FORM 2
THE PATENTS ACT, 1970
(39 OF 1970)
AND
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See Section 10; rule 13)
TITLE OF THE INVENTION “NON-RETURN VALVE-BASED VEHICLE BRAKING CONTROL”
APPLICANT(S)
TATA MOTORS LIMITED
Bombay House, 24 Homi Mody Street,
Hutatma Chowk, Mumbai 400 001, Maharashtra, India; an Indian company.
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed.

FIELD OF THE INVENTION
[0001] The present invention relates to braking of a vehicle, and more specifically related to controlling braking of a vehicle using a non-return valve.
BACKGROUND OF THE INVENTION
[0002] Brakes used in a vehicle, such as a truck, a trailer, a bus, or a car, stop the vehicle when a brake pedal is depressed by a driver of the vehicle. The brakes may be released when the driver takes his foot of the pedal, and the vehicle is free to move thereafter. When the vehicle is stopped on a slope by depressing the brake pedal, the removal of the foot from the brake pedal (e.g., to step on an accelerator pedal) causes the vehicle to automatically roll downwards due to gravity. For example, if the vehicle is stopped on an upward slope by depressing the brake pedal, a subsequent removal of the foot from the brake pedal may cause the vehicle to roll backwards. Such a backward rolling may continue until a forward thrust, which can be achieved by depressing of an accelerator pedal, overcomes a backward thrust caused by gravity.
[0003] The rolling may harm the vehicle, a nearby vehicle, and passengers of the vehicles. For example, a vehicle rolling backwards from an upward slope may strike another vehicle standing behind the vehicle. The problem of rolling of the vehicle may be more pronounced for vehicles of large size, such as trucks, trailers, and buses, due to their large weight. Further, the problem of rolling is more pronounced when the slope is high (e.g., on hills).
[0004] Conventional techniques used for preventing rolling of vehicles involves usage of a large number of components, such as a double-check valve, a pressure sensor, ABS modulator valve (in some cases), and the like. The usage of the large number of components increases the complexity and cost of the vehicles. Further, the usage of the large number of components may also increase the response time,

i.e., the time elapsed from the depression of the brake pedal to a complete stoppage of the vehicle.
SUMMARY OF THE INVENTION
[0005] A braking system for a vehicle includes a first braking element, a second braking element, and a non-return (NR) valve connected between the first braking element and the second braking element to allow flow of a valve fluid between the first braking element and the second braking element. The flow of the valve fluid from the first braking element to the second braking element causes braking of the vehicle, and the flow of the valve fluid from the second braking element to the first braking element causes release of the braking. The NR valve can be activated to prevent the flow of the valve fluid from the second braking element to the first braking element. A control unit activates the NR valve in response to an indication that a command to brake the vehicle is issued.
BRIEF DESCRIPTION OF DRAWINGS
[0006] The features, aspects, and advantages of the subject matter will be better
understood with regard to the following description, and accompanying figures.
The use of the same reference number in different figures indicates similar or
identical features and components.
[0007] Fig. 1 illustrates a controllable non-return valve (CNRV), according to an
implementation of the present subject matter.
[0008] Fig. 2 illustrates a CNRV in a state in which a piston is pushed against a
piston seat, according to an implementation of the present subject matter.
[0009] Fig. 3 illustrates a vehicle in which release of braking is controlled using a
braking system, according to an implementation of the present subject matter.
[0010] Fig. 4 illustrates a braking system for controlling release of the braking
using CNRVs, according to an implementation of the present subject matter.

[0011] Fig. 5 illustrates a braking system for controlling braking of front and rear
tyres of a vehicle using CNRVs, according to an implementation of the present
subject matter.
[0012] Fig. 6 illustrates a braking system for a vehicle without ABS functionality
in which braking is controlled using a CNRV, according to an implementation of
the present subject matter.
[0013] Fig. 7 illustrates a method for controlling braking of a vehicle, according to
an implementation of the present subject matter.
DETAILED DESCRIPTION OF INVENTION
[0014] The present subject matter relates to controlling braking of a vehicle based on a non-return valve. Using techniques of the present subject matter, rolling of a vehicle under the influence of gravity can be prevented in a simple and efficient manner.
[0015] In accordance with an implementation of the present subject matter, a non-return (NR) valve is provided in a fluid path between a first braking element and a second braking element of a vehicle. The first braking element and the second braking element may be components involved in enabling braking of the vehicle and releasing of the braking. In an example, the first braking element may be a brake valve that is connected to a brake pedal of the vehicle and that is to supply a relaying fluid to a relay valve upon depression of the brake pedal. Further, the second braking element may be the relay valve, which is to supply a braking fluid to a brake chamber or a brake actuator of the vehicle in response to receiving the relaying fluid from the brake valve, for braking the vehicle. In another example, the first braking element may be the relay valve and the second braking element may be the brake actuator or the brake chamber, which is to activate a brake coupled thereto in response to receiving the braking fluid from the relay valve.
[0016] A flow of a valve fluid, which may be either the relaying fluid or the braking fluid, from the first braking element to the second braking element causes braking

of the vehicle. For instance, as explained above, a flow of the relaying fluid from the brake valve to the relay valve, or flow of the braking fluid from the relay valve to the brake chamber/brake actuator causes braking of the vehicle. A flow of the valve fluid in the reverse direction, i.e., from the second braking element to the first braking element causes release of the braking.
[0017] The NR valve allows the valve fluid to pass from the first braking element to the second braking element at all times. Further, the NR valve allows the flow of the valve fluid in the reverse direction when the NR valve is not activated, and blocks the flow of the NR valve fluid in the reverse direction when the NR valve is activated. Accordingly, when the NR valve is activated, the release of braking is prevented.
[0018] The activation of the NR valve may be performed by a control unit, such as an electronic control unit (ECU), of the vehicle. The control unit may activate the NR valve in response to an indication that a command to brake the vehicle is issued. The command to brake the vehicle may be issued by the driver of the vehicle, for example, by depressing the brake pedal. The control unit may maintain the NR valve in an activated state even after the command to brake the vehicle is removed (such as after removal of driver’s foot from the brake pedal). Accordingly, the release of braking is prevented even after the driver takes his foot off the pedal, for example, to step on the accelerator pedal. Thus, the rolling of the vehicle under the influence of gravity is prevented. The NR valve may be maintained in the activated state, for example, until the expiry of a predetermined period from the removal of the command, or until receipt of a command to accelerate the vehicle.
[0019] Since the activation of the NR valve can be controlled, the NR valve may be referred to as controllable NR valve, or CNR valve. In an implementation, the CNR valve includes a housing through which the valve fluid can flow. A first end of the housing is connected to the first braking element and a second end of the housing is connected to the second braking element. A piston seat is provided

between the first end and the second end, and a piston is provided between the piston seat and the second end. A plunger connected to the piston can move the piston towards and away from the piston seat. In an example, the plunger moves the piston towards from the piston seat, and pushes the piston against the piston seat, when a control signal is supplied to a coil surrounding the plunger. In another example, the plunger moves the piston towards from the piston seat when the control signal supplied to the coil is removed. The control signal may be supplied to the coil by the ECU. The CNR valve may be said to be in the activated state when the piston pushes against the piston seat.
[0020] The CNR valve of the present subject matter enables preventing rolling of the vehicle under the influence of gravity in a simple manner. Further, the usage of the CNR valve eliminates the usage of multiple other components for preventing the rolling, such as pressure sensor, double-check valve, and the like.
[0021] The implementations herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting implementations that are illustrated in the accompanying drawings and detailed in the following description. It should be understood, however, that the following descriptions, while indicating preferred implementations and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the implementations herein without departing from the spirit thereof, and the implementations herein include all such modifications. The examples used herein are intended merely to facilitate an understanding of ways in which the implementations herein can be practiced and to further enable those skilled in the art to practice the implementations herein. Accordingly, the examples should not be construed as limiting the scope of the implementations herein.
[0022] Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the implementations herein. Also, the

various implementations described herein are not necessarily mutually exclusive, as some implementations can be combined with one or more other implementations to form new implementations.
[0023] Referring now to the drawings, and more particularly to Figs. 1 through 7, where similar reference characters denote corresponding features consistently throughout the figures, there are shown preferred implementations. Further, for the sake of simplicity, and without limitation, the same numbers are used throughout the drawings to reference like features and components. The implementations herein will be better understood from the following description with reference to the drawings.
[0024] Fig. 1 illustrates a non-return (NR) valve 100, according to an implementation of the present subject matter. The NR valve 100 may also be referred to NRV 100. The NR valve 100 may be used in a vehicle (not shown in Fig. 1), such as a commercial vehicle (e.g., bus, truck, and trailer) or a passenger vehicle (e.g., car), for controlling braking of the vehicle. The NR valve 100 may be provided in a fluid path between a first element and a second element of the vehicle that are involved in the braking of the vehicle. The first element and the second element may be referred to as the first braking element and the second braking element respectively. In an example, the first braking element and the second braking element may be a brake valve and a relay valve respectively. In another example, the first braking element and the second braking element may be a relay valve and a brake chamber respectively. The various examples of the braking elements and their functions will be explained below with reference to Figs. 3-6.
[0025] The NR valve 100 may include a housing 102. The housing 102 may be hollow and may accommodate other components of the NR valve 100. In an example, the housing 102 may be cylindrical in shape. Through the housing 102, a fluid may flow between the first braking element and the second braking element, i.e., from the first braking element to the second braking element and from the

second braking element to the first braking element. The fluid passing through the housing 102 may be referred to as a valve fluid. The braking elements may be coupled at ends of the housing 102, such as ends of the housing 102 in a lengthwise direction of the housing. For example, the housing 102 may include a first end 104 at which the first braking element may be connected, and a second end 106 at which the second braking element may be connected.
[0026] In the housing 102, a piston 108 may be provided. The piston 108 may be coaxial to the housing 102. The piston 108 may be movable in the housing 102 in the lengthwise direction of the housing 102. Accordingly, the piston 108 can move in a first direction 110 extending from the first end 104 to the second end 106 and in a second direction 112 extending from the second end 106 to the first end 104.
[0027] The NR valve 100 may also include a piston seat 114. The piston seat 114 may be disposed between the first end 104 and the second end 106. In an example, the piston seat 114 may be fixedly attached to an inner wall 118 of the housing 102, and may protrude from the inner wall 118 vertically towards the centre of the housing 102.
[0028] The piston 108 may be provided between the piston seat 114 and the second end 106. Accordingly, when the piston 108 moves in the first direction 110, the piston 108 moves away from the piston seat 114, and when the piston moves in the second direction 112, the piston 108 moves towards the piston seat 114. Further, the piston seat 114 and the piston 108 may be designed such that the piston 108 cannot move beyond the piston seat 114 in the second direction 112. That is, the movement of the piston 108 in the second direction 112 is restricted by the piston seat 114.
[0029] In an example, the piston 108 has a hollow body 120 through which the valve fluid can flow. The piston 108 includes an axial wall 122 at an axial end of the piston 108. The axial wall 122 may face the piston seat 114 and may be the part

of the piston 108 that comes in contact with the piston seat 114 when the piston 108 is pushed against the piston seat 114. The axial wall 122 may be solid, i.e., devoid of an opening. Accordingly, the valve fluid moving from the first end 104 in the first direction 110 and striking the axial wall 122 cannot enter the hollow body 120 through the axial wall 122. Similarly, the valve fluid moving from the second end 106 in the second direction 112 and striking the axial wall 122 cannot exit the hollow body 120 through the axial wall 122.
[0030] The piston 108 also includes a radial wall 124. The radial wall 124 may be disposed at a radial end of the piston 108. The radial wall 124 is attached to the axial wall 122 and is disposed between the axial wall 122 and the second end 106. The radial wall 124 may include a radial wall opening 126 through which the valve fluid can enter and exit the hollow body 120. For example, the valve fluid flowing from the first end 104 in the first direction 110 can enter the hollow body 120 through the radial wall opening 126. Similarly, the valve fluid flowing from the second end 106 in the second direction 112 can exit the hollow body 120 through the radial wall opening 126, and move towards the first end 104.
[0031] The NR valve 100 further includes a plunger 128 that is coupled to the piston 108 and that can move the piston 108 in the first direction 110 and the second direction 112. The plunger 128 may include a first plunger portion 130 that is disposed in the housing 102. The first plunger portion 130 may be disposed between the piston 108 and the second end 106. A remainder of the plunger 128, which is outside the housing 102, may be referred to as a second plunger portion 132. The first plunger portion 130 may be coupled to the piston 108 through a spring wall 134 and a spring 136. The spring 136 may also be referred to as a piston spring 136. In an example, the radial wall 124 may include a first radial wall portion 138 and a second radial wall portion 140. The second radial wall portion 140 may be disposed closer to the second end 106 than the first radial wall portion 138. The piston spring 136 may be coupled to the second radial wall portion 140. In an example, the second radial wall portion 140 may have a diameter such that it can accommodate the

spring 136. Further, the piston spring 136 may abut against the second radial wall portion 140.
[0032] The spring 136 may be hollow at its centre, with the hollow portion of the spring 136 being aligned with the hollow body 120 of the piston 108. Further, the first plunger portion 130 and the spring wall 134 may have openings that are aligned with the hollow body 120 and the hollow portion of the spring 136. Thus, the valve fluid entering from the second end 106 can pass through the opening of the first plunger portion 130, the opening of the spring wall 134, the spring 136, and the hollow body 120, and exit through the radial wall opening 126. The valve fluid may subsequently exit the housing 102 through the first end 104. Similarly, the valve fluid entering through the first end 104 enters the radial wall opening 126 and flow through the hollow body 120, the spring 136, the opening of the spring wall 134, and the opening of the first plunger portion 130, and exit through the second end 106.
[0033] In an implementation, the first plunger portion 130 includes a slider 142 that is parallel to an axis 143 of the housing 102. The slider 142 may be in contact with the inner wall 118 and may slide along the inner wall 118 during movement of the plunger 128. In an example, a lining 144 of a material having low friction may be provided on the inner wall 118, and the slider 142 may slide along the lining 144. The provision of the lining 144 reduces friction during movement of the plunger 128.
[0034] The plunger 128 can be actuated to push the piston 108 against the piston seat 114. To facilitate movement of the plunger 128, in an implementation, the plunger 128 may be connected to a spring 146, also referred to as a plunger spring 146. The plunger spring 146 may be connected to an end of the second plunger portion 132. Further, at least a portion of the second plunger portion 132 and at least a portion of the plunger spring 146 may be surrounded by a coil 148. The plunger spring 146 biases the plunger 128 away from the coil 148.

[0035] The coil 148, the plunger spring 146, and the plunger 128 may work as part of a solenoid valve 150. For instance, the plunger 128 may be made of a magnetic material, such as a ferromagnetic material. When an electric current is passed through the coil 148, a magnetic field is generated, which attracts the plunger 128 towards the coil 148. Accordingly, the plunger 128 overcomes the biasing force exerted by the plunger spring 146, compresses the plunger spring 146, and moves towards the coil 148. For example, the plunger 128 moves in a left-hand side direction in the view as illustrated in Fig. 1, and a length of the second plunger portion 132 that is surrounded by the coil 148 increases. Further, the first plunger portion 130 moves in the second direction 112, thereby moving the piston 108 also in the second direction 112, i.e., towards the piston seat 114. Thus, the piston 108 is pushed against the piston seat 114.
[0036] When supply of the electric current to the coil 148 is stopped, the second plunger portion 132 moves in the right-hand side direction, as the attractive force ceases to exist and as the plunger spring 146 expands. This moves the piston 108 in the first direction 110, i.e., away from the piston seat 114.
[0037] Fig. 2 illustrates the NR valve 100 in a state in which the piston 108 is pushed against the piston seat 114, according to an implementation of the present subject matter. When electric current is supplied to the coil 148, the plunger 128 is attracted towards the coil 148, causing the plunger 128 to move in a left-hand side direction 202. The movement of the plunger 128 is imparted to the piston 108 through the spring wall 134 and the piston spring 136, causing the piston 108 to be pushed against the piston seat 114. The state of the NR valve 100 in which the piston 108 is pushed against the piston seat 114 may be referred to as an activated state of the NR valve 100. Correspondingly, the state of the NR valve 100 in which the piston 108 is away from the piston seat 114 may be referred to as a deactivated state of the NR valve 100. Since the NR valve 100 can be controlled to be in activated and deactivated states (by supplying electric current and removing supply

of the electric current to the coil 148), the NR valve 100 may also be referred to as controllable NR valve 100, CNR valve 100, or CNRV 100. Further, since the NR valve 100 is controlled using electric current supplied to the coil 148, the electric current may be referred to as a control signal.
[0038] When the CNR valve 100 is in the activated state, as illustrated in Fig. 2, a flow of the valve fluid in the second direction 112 is blocked. For instance, one portion of the valve fluid entering from the second end 106 exits the radial wall opening 126 and is blocked by the piston seat 114. Another portion of the valve fluid entering from the second end 106 strikes the axial wall 122. Since the axial wall 122 is solid, the remaining portion of the valve fluid fails to move past axial wall 122. Instead, the valve fluid pushes the axial wall 122 against the piston seat 114.
[0039] Even though the valve fluid flowing in the second direction 112 is blocked, the valve fluid flowing in the first direction 110 is allowed to flow. For instance, the valve fluid entering the housing 102 from the first end 104 moves in the first direction 110 and strikes the axial wall 122 from the left-hand side of the axial wall 122. Such valve fluid pushes the piston 108 in the first direction 110, i.e., away from the piston seat 114. Consequently, the piston 108 gets pushed away slightly from the piston seat 114 and moves towards the first plunger portion 130, causing compression of the piston spring 136. Accordingly, a clearance is established between the piston seat 114 and the piston 108. Through the clearance, the valve fluid entering from the first end 104 passes, and enters the radial wall opening 126. The valve fluid then passes through the hollow body 120, the piston spring 136, the opening of the spring wall 134, and the opening of the first plunger portion 130, and exits through the second end 106.
[0040] As will be appreciated from the above, when the CNR valve 100 is activated, the valve fluid is allowed to pass from the first end 104 to the second end 106, but not from the second end 106 to the first end 104. Such a property of the

CNR valve 100 can be leveraged to keep the brakes of the vehicle applied even when a driver of the vehicle has taken his foot off a brake pedal of the vehicle. For instance, the vehicle may be such that a flow of the valve fluid from the second braking element to the first braking element causes release of braking of the vehicle. Further, such a flow may typically happen when the brake pedal is released. By connecting the second end 106 to the second braking element and the first end 104 to the first braking element, for an activated state of the CNR valve 100, a flow of the valve fluid from the second braking element to the first braking element is prevented, even if the brake pedal is released. Further, the vehicle may be such that a flow of the valve fluid from the first braking element to the second braking element causes braking of the vehicle, and such a flow typically happens when the brake pedal is depressed. Since the valve fluid is allowed to flow from the first end 104 (which is connected to the first braking element) to the second end 106 (which is connected to the second braking element) even during an activated state of the CNRV 100, it is ensured that braking of the vehicle 100 is not hampered by operation of the CNRV 100.
[0041] The first braking element, the second braking element, and the interaction of the CNRV 100 with the braking elements will be explained below with reference to Figs. 3-6.
[0042] Although Figs. 1 and 2 are explained with reference to scenarios in which the NR valve 100 is activated (i.e., the piston 108 is pushed against the piston seat 114) when control signal is received by the coil 148, in an example, the NR valve 100 may be so designed that the NR valve 100 remains deactivated when the control signal is supplied, and when no control signal is supplied to the coil 148, the NR valve 100 gets activated.
[0043] Fig. 3 illustrates a vehicle 300 in which release of the braking is controlled using a braking system 301, according to an implementation of the present subject matter. The vehicle 300 may be a commercial vehicle (CV), such as a truck, a bus,

or a trailer. The braking system 301 includes a CNRV 302. The CNRV 302 may correspond to the CNRV 100. The CNRV 300 may be connected to a first braking element, which may be a brake valve 304, and a second braking element, which may be a relay valve 306.
[0044] The brake valve 304 may be coupled to a brake pedal 308, which can be depressed by a driver of the vehicle 300 using his foot. The brake valve 304 may supply a valve fluid upon depression of the brake pedal 308 to cause braking of the vehicle 300. The valve fluid may be, for example, air. The relay valve 306, upon receiving the valve fluid, allows flow of a braking fluid stored in a braking fluid tank 310 to brake actuators 312-318 to cause the braking. The braking fluid may be, for example, air, and the braking fluid tank 310 may be referred to as air tank 310. As will be understood, the use of the relay valve 306 reduces the time required for braking the vehicle 300 pursuant to depressing of the brake pedal 308.
[0045] Each brake actuator may be connected to slack adjuster corresponding to a rear tyre (not shown in Fig. 3) of the vehicle 300 to cause braking of the corresponding rear tyre. If the vehicle 300 is implementing an antilock braking system (ABS), the vehicle 300 may include modulator valves (MVs) 320 and 322. If the ABS is activated, the MVs may modulate the flow of air to the brake actuators. The flow of air to the brake actuators causes braking of the vehicle 300. The manner in which the braking of the vehicle 300 is achieved due to the flow of air to the brake actuators will be understood by a person skilled in the art, and is not explained herein for the sake of brevity.
[0046] As explained above, the flow of the valve fluid from the brake valve 304 to the relay valve 306 causes braking of the vehicle 300. When the valve fluid flows in the reverse direction, i.e., from the relay valve 306 to the brake valve 304, the braking fluid flows back to the braking fluid tank 310 from the brake actuators 312-318, thereby causing release of the braking. The valve fluid tends to flow in the reverse direction in response to release of the brake pedal 308.

[0047] The CNRV 302 may be utilized to prevent the flow of the valve fluid in the reverse direction. For example, as explained above, the CNRV 100 can be activated to prevent the flow of the valve fluid from the second braking element to the first braking element. Similarly, the CNRV 302 (which corresponds to the CNRV 100) can be activated to prevent the flow of the valve fluid from the relay valve 306 (which corresponds to the second braking element) to the brake valve 304 (which corresponds to the first braking element). Accordingly, when the CNRV 302 is activated, the release of the braking is prevented even if the brake pedal 308 is released.
[0048] The activation of the CNRV 302 may be performed by a control unit 324 of the vehicle 300. The control unit 324 may be implemented, for example, as a microprocessor, a microcomputer, a microcontroller, a digital signal processor, a logic circuitry, and/or any device that manipulates signals based on operational instructions. Among other capabilities, the control unit 324 may fetch and execute computer-readable instructions included in a memory (not shown in Fig. 3). The functions of the control unit 324 may be provided through the use of dedicated hardware as well as hardware capable of executing machine-readable instructions. In an example, the control unit 324 may be an electronic control unit (ECU) in the vehicle 300. The control unit 324 may activate the CNRV 302, for example, by sending a control signal to a coil (not shown in Fig. 3) of the CNRV 302 or by stopping transmission of the control signal to the coil, as explained earlier. The sending of the control signal to the coil (or, in another implementation, the stoppage of transmission of the control signal to the coil) may cause actuation of a plunger of the CNRV 302, thereby activating the CNRV 302.
[0049] The control unit 324 may activate the CNRV 302 in response to an indication that a command to brake the vehicle 302 is issued. The command may be issued by the driver of the vehicle 302, for example, by depressing the brake pedal 308. In an example, the control unit 324 may keep the CNRV 302 activated

for a predetermined period of time, such as three seconds, after removal of the command, and may deactivate the CNRV 302 thereafter, to allow flow of the valve fluid from the relay valve 306 to the brake valve 304. Thus, the brakes of the vehicle 300 are not released until expiry of the predetermined period of time after release of the brake pedal 308 by the driver. In another example, the control unit 324 may deactivate the CNRV 302 in response to an indication that a command to accelerate the vehicle 300 is issued. The command to accelerate the vehicle 300 may be issued by the driver, for example, by depressing an accelerator pedal (not shown in Fig. 3) of the vehicle 300. Thus, the vehicle 300 remains braked until the driver depresses the accelerator pedal.
[0050] In accordance with both the above examples, the vehicle 300 remains braked even after release of the brake pedal 308 by the driver for a brief period of time. Thus, the rolling downwards of the vehicle 300 in response to release of the brake pedal 308, which may otherwise happen when the vehicle 300 is stopped on an upward or downward slope, is prevented.
[0051] In an implementation, the functionality to control the release of braking, as explained above, may be enabled and disabled, for example, by a driver of the vehicle 300. When the functionality is disabled, the brakes are released as soon as the driver takes his foot off the brake pedal 308. To facilitate the enabling and disabling, a braking assist (BA) switch 326 may be provided in the vehicle 300 and may be connected to the control unit 324. In response to turning on of the BA switch 326, for example, by the driver, the functionality to control the release of braking may be enabled. For instance, the control unit 324 may activate and deactivate the CNRV 302 as explained above. In response to turning off of the BA switch 326, the control unit 324 disables the functionality to control the release of braking. The control unit 324 may disable the functionality by not activating the CNRV 302 when the brake pedal 308 is depressed. The functionality may be disabled, for example, when the vehicle 300 is travelling on plains.

[0052] Although, in Fig. 3, the CNRV is shown to be disposed in the fluid path between the brake valve and the relay valve, in an example, the CNRV may be disposed in another position in a vehicle, while still preventing the rolling of the vehicle in response to release of the brake pedal, as will be explained below.
[0053] Fig. 4 illustrates a braking system 400 for controlling release of the braking using CNRVs, according to an implementation of the present subject matter. Here, like components from Fig. 3 are illustrated with the same reference numbers as Fig. 3. The braking system 400 may be part of a vehicle (not shown in Fig. 4).
[0054] The braking system 400 includes a first CNRV 402 and a second CNRV 404. Each of the first CNRV 402 and the second CNRV 404 corresponds to the CNRV 100 and the CNRV 302. The first CNRV 402 may be disposed in the fluid path between the first MV 320 and the brake actuators 312 and 314. Accordingly, a braking fluid that is to flow from the first MV 320 to the first and second brake actuators 312 and 314 and a braking fluid that is to flow in the reverse direction flow through the first CNRV 402. The second CNRV 404 may be disposed in the fluid path between the second MV 322 and the brake actuators 316 and 318. Accordingly, a braking fluid that is to flow from the second MV 322 to the third and fourth brake actuators 312 and 314 and a braking fluid that is to flow in the reverse direction flow through the second CNRV 402.
[0055] In accordance with the implementation of Fig.4, the valve fluid, i.e., the fluid that passes through the CNRVs, is the braking fluid. Further, the first MV 320 and the second MV 322 correspond to the first braking element and the brake actuators 312-218 correspond to the second braking element.
[0056] The control unit 324 may activate the first CNRV 402 and the second CNRV 404 in response to depression of the brake pedal 308, and deactivate them after expiry of the predetermined period of time from the release of the brake pedal 308 or after depressing of the accelerator pedal. Therefore, release of the brakes,

which may happen due to flow of the braking fluid from the brake actuators to the MVs, is stalled for a brief period of time after release of the brake pedal 308.
[0057] In the above explanation, the CNRVs are explained as being used for controlling braking of the rear tyres of a vehicle. However, the CNRVs can be used for controlling braking of the front tyres as well, as explained below.
[0058] Fig. 5 illustrates a braking system 500 for controlling braking of front and rear tyres of a vehicle using CNRVs, according to an implementation of the present subject matter. In addition to the brake actuators 312-318, the braking system 500 may also include brake chambers 502-508. Each brake chamber may correspond to a front tyre (not shown in Fig. 5) of the vehicle, and may cause braking of the corresponding front tyre. The braking fluid for braking of the front tyres may be supplied by a front braking fluid tank 510, and the braking fluid for braking of the rear tyres may be supplied by a rear braking fluid tank 512. The braking system 500 further includes a first relay valve 514 corresponding to the rear tyres and a second relay valve 516 corresponding to the front tyres. The first relay valve 514 and the second relay valve 516 have a structure and functions similar to those of the relay valve 306. Further, a first MV 518 and a second MV 520 correspond to the rear tyres and a third MV 522 and a fourth MV 524 correspond to the front tyres.
[0059] A first CNRV 526 is disposed in a fluid path between the brake valve 304 and the first relay valve 514, and a second CNRV 528 is disposed in a fluid path between the brake valve 304 and the second relay valve 516. The first CNRV 526 and the second CNRV 528 correspond to the CNRV 100, and are controlled by the control unit 324. Accordingly, the first CNRV 526 and the second CNRV 528, when activated by the control unit 324, prevent release of the rear brakes and the front brakes of the vehicle and prevent the vehicle from rolling downwards.
[0060] The provision of CNRVs corresponding to both front and rear tyres ensures that the vehicle does not roll downwards under the influence of gravity upon release

of the brake pedal 304, even when the vehicle is on a terrain with a high slope and even when the vehicle is heavily loaded.
[0061] Although control of braking is explained with reference to vehicles having ABS functionality, the techniques of the present subject matter can be implemented in vehicles without ABS functionality as well, as explained below.
[0062] Fig. 6 illustrates a braking system 600 for a vehicle without ABS functionality in which braking is controlled using a CNRV, according to an implementation of the present subject matter. As illustrated, the braking system 600 is devoid of MVs, as the vehicle does not have ABS functionality. The CNRV 302 may be disposed in the fluid path between the brake valve 304 and the relay valve 306, and can be activated to prevent the flow of the valve fluid from the relay valve 306 to the brake valve 306, as explained above.
[0063] Fig. 7 illustrates a method 700 for controlling braking of a vehicle, according to an implementation of the present subject matter. It may be understood that steps of the method 700 may be performed by a programmed computing unit, such as the control unit 324, of the vehicle. The steps of the method 700 may be executed based on instructions stored in a non-transitory computer readable medium, as will be readily understood. The non-transitory computer readable medium may include, for example, digital memories.
[0064] The order in which the method 700 is described is not intended to be construed as a limitation, and any number of the described method blocks can be combined in any order to implement the method 700, or an alternative method. Additionally, individual blocks may be deleted from the method 700 without departing from the scope of the subject matter described herein. Furthermore, the method 700 can be implemented in any suitable hardware, non-transitory machine-readable instructions, or combination thereof. A person skilled in the art will readily recognize that steps of the method 700 can be performed by programmed

computing devices. Herein, some examples are also intended to cover program storage devices, for example, digital data storage media, which are machine or computer-readable and encode machine-executable or computer-executable programs of instructions, wherein said instructions perform some or all of the steps of the described method. The program storage devices may be, for example, digital memories.
[0065] At block 702, an indication is received that a command to brake the vehicle is provided. The command may be provided by a driver of the vehicle by depressing a brake pedal of the vehicle.
[0066] In response to the indication, at block 704, a non-return (NR) valve of the vehicle is activated. The NR valve may be, for example, the CNRV 100. The NR valve is connected between a first braking element and a second braking element of the vehicle to allow flow of a valve fluid between the first braking element and the second braking element. The flow of the valve fluid from the first braking element to the second braking element causes braking of the vehicle. The flow of the valve fluid from the second braking element to the first braking element causes release of the braking, as explained earlier. The activation of the NR valve causes the flow of the valve fluid from the first braking element to the second braking element and blocks the flow of the valve fluid from the second braking element to the first braking element.
[0067] At block 706, the NR valve is deactivated. The deactivation may be performed in response to elapse of a predetermined period of time after removal of the command to brake the vehicle. Alternatively, the deactivation may be performed in response to receipt of a command to accelerate the vehicle.
[0068] Although the present subject matter is explained with reference to vehicles having relay valves, the present subject matter can be implemented in vehicles without relay valves. For example, in a vehicle in which a braking fluid flows from

a brake valve to a brake actuator or a brake chamber, without an intervening relay valve, the CNRV may be provided in the fluid path between the brake valve and the brake actuator/brake chamber. In accordance with the example, the first braking element may be the brake valve and the second braking element may be the brake actuator/brake chamber. Further, in a vehicle in which a braking fluid flows from a brake valve to an MV, without an intervening relay valve, the CNRV may be provided in the fluid path between the brake valve and the MV. In accordance with the example, the first braking element may be the brake valve and the second braking element may be the MV.
[0069] Although, in the above explanation, the braking fluid is explained as air, the present subject matter can be implemented in vehicles using other types of braking fluid, such as hydraulic braking fluid. Further, although the present subject matter is explained with reference to CVs, the techniques of the present subject matter can be implemented in other types of vehicles, such as passenger vehicles (PVs).
[0070] The CNR valve of the present subject matter enables preventing rolling of the vehicle under the influence of gravity in a simple manner. Further, the usage of the CNR valve eliminates the usage of multiple other components for preventing the rolling, such as pressure sensor, double-check valve, and the like. The techniques of the present subject matter can be utilized in different types of vehicles, such as CVs and PVs. Further, the techniques of the present subject matter can be utilized in vehicles with multiple axles, such as 2-6 axles.
[0071] The foregoing description of the specific implementations will so fully reveal the general nature of the implementations herein that others can, by applying current knowledge, readily modify and/or adapt for various applications without departing from the generic concept, and, therefore, such modifications and adaptations should and are intended to be comprehended within the meaning and range of equivalents of the disclosed implementations. It is to be understood that the phraseology or terminology employed herein is for the purpose of description

and not of limitation. Therefore, while the implementations herein have been described in terms of preferred implementations, those skilled in the art will recognize that the implementations herein can be practiced with modification within the spirit and scope of the implementations as described herein.

We Claim:
1. A non-return (NR) valve for a vehicle, the NR valve comprising:
a housing through which a valve fluid is to flow between a first braking element of the vehicle and a second braking element of the vehicle, the housing comprising:
a first end to be coupled to the first braking element; and
a second end to be coupled to the second braking element, wherein a flow of the valve fluid from the first braking element to the second braking element causes braking of the vehicle, and wherein a flow of the valve fluid from the second braking element to the first braking element causes release of the braking;
a piston seat fixedly disposed in the housing between the first end and the second end;
a piston disposed between the piston seat and the second end, wherein the piston is movable in the housing towards and away from the piston seat; and
a plunger coupled to the piston to move the piston, wherein the plunger is actuatable by a control unit of the vehicle, and wherein, in response to the actuation, the plunger pushes the piston against the piston seat, to prevent flow of the valve fluid from the second braking element to the first braking element.
2. The NR valve as claimed in claim 1, comprising:
a coil to be coupled to the control unit to receive a control signal, wherein, to actuate the plunger, the control unit is to one of: send a control signal to the coil and stop sending a control signal to the coil.
3. The NR valve as claimed in claim 2, comprising a solenoid valve comprising
the coil and the plunger, wherein the solenoid valve further comprises:
a plunger spring coupled to the plunger, wherein the coil surrounds at least a portion of the plunger spring and the plunger.

4. The NR valve as claimed in claim 1, wherein the piston is coaxial to the
housing and comprises:
a hollow body through which the valve fluid is to flow;
an axial wall at an axial end of the piston, the axial wall to be in contact with the piston seat when the piston is pushed against the piston seat, wherein when the piston is pushed against the piston seat, the valve fluid flowing from the first end pushes the axial wall away from the piston seat and the valve fluid flowing from the second end pushes the axial wall against the piston seat; and
a radial wall disposed between the axial wall and the second end, the radial wall having a radial wall opening through which the valve fluid from the first end is to enter the hollow body and through which the valve fluid from the second end is to exit the hollow body.
5. The NR valve as claimed in claim 4, wherein the plunger comprises a first plunger portion disposed in the housing and between the piston and the second end, wherein the first plunger portion has an opening that is aligned with the hollow body to allow flow of the valve fluid between the hollow body and the second end.
6. The NR valve as claimed in claim 5, comprising a piston spring coupled to and disposed between the piston and the first plunger portion, wherein, when the piston is pushed against the piston seat, a movement of the valve fluid from the first end causes the piston to move towards the first plunger portion and compression of the piston spring.
7. A braking system for a vehicle, the braking system comprising:
a first braking element;
a second braking element;
a non-return (NR) valve connected between the first braking element and the second braking element to allow flow of a valve fluid between the first braking element and the second braking element, wherein the flow of the valve fluid from the first braking element to the second braking element causes braking of the

vehicle, wherein the flow of the valve fluid from the second braking element to the first braking element causes release of the braking, and wherein the NR valve is activatable to prevent the flow of the valve fluid from the second braking element to the first braking element; and
a control unit to activate the NR valve in response to an indication that a command to brake the vehicle is issued.
8. The braking system as claimed in claim 7, wherein the control unit is to
deactivate the NR valve, to allow flow of the valve fluid from the second braking
element to the first braking element, in response to one of:
expiry of a predetermined period of time after removal of the command to brake the vehicle; and
an indication that a command to accelerate the vehicle is issued.
9. The braking system as claimed in claim 7, wherein the NR valve comprises:
a housing through which the valve fluid is to flow between the first braking
element and the second braking element, the housing comprising:
a first end coupled to the first braking element; and
a second end coupled to the second braking element;
a piston seat fixedly disposed in the housing between the first end and the second end;
a piston disposed between the piston seat and the second end, wherein the piston is movable in the housing towards and away from the piston seat; and
a plunger coupled to the piston to move the piston, wherein, in response to activation of the NR valve, the plunger pushes the piston against the piston seat.
10. The braking system as claimed in claim 9, wherein the NR valve comprises:
a piston spring coupled to the plunger; and
a coil surrounding at least a portion of the plunger and the spring, wherein, to activate the NR valve, the control unit is to:
supply an electric current to the coil; or

stop supply of electric current to the coil.
11. A vehicle comprising:
a first braking element;
a second braking element;
a non-return (NR) valve connected between the first braking element and the second braking element to allow flow of a valve fluid between the first braking element and the second braking element, wherein the flow of the valve fluid from the first braking element to the second braking element causes braking of the vehicle, wherein the flow of the valve fluid from the second braking element to the first braking element causes release of the braking, and wherein the NR valve is activatable to prevent the flow of the valve fluid from the second braking element to the first braking element; and
a control unit to activate the NR valve in response to an indication that a command to brake the vehicle is issued.
12. The vehicle as claimed in claim 11, wherein the first braking element is a brake valve connected to a brake pedal of the vehicle and the second braking element is one of: a relay valve connected to a brake of the vehicle and a modulator valve connected to the brake.
13. The vehicle as claimed in claim 11, wherein the first braking element is a modulator valve and the second braking element is one of: a brake actuator connected to a brake of the vehicle and a brake chamber connected to the brake.
14. The vehicle as claimed in claim 11, wherein the first braking element is a brake valve connected to a brake pedal of the vehicle and the second braking element is one of: a brake actuator connected to a brake of the vehicle and a brake chamber connected to the brake.
15. The vehicle as claimed in claim 11, wherein the valve fluid is air.

16. A method for controlling a non-return (NR) valve of a vehicle, the method performed by a control unit of the vehicle and comprising:
receiving an indication that a command to brake the vehicle is provided; and
in response to the indication, activate the NR valve, wherein
the NR valve is connected between a first braking element and a second braking element of the vehicle to allow flow of a valve fluid between the first braking element and the second braking element,
the flow of the valve fluid from the first braking element to the second braking element causes braking of the vehicle,
the flow of the valve fluid from the second braking element to the first braking element causes release of the braking, and
the activation causes the flow of the valve fluid from the first braking element to the second braking element and blocks the flow of the valve fluid from the second braking element to the first braking element; and
deactivating the NR valve in response to:
elapse of a predetermined period of time after removal of the command to brake the vehicle; or
receipt of a command to accelerate the vehicle.