well as other systems on the vehicle.

The parking brake system500includes an apparatus10for controlling release of the parking brake of the parking brake system of an associated vehicle. The apparatus10receives signals from the tractor park switch212and the trailer supply switch214, as well as signals regarding the vehicle operating condition. The apparatus10controls the tractor park device38and the trailer air supply device40to change the parking brake status of the tractor and the trailer. The apparatus10may also include functionality to control the anti-lock braking system, the stability system or the engine system on the vehicle.

The apparatus10includes an electronic control system70. The electronic control system70includes a non-transient memory device72, parking brake control logic74stored in the non-transient memory device72, and a processor76operably coupled with the non-transient memory device72. The control logic74receives signals from the first input14, the second input16, the third input18and the pressure input20to control the parking brake state of the tractor and trailer through control signals transmitted to the first output22and the second output24. The control logic74may include volatile, non-volatile memory, solid state memory, flash memory, random-access memory (RAM), read-only memory (ROM), electronic erasable programmable read-only memory (EEPROM), variants of the foregoing memory types, combinations thereof, and/or any other type(s) of memory suitable for providing the described functionality and/or storing computer-executable instructions for execution by the control logic74.

The electronic control system70includes several inputs. A first input14receives a signal indicative of a request to park a tractor from the tractor park switch214. A second input16receives a signal indicative of a request to supply air to a trailer from the trailer supply switch212.

A third input18receives a signal indicative of the vehicle operating condition. The third input18may be a discrete input from a sensor on the vehicle or may be an input compatible with a vehicle serial communications bus34, such as SAE J1939. The third input18receives information about the vehicle operating condition such as vehicle speed, ambient temperature, inclination of the vehicle, temperature of the trailer brakes and foot brake valve actuation.

The electronic control system70may include a pressure input20for receiving a trailer supply pressure signal from the pressure sensor36. Alternatively, a trailer supply pressure value may be received via the serial communications bus34.

The electronic control system70includes several outputs. A first output22transmits a control signal to the tractor parking brake device38. The control signal will place the tractor parking brake device38in either a supply air mode or an exhaust air mode. A second output24transmits a control signal to the trailer supply device40. The control signal will place the trailer supply device40in either a supply air mode or an exhaust air mode. The electronic control system70may include a third output26for transmitting a signal to the display42.

FIG.6illustrates a switch module80having tractor park switch212and trailer supply switch214. The switch module80may be installed in a dash of an associated vehicle. For this switch module80, the tractor park switch212has a handle end that is capable of being pulled out by a driver when the driver wants to actuate the tractor park brakes. The trailer supply switch214also includes a handle portion. The handles are marked, colored or shaped to differentiate the trailer supply switch214from the tractor park switch212.

The tractor park switch212and trailer supply switch214may be three state switches. For example, the tractor park switch212can be moved into a first state, which is a pushed in position, a second state, which is a pulled out position and a third state, which is a neutral position. The tractor park switch212is shown in the neutral position inFIG.6. In order to release the tractor parking brakes, the driver actuates the tractor park switch212by pushing in on the handle portion. Pushing in on the handle portion transmits a signal to the electronic control system70at input14indicating that the handle portion has been pushed in and the driver desires to release the tractor parking brakes. The handle portion may automatically return to the neutral position when the driver removes the force used to push in the handle portion. Alternatively, the handle portion may remain in the pushed in position so the driver has a visual indication that the tractor park brakes are released. The handle portion will remain in the pushed in position until the driver moves the handle portion to the pulled out position.

The driver actuates the tractor park switch30by pulling out on the handle54. Pulling out on the handle transmits a signal to the electronic control system70at the input14indicating that the handle54has been pulled out and the driver desires to apply the tractor parking brakes. The handle54may automatically return to the neutral position when the driver removes the force used to pull out the handle54. Alternatively, the handle54may remain in the pulled out position so the driver has a visual indication that the tractor park brakes are applied.

The trailer supply switch214can moved into a first state, which is a pushed in position, a second state, which is a pulled out position and a third state, which is a neutral position. The trailer supply switch214is shown in the pulled out position inFIG.6. The driver will pull out on the handle when he desires to release air from the trailer supply and thereby park the trailer. Pulling out on the handle transmits a signal to the electronic control system70at input16indicating that the handle has been pulled out and the driver desires to release air from the trailer supply. The handle may automatically return to the neutral position when the driver removes the force used to pull out the handle. Alternatively, the handle may remain in the pulled out position so the driver has a visual indication that the trailer air supply is released. The handle will remain in the pulled out position until the driver moves the handle to the pushed in position.

The driver actuates the trailer supply switch214by pushing in the handle. Pushing in the handle transmits a signal to the electronic control system70at input16indicating that the handle has been pushed in and the driver desires to supply air to the trailer. The handle may automatically return to the neutral position when the driver removes the force used to push in the handle. Alternatively, the handle may remain in the pushed in position so the driver has a visual indication that the trailer air supply is applied.

Alternatively, tractor park switch30and the trailer supply switch214may be rocker switches having three positions. From a neutral position (e.g. the third state), a rocker switch for the tractor park switch30may be pushed near the top to an engage park brakes position (e.g., the second state), and pushed near the bottom to a disengage park brakes position (e.g., the first state). In another example, the tractor park switch212and the trailer supply switch214may be twistable. From a neutral position (e.g. the third state), a twistable switch for the tractor park switch212may be twisted to the right to an engage park brakes position (e.g. the second state), and twisted to the left to a disengage park brakes position (e.g., the first state).

In switch module80, the application of the trailer parking brakes at the same time as application of the tractor parking brakes may not be implemented in every instance, as will be described further.

FIG.7is a flow chart showing a method700of releasing a parking brake of an associated vehicle in accordance with an example embodiment. With reference now to that Figure, the method includes storing parking brake control logic in a non-transient memory device of an electronic control system of an apparatus, and executing the parking brake control logic by a processor operatively coupled with the non-transient memory device to selectively generate a parking brake release (PBR) signal based on the electronic control system of the apparatus receiving a set of predetermined PBR interlock override signals in an absence of receiving fully all of a set of predetermined PBR interlock standard satisfaction signals, wherein receiving fully all of the set of predetermined PBR interlock standard satisfaction signals causes the processor executing the parking brake control logic to generate the PBR signal, wherein the set of predetermined PBR interlock override signals is different than the set of predetermined PBR interlock standard satisfaction signals, wherein the PBR signal is deliverable for use by the associated vehicle to effect the release of the parking brake of the parking brake system of the associated vehicle.

In the method, parking brake control logic is stored in step710in a non-transient memory device of an electronic control system of an apparatus.

In step720, the parking brake control logic is executed by a processor operatively coupled with the non-transient memory device to selectively generate a parking brake release (PBR) signal based on the electronic control system of the apparatus receiving a set of predetermined PBR interlock override signals in an absence of receiving fully all of a set of predetermined PBR interlock standard satisfaction signals, wherein the set of predetermined PBR interlock override signals is different than the set of predetermined PBR interlock standard satisfaction signals.

More particularly, it is determined in step730whether fully all of a set of predetermined PBR interlock standard satisfaction signals are received by the electronic control system of the apparatus.

In an absence of the electronic control system of the apparatus receiving fully all of the set of predetermined PBR interlock standard satisfaction signals at step730, the method700continues to step740where it is determined whether a set of predetermined PBR interlock override signals is received by the electronic control system in the absence of the electronic control system receiving fully all of a set of predetermined PBR interlock standard satisfaction signals.

If it is determined in step730that fully all of the set of predetermined PBR interlock standard satisfaction signals are received by the electronic control system of the apparatus, the processor executes the parking brake control logic in step750to generate the PBR signal. The PBR signal is deliverable for use by the associated vehicle to effect the release of the parking brake of the parking brake system of the associated vehicle.

If it is determined at step740that the set of predetermined PBR interlock override signals are received by the electronic control system of the apparatus in an absence of receiving fully all of a set of predetermined PBR interlock standard satisfaction signals in step730, the processor executes the parking brake control logic in step750to generate the PBR signal. The PBR signal is deliverable for use by the associated vehicle to effect the release of the parking brake of the parking brake system of the associated vehicle.

As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. Further, “comprises,” “includes,” and like phrases are intended to specify the presence of stated features, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and/or groups thereof.

While the present disclosure has been illustrated and described in detail in the drawings and foregoing description, such illustration and description is not restrictive in character, it being understood that illustrative embodiment(s) have been shown and described and that all changes and modifications that come within the spirit of the present disclosure are desired to be protected. Alternative embodiments of the present disclosure may not include all of the features described yet still benefit from at least some of the advantages of such features. Those of ordinary skill in the art may devise their own implementations that incorporate one or more of the features of the present disclosure and fall within the spirit and scope of the appended claims.