GB2528253A

GB2528253A - Braking system for machine

Info

Publication number: GB2528253A
Application number: GB1412448.1A
Authority: GB
Inventors: Richard Kettle
Original assignee: Caterpillar Shrewsbury Ltd
Current assignee: Caterpillar Shrewsbury Ltd
Priority date: 2014-07-14
Filing date: 2014-07-14
Publication date: 2016-01-20
Anticipated expiration: 2034-07-14
Also published as: GB2528253B; GB201412448D0

Abstract

A braking system includes a brake device 114 coupled with a lever assembly 124 to cause a braking force to be applied to the machine. A first linear actuator 138, preferably a hydraulic piston/cylinder, and a second linear actuator 122, preferably a worm screw 148 driven by electric motor 146, is actuated from a retracted position to an extended position based on a first braking input, preferably a brake pedal, and a second braking input, preferably a parking switch, respectively. A lever assembly 124 is actuated by one of the first linear actuator 138 and the second linear actuator 122. The lever assembly 124 includes a base that includes a slot 152. The second linear actuator 122 is slidably received within the slot 152, by pin 149. A first arm 172 and second arm 174 extends from the base is coupled to the first linear actuator 138 and the brake device 144, respectively. The first linear actuator 138 causes the lever assembly 124 to rotate independently from the second linear actuator 122 when the second linear actuator 122 is in the retracted position.

Description

BRAKING SYSTEM FOR MACHINE

Technical Field

[0001] The present disclosure relates to a braking system for a machine.

Background

[0002] A typical braking system for a machine may include a hydraulic brake system and a parking brake system for separately actuating one or more brake devices of the machine. The hydraulic brake system may include a hydraulic cylinder to actuate the brake devices of the machine. The hydraulic brake system may be associated with service braking and/or emergency braking of the machine. The parking brake system may include a threaded arrangement of a rod arid a cylinder which is actuated electrically.

[0003] The combination of the hydraulic brake system and the parking brake system to separately actuate the brake device may be complex and involve a multitude of components. Due to the threaded arrangement of the parking brake system, the rod and the cylinder is in a locked configuration when the parking brake system is inactive. Hence, during an actuation of the hydraulic brake system, the threaded arrangement of the parking brake system may resist free movement of the hydraulic brake system.

Summary of the Disclosure

10004] In one aspect of the present disclosure, a braking system for a machine is disclosed, The braking system includes a brake device configured to cause a braking force to be applied to the machine, A first linear actuator is configured to be actuated from a retracted position to an extended position based on a first braking input. A second linear actuator is configured to be actuated from a retracted position to an extended position based on a second braking input. A lever assembly is operatively coupled with the brake device. The lever assembly is configured for actuation by at least one of the first linear actuator and the second linear actuator so as to actuate the brake device. The lever assembly includes a base rotatable about an axis, The base defines a slot therein, The second linear actuator is slidably received within the slot. A first arm extending from the base is coupled to the first linear actuator and a second arm extending from the base is operatively coupled to the brake device. An actuation of the first linear actuator causes the lever assembly to rotate and actuate the brake device independently from the second linear actuator when the second linear actuator is in the retracted position. Thus, the slot of the base allows relative movement between the base and the second linear actuator.

[0005] Other features and aspects of this disclosure will be apparent from the following description and the accompanying drawings.

Brief Description of the Drawimzs

[0006] FIG. I is a block diagram illustrating a braking system for a machine, according to an exemplary embodiment of the present disclosure; [0007] FIG. 2 illustrates a side view a lever assembly of the braking system, according to an exemplary embodiment of the present disclosure; [0008] FIG. 3 is a perspective view of the lever assembly, according to an

exemplary embodiment of the present disclosure;

[0009] FIG. 4 is an arrangement of the lever assembly of FIG. 2 in an operational configuration; [0010] FIG. 5 is an arrangement of the lever assembly of FIG. 2 in another operational configuration; and [0011] FIG. 6 is an arrangement of the lever assembly of FIG. 2 in yet another operational configuration.

Detailed Description

[0012] Reference will now be made in detail to exemplary embodiments, which are illustrated with reference to the accompanying drawings. Wherever possible, corresponding or similar reference numbers ll be used throughout the drawings to refer to the same or corresponding parts.

[0013] FIG, shows a block diagram illustrating a braking system 100 for a machine, according to an exemplary embodiment of the present disclosure. The machine may be an on-highway or an off-highway vehicle. For example, the machine may be a loader, a grader, an excavator, and the like. The machine may be any other type of machine associated with various industries such as construction, mining, agriculture, and transportation [0014] Further, in FIG. 1, dotted lines schematically represent electrical communications between various components of the braking system 100.

Mechanical linkages or connections between various components are schematically shown by solid lines, Moreover, hydraulic connections or flows between components are schematically shown as dash-dot lines.

[0015] The braking system 100 may include a service brake system 102 for applying a braking force to the machine so as to control, decelerate and/or stop the motion of the machine, The service brake system 102 may be actuated by a brake pedal 104, The brake pedal 104 may be disposed within an operator cab of the machine. The brake pedal 104 may be operated by an operator of the machine by foot, Although the service brake system 102 is actuated based on a braking input from the operator via the brake pedal 104, it may be contemplated that the braking input may be communicated based on an actuation of a lever or a switch, The brake pedal 104 may include a foot rest at one end thereof and another end may be coupled to a linkage 106, The brake pedal 104 may be moveable between an inactive position and a maximum depressed position based on the braking input from the operator. The linkage 106 may be further coupled to a brake lever 108. The linkage 106 may include one or more members coupled between the brake pedal 104 and the brake lever 08 to actuate the brake lever 108 upon actuation of the brake pedal 04 from the inactive position by the operator.

[0016] The brake lever 108 may be operatively associated with a brake hydraulic system 113. In an exemplary embodiment, the brake hydraulic system 113 may include a valve (not shown) that may be configured to receive an input from the brake lever 108. The valve may be actuated between a closed position and an open position upon actuation by the brake lever 108. The valve may be normally biased to the closed position. Further, the valve may be actuated, for example, mechanically, hydraulically, pneumatically or electrically. The valve may be further fluidly coupled to a brake device 114. The brake device 114 may be operatively coupled to a ground engaging member 116 of the machine. The valve may be configured within the brake hydraulic system 113 to receive a pressurized fluid and to selectively allow or restrict flow of the pressurized fluid to the brake device 114. The valve may allow the pressurized fluid to the brake device 114 upon actuation of the valve to the open position based on a movement of the brake pedal 104 by the operator.

[0017] The brake device 114 is configured to cause a braking force to be applied to the machine. Further the brake device 114 may be configured to be actuated between a disengaged position and an engaged position. In an exemplary embodiment, the ground engaging member 116 may be one of a plurality of wheels, The machine may include at least a pair of front wheels and at least a pair of rear wheels, Each of the pair of front and rear wheels may be coupled with the brake device 114. In another exemplary embodiment, the ground engaging member 116 may include tracks.

[0018] In an exemplary embodiment, the brake device 114 may include a plurality of rotatable discs and a plurality of stationary discs, The rotatable discs may be splined to a wheel hub for rotation therewith and the stationary discs may be connected to a stationary wheel housing. The stationary wheel housing may define a plurality of passages including a fluid supply passage to communicate with the brake hydraulic system 113, A brake piston may be disposed within the stationary wheel housing to move between a released position and a braking position, The released position of the brake piston may correspond to the disengaged position of the brake device 114 and the braking position of the brake piston may correspond to the engaged position of the brake device 114, In the braking position, the brake piston may engage rotatable discs with the stationary discs of the brake device 114, thereby applying a braking force. It may also be contemplated that that the rotatable discs and the stationary discs may also be partially engaged to apply a braking force corresponding to an intermediate position of the brake piston between the released position and the braking position, When the engine of the machine is operational, the valve, based on actuation of the brake lever 108 may allow the pressurized fluid to the fluid supply passage of the stationary wheel housing. Subsequently, the brake piston may move to the braking position to engage the rotatable discs with the stationary discs. Thus, the ground engaging member 6 associated with the brake device 114 may be restricted from rotation to decelerate or stop the machine.

[0019] The braking system 100 further includes an emergency brake system 130, according to an exemplary embodiment of the present disclosure. The emergency brake system 130 may include an accumulator 132. The accumulator 132 may be any type of accumulator such as those known in the art, The accumulator 132 may be fluidly coupled to a machine hydraulic system 118. The machine hydraulic system 118 may supply the accumulator 132 with a pressurized fluid, The machine hydraulic system 118 may any known hydraulic system of the machine, such as a steering system or an implement system, [0020] The accumulator 132 may be frirther fluidly coupled to a first linear actuator 138, The first linear actuator 138 is configured to be actuated from a retracted position to an extended position based on a first braking input. The first braking input may correspond to movement of the brake pedal 104 between the inactive position and the maximum depressed position thereof by the operator during an emergency braking situation of the machine, The first linear actuator 138 may be further operatively coupled to a lever assembly 124. The lever assembly 124 may be operatively coupled to the brake device 114 associated with each of the pair of front wheels or rear wheels, At the maximum depressed position of the brake pedal 104, the pressurized fluid stored in the accumulator 132 may be supplied to the first linear actuator 138, The first linear actuator 138 may move to the extended position from the retracted position to actuate the lever assembly 124, and thereby apply a braking force on the brake device 114. In an exemplary embodiment, the accumulator H2 may be fluidly coupled to the first linear actuator 138 via a valve (not shown) to selectively allow the stored fluid from the accumulator 132 to the first linear actuator 138, The valve may be actuated upon movement of the brake pedal 1 04 to the maximum depressed position.

[0021] It may be contemplated that the first linear actuator 138 may also be associated with the service brake system 102. For example, the brake hydraulic system 113 may actuate the first linear actuator 138 based on a depression of the brake pedal 104.

[0022] The braking system 100 of the machine may further include a parking brake system 120. The parking brake system 120 may include a second linear actuator 122 that may be operatively coupled to the lever assembly 124. The second linear actuator 122 is configured to be actuated from a retracted position to an extended position based on a second braking input. The second linear actuator 122 may be actuated by the operator electrically. The second braking input may correspond to actuation of the second linear actuator 122 through an electric switch t26. The electric switch t26 may selectively actuate the second linear actuator 122 to move to the extended position. The electric switch 126 may be disposed within the operator cab of the machine. When there is a requirement of a braking force to be applied while the machine is stationary, the operator may turn the electric switch 126 ON so that the second linear actuator 122 may move to the extended position and apply a braking force on the brake device 114.

[0023] FIG. 2 is a side view of the lever assembly 124 in association with the first linear actuator 138 and the second linear actuator 122, according to an exemplary embodiment of the present disclosure, The second linear actuator 122 may include a hollow cylindrical body 140 comprising a first end 142 and a second end 144. An electric motor 146 may be mounted adjacent to the first end 142 of the hollow cylindrical body 140. The electric motor 146 may be drivably coupled to a worm screw 148 that may be slidably received through the second end 144 of the hollow cylindrical body 140. The worm screw 148 may slide within the hollow cylindrical body 140 upon actuation of the electric switch 126 to actuate the second linear actuator 122 between the retracted position and the extended position, A free end of the worm screw 148 may be provided with a pin 149 to be slidably coupled to a slot 152 of the lever assembly 124. The lever assembly 124 may be coupled to the brake device 114 associated with the ground engaging member 116. In an example, the lever assembly 124 disposed at the free end of the worm screw 148 may be operatively coupled to the brake device 114 associated with one of the pair of front wheels or one of the pair of rear wheels disposed at a right side of the machine. The first end 142 of the hollow cylindrical body 140 may be slidably coupled to a slot 152 of the lever assembly 124 via a coupling member 151. In an example, the lever assembly 124 disposed at the first end 142 of the hollow cylindrical body 140 may be operatively coupled to the brake device 114 associated with one of the pair of front wheels or one of the pair of rear wheels disposed at a left side of the machine..

Alternatively, the lever assembly 124 may be coupled to multiple brake devices 114 associated with the pair of front wheels or the pair of rear wheels.

[0024] The coupling member 151 may be connected to the first end 142 of the hollow cylindrical body 140. Further, the pin 149 may slidably couple an end of the coupling member 151 to the slot 152 of the lever assembly 124. The coupling member 151 may be connected to the hollow cylindrical body 140 to optimize a length of the second linear actuator 122 between the two lever assemblies 124.

The coupling member may be a solid or a hollow member. The second linear actuator 122 may be moved to the retracted position by moving the electric switch 126 to an OFF position. In an exemplars' embodiment, moving the electric switch 126 to the OFF position may include driving the electric motor 146 in a reverse direction to the direction when moving the second linear actuator 122 to the extended position.

[0025] The electric motor 146 may be in electrical communication with an electric system of the machine, The electric system of the machine may include electric power sources such as, for example, a battery or a generator coupled to the engine for supplying electric power to the electric motor 146 to actuate the worm screw 148. Further, the electric motor N6 may be electrically coupled to the electric switch 126 to selectively actuate the electric motor 146 based on the second braking input from the operator.

[0026] The first linear actuator 138 may be a hydraulic cylinder such as a single acting cylinder or a double acting cylinder. In an exemplary embodiment, the first linear actuator 138 may include a cylinder 154 and a piston (not shown) slidably disposed within the cylinder 154. The cylinder 154 may comprise a head end 158 and a rod end 60. The head end 158 of the cylinder 154 may be fluidly coupled to the accumulator 132 of the emergency brake system 130 through a first port 162 and the rod end 160 of the cylinder 154 may be fluidly coupled to the machine hydraulic system 118 of the emergency brake system 130 through a second port 164. The piston may be coupled to a piston rod 155 that may be movable within the cylinder 154. Upon receipt of the pressurized fluid from the accumulator 132, the piston rod 155 may slide within the cylinder 154 to cause actuation of the first linear actuator 138 between the retracted position and the extended position. A free end of the piston rod 155 may be coupled to the lever assembly 124 via a pin 157. The lever assembly 124 coupled to the free end of the piston rod 155 may be operatively coupled to the brake device 114 associated with the right side of the machine. During actuation of the emergency brake system 130, the fluid stored under the predetermined pressure in the accumulator 132 may flow into the head end 158 of the cylinder 154 and thereby actuate the first linear actuator 138 to move towards the extended position. While receiving the pressurized fluid in the head end 158 of the cylinder 154, the fluid present in the rod end 160 of the cylinder 54 may flow to the machine hydraulic system 118. In an exemplary embodiment, an elastic member such as a coil spring may be disposed in the first linear actuator 138 to move the piston rod 155 to a retracted position upon release of the brake pedal 104 from the maximum depressed position.

[0027] In an exemplary embodiment, the first linear actuator 138 may further include a telescopic arrangement 166. The telescopic arrangement 166 may include a first guiding member 168 that may be connected to the head end 158 of the cylinder 154. The first guiding member 168 may be slidably disposed in a second guiding member 170. The second guiding member 170 may be coupled to the lever assembly 124 via a pin 157. The lever assembly 124 coupled to the second guiding member 170 may be operatively coupled to the brake device 114 associated with the left side of the machine. The first guiding member 68 and the second guiding member 170 may be configured to extend and retract relative to each other.

[0028] The lever assemblies 124 may include a first arm 172 and a second arm 174. The first arm 172 is operatively coupled to the first linear actuator 138 via the pin 157 and the second arm 174 is operatively coupled a link member 178 via a pin 179. The link member 178 maybe further coupled to a lever 180 connected to the brake device 114. Further, the lever assemblies 124 may be rotatably disposed on a frame 150 of the machine via a pivot pin 176. The pivot pin 176 may be integral with the frame 150 or may be separately mounted on the frame 150. The lever assembly 124 may be rotatable about the pivot pin 176 between a first position and a second position. The first position of the lever assembly 124 may correspond to the disengaged position of the brake device 114 and the second position of the lever assembly 124 may correspond to the engaged position of the brake device 114.

[0029] FIG, 3 shows a perspective view of the lever assembly 124, according to an exemplary embodiment of the present disclosure. The lever assembly 124 includes a base 182. A hole 184 may be provided in the base 182 along an axis X'. The hole 184 maybe adapted to rotatably receive the pivot pin 176 (shown in FIG. 2). The base 182 is rotatable about the axis X'. The first ann 172 may extend from the base 182 and provided with a first hole 186. The first hole 186 may be adapted to rotatably receive the pin 157 (shown in FIG. 2) of the first linear actuator 138. The second arm 174 may extend from the base 82 and spaced apart from the first arm 172. Further, the first arm 172 and the second arm 174 may be angularly offset with respect to each other. The second arm 174 may be provided with a second hole 188. The second hole 188 may be adapted to rotatably receive the pin 179 (shown in FIG. 2) to pivotally couple the link member 178 to the second arm 174. The slot 152 is defined in the base 182 and may extend between a first end 190 and a second end 192. As shown in FIG. 2, when the first linear actuator 138 and the second linear actuator 122 are in the retracted position, the pin 149 of the second linear actuator 122 may be positioned at the first end 190 of the slot 152. The lever assembly 124, as described above, is exemplary in nature, and the dimensions and/or shape may vary as per design requirements of the braking system 100.

Industrial Applicability

[0030] A braking system for a machine includes a hydraulic brake system and a parking brake system for separately actuating one or more brake devices of the machine. The hydraulic brake system and the parking brake system may include a pair of lever assemblies to actuate respective brake devices associated with the ground engaging members at right and left sides of the machine. The lever assembly includes a slot to operatively couple to a pin disposed at a free end of the worm screw and a coupling member associated with the parking brake system. Further, the hydraulic braking system is operatively coupled to first arm of the respective lever assemblies. When the hydraulic braking system is actuated, the pins connected to the worm screw and the coupling member may slide through the respective slots without providing any resistance to the actuation of the hydraulic bralcing system. Thus, the lever assemblies of the present disclosure may allow the hydraulic braking system to independently actuate the respective brake devices without any resistance from the parking brake system.

[0031] The present disclosure relates to the braking system 100 including the lever assembly 124. FIG. 4 shows an operational configuration of the lever assembly 124. The operational configuration of the lever assembly 124, as illustrated in FIG. 4, may correspond to an actuation of the emergency brake system 130 while the parking brake system 120 is inactive, in an emergency braking situation of the machine, the operator may depress the brake pedal 104 to the maximum depressed position. At the maximum depressed position of the brake pedal 104, the linkage 106 may move the brake lever 108 to actuate the emergency brake system 130. Upon actuation of the emergency brake system 130, the pressurized fluid stored in the accumulator 132 may flow to the head end 158 of the cylinder 154 of the first linear actuator 138. While receiving the pressurized fluid from the accumulator i32, the first linear actuator 138 may move to the extended position. In the extended position, the first linear actuator 138 coupled between the first arms 172 of the lever assemblies 124 may actuate the lever assemblies 124 to move to the second position. In the second position of the lever assembly 124, the second arm 174 coupled to the link member t78 --1 1--may actuate the brake device 114 to move the brake device 114 to the engaged position.

100321 In the extended position of the first linear actuator 138, the pin 149 of the worm screw 148 of the second linear actuator 122 may slide along the slot 152 from the first end 190 to the second end 192 without providing any resistance to the actuation of the first linear actuator 138. Similarly, the pin 149 of the coupling member 151 of the second linear actuator 122 may slide along the slot 152. The lever assemblies 124 may move to the second position during actuation of emergency brake system 130 in the retracted position of the second linear actuator 122. Thus, the lever assembly 124 of the present disclosure may allow the first linear actuator 138 to independently actuate the brake device 114 without any resistance from the second linear actuator 122.

[0033] FIG. 5 shows an arrangement of the lever assembly 124 in another operational configuration. The operational configuration, as illustrated in FIG. 5, may include actuation of the parking brake system 120 while the emergency brake system 130 is inactive. For actuating the parking brake system 120, the operator may actuate the electric switch 126. Upon actuation of the electric switch 126, the second linear actuator 122 may move towards the extended position. While moving towards the extended position, the second linear actuator 122 positioned at the first end 190 of the slot 152 may rotate the lever assemblies 124 to move to the second position. In the second position of the lever assembly 124, the link member 178 coupled to the second ami 174 may actuate the brake device 114 to the engaged position.

[0034] During the actuation of the second linear actuator 122, the telescopic arrangement 166 may extend in order to allow pivotal movement of the lever assemblies 124. Thus, the parking brake system 120 may actuate the lever assembly 124 to move the brake device 114 to the engaged position, Further, the lever assembly 124 may also enable actuation of the brake device 114 by the second linear actuator 122 irrespective of a position of actuation of the first linear actuator 138.

[0035] FIG. 6 shows an arrangement of the lever assembly 124 in yet another operational configuration. The operational configuration, as illustrated in FIG. 6, may correspond to an actuation of the parking brake system 120 while the emergency brake system 130 is active. The first linear actuator 138 may be in the extended position for the period till the accumulator 132 completely discharges the pressurized fluid stored therein, Hence, within the period of the extended position of the first linear actuator 138, the operator may actuate the electric switch 126 to actuate the parking brake system 120. When the electric switch 126 is ON, the electric motor t46 may actuate the worm screw 148 to move to the extended position. In the extended position, the pins 149 associated with the second linear actuator 122 may slide through the slots 152 of the lever assemblies 124 and reach the first point 190 of the slots 152. Thus, the second linear actuator 122 may retain the lever assemblies 124 in the engaged position thereof if the emergency brake system 130 is active or not active, 100361 While aspects of the present disclosure have been particularly shown and described with reference to the embodiments above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by the modification of the disclosed machines, systems and methods without departing from the spirit and scope of what is disclosed, Such embodiments should be understood to fall within the scope of the present disclosure as determined based upon the claims and any equivalents thereof

Claims

Claims What is claimed is: 1 A braking system for a machine, the braking system comprising a brake device configured to cause a braking force to be applied to the machine; a first linear actuator configured to be actuated from a retracted position to an extended position based on a first braking input; a second linear actuator configured to be actuated from a retracted position to an extended position based on a second braking input; and a lever assembly operatively coupled with the brake device, the lever assembly being configured for actuation by at least one of the first linear actuator and the second linear actuator so as to actuate the brake device, the lever assembly comprising: a base rotatable about an axis, the base defining a slot therein, wherein the second linear actuator is slidably received within the slot; a first arm extending from the base, the first arm being coupled to the first linear actuator; and a second arm extending from the base, the second arm being operatively coupled to the brake device; wherein actuation of the first linear actuator causes the lever assembly to rotate and actuate the brake device independently from the second linear actuator when the second linear actuator is in the retracted position, such that the slot of the base allows relative movement between the base and the second linear actuator.
2. The braking system of claim I, wherein the base is rotatably disposed on a pivot pin mounted on a frame of the machine.
3, The braking system of claim 1, wherein the lever assembly is actuated between a first position corresponding to a disengaged position of the brake device and a second position corresponding to an engaged position of the brake device.
4. The braking system of claim 3, wherein in the first position of the lever assembly, the second linear actuator is positioned adjacent to a first end of the slot.
5. The braking system of claim 3, wherein in the second position of the lever assembly based on actuation by the first linear actuator, the second linear actuator is positioned adjacent to a second end of the slot distal from the first end in the retracted position of the second linear actuator.
6. The braking system of claim 4, wherein the second linear actuator engages the first end of the slot to rotate the lever assembly based on an actuation of the second linear actuator to the extended position while the first linear actuator is in the retracted position.
7. The braking system of claim 1, wherein the second linear actuator comprises a pin to be slidably received within the slot.
8. The braking system of claim, wherein the first linear actuator is a hydraulic cylinder actuated by a machine hydraulic system.
9. The braking system of claim I, wherein the second linear actuator is a worm screw operated by an electric motor.
10. The braking system of claim 1, wherein the first linear actuator is coupled to a telescopic arrangement.
I I The braking system of claim 1, wherein the first braking input is provided by a depression of a brake pedal.
12. The braking system of claim, wherein the second braking input is a provided by an actuation of an electric switch.