JP5245381B2 - Hydraulic brake circuit - Google Patents

Description

  The present invention relates to a hydraulic brake circuit that is used in an industrial vehicle and receives hydraulic fluid supplied from a hydraulic fluid supply source to supply hydraulic fluid to a traveling brake and a parking brake.

Conventionally, in an industrial vehicle, many parking brakes are configured to receive an operation from a handle and transmit an operation force received by the handle via a wire cable to bring it into a braking state or to release the braking state. It has been used (see, for example, Patent Document 1). In addition, a parking brake that releases a braking state by receiving a hydraulic pressure supply from a hydraulic pressure supply source and enters a braking state when the hydraulic pressure supply is not received is also considered (see, for example, Patent Document 2). ).
JP 2007-22700 A JP 2006-125619 A

  However, in the parking brake using the wire cable as shown in Patent Document 1, it is necessary for the driver to operate the parking brake with the handle to bring the vehicle into a braking state when the vehicle is broken or the engine is stopped.

  Further, in the hydraulic parking brake as shown in Patent Document 2, a hydraulic pressure source different from the hydraulic pressure source of the traveling brake is used, and each of the traveling brake system and the parking brake system uses separate pipes. There are many cases. In such an embodiment, there is a problem that the overall structure becomes complicated. Further, in the hydraulic parking brake as shown in Patent Document 2, since it is necessary to constantly supply hydraulic pressure to the parking brake during traveling, there is a problem that a load is applied to the traveling engine of the vehicle.

  The present invention is configured to solve the problems described above.

That is, the hydraulic brake circuit according to the present invention is a hydraulic brake circuit for receiving hydraulic fluid supplied from a hydraulic fluid supply source that receives power from a vehicle engine and supplying hydraulic fluid to a traveling brake and a parking brake. A common hydraulic fluid supply path for supplying hydraulic fluid to the traveling brake and the parking brake, a hydraulic pressure sensor for detecting the hydraulic pressure in the common hydraulic fluid supply path, and the hydraulic pressure sensor A first state in which the hydraulic fluid supply source and the common hydraulic fluid supply path are connected to maintain the hydraulic pressure at a predetermined value or more based on the hydraulic pressure, and the hydraulic fluid from the hydraulic fluid supply source is recirculated without load. and switchable changeover valve between 2 states, characterized by comprising a means for suppressing the lowering of the common operating fluid provided in the supply passage hydraulic pressure in the common hydraulic fluid supply path.

  If this is the case, the hydraulic fluid is supplied to the traveling brake and the parking brake from one hydraulic fluid supply source through the common hydraulic fluid supply path, respectively, so that the traveling brake and the parking brake are operated separately. Compared with the mode in which the hydraulic fluid is supplied from the liquid supply source, the apparatus can be reduced in size and the configuration can be simplified. Further, when the hydraulic pressure in the common hydraulic fluid supply path is equal to or higher than a predetermined value and the switching valve is in the second state, the hydraulic fluid from the hydraulic fluid supply source is recirculated with no load to drive the hydraulic fluid supply source. Therefore, it is not necessary to apply a load to the engine, and the traveling brake is operated using the hydraulic pressure in the common hydraulic fluid supply path, and then the switching valve is set to the first state in response to the decrease in the hydraulic pressure. Since the hydraulic fluid can be supplied, a circuit for circulating the hydraulic fluid from the traveling brake can be omitted. From this point, the apparatus can be downsized and the configuration can be simplified.

  Further, a first state is provided between the common hydraulic fluid supply path and the parking brake, and connects the common hydraulic fluid supply path and the parking brake; the common hydraulic fluid supply path and the parking brake; And the second switching valve that can be switched between the second state in which the parking brake is connected to the tank is further provided unless the second switching valve is in the first state. Since the hydraulic fluid is not supplied from the hydraulic fluid supply path to the parking brake, for example, unless the operation indicating the intention to drive the vehicle is performed, the second switching valve is set to the second state to prevent the vehicle from malfunctioning. .

  According to the configuration of the hydraulic brake circuit according to the present invention, the hydraulic brake is supplied to the traveling brake and the parking brake from one hydraulic fluid supply source via the common hydraulic fluid supply path, respectively, so that the driving brake and the parking brake are supplied. Compared with a mode in which hydraulic fluid is supplied from a separate hydraulic fluid supply source to the brake, the apparatus can be downsized and the configuration can be simplified. Further, when the hydraulic pressure in the common hydraulic fluid supply path is equal to or higher than a predetermined value and the switching valve is in the second state, the hydraulic fluid from the hydraulic fluid supply source is recirculated with no load to drive the hydraulic fluid supply source. Therefore, it is not necessary to apply a load to the engine, and the brake for operation is operated using the hydraulic pressure in the hydraulic fluid supply source, and then the switching valve is set to the first state in response to the decrease in hydraulic pressure. Therefore, the circuit for circulating the hydraulic fluid from the traveling brake can be omitted. From this point, the apparatus can be downsized and the configuration can be simplified.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  The hydraulic brake device according to the present embodiment is used in an industrial vehicle that travels with power from an engine E. As schematically shown in FIG. 1, a hydraulic pump 1 that is a hydraulic fluid supply source and the hydraulic pump 1 The driving brake 2 that receives the hydraulic fluid supplied from the hydraulic pump 1, the parking brake 3 that receives the hydraulic fluid supplied from the hydraulic pump 1 to release the braking state, and the operation to release the parking brake 3 are received. A parking switch 4, a hydraulic brake circuit 5 that supplies hydraulic fluid from the hydraulic pump 1 to the traveling brake 2 and the parking brake 3, and a controller 6 that controls the hydraulic brake circuit 5 are provided. .

  The hydraulic pump 1 is supplied with power from the engine E and sends hydraulic fluid to the hydraulic brake circuit 5.

  The traveling brake 2 has the same configuration as a conventionally known hydraulic traveling brake as used in an industrial vehicle.

  The parking brake 3 also has substantially the same configuration as a conventionally known hydraulic traveling brake that is used for industrial vehicles. In other words, the parking brake 3 is in a braking state when it does not receive hydraulic pressure from the hydraulic brake circuit 5, and has a configuration that releases the braking state only after receiving hydraulic pressure from the hydraulic brake circuit 5.

  The parking switch 4 receives an operation for performing braking by the parking brake 3 and an operation for releasing the braking by the parking brake 3. Specifically, it is possible to switch between a braking state in which braking is performed by the parking brake 3 and a braking release state in which braking by the parking brake 3 is released.

  Accordingly, the hydraulic brake circuit 5 of the present embodiment detects a common hydraulic fluid supply path 51 that supplies hydraulic fluid to the traveling brake 2 and the parking brake 3 and the hydraulic pressure in the common hydraulic fluid supply path 51. A hydraulic pressure sensor 52 that connects the hydraulic fluid supply source and the common hydraulic fluid supply path to maintain the hydraulic pressure at or above a predetermined hydraulic fluid pressure based on the hydraulic pressure detected by the hydraulic pressure sensor 52. A first switching valve 53 that is a switching valve that can be switched between an ON state that is 1 state and an OFF state that is a second state in which the hydraulic fluid from the hydraulic fluid supply source is recirculated without load. Further, in the present embodiment, the hydraulic brake circuit 5 includes an ON state that is a first state in which the common hydraulic fluid supply path 51 and the parking brake 3 are connected, and the common hydraulic fluid supply path 51 and the parking brake 3. A second switching valve 55 that is switchable between an OFF state, which is a second state, for connecting the parking brake 3 and a discharge passage 57 toward the tank T to disconnect the hydraulic fluid toward the tank T, and When the pressure between the discharge port 1a of the hydraulic pump 1 and the first switching valve 53 exceeds a predetermined relief pressure, the discharge port 1a of the hydraulic pump 1 and the discharge passage 57 are communicated with each other. And a relief valve 58.

  The common hydraulic fluid supply path 51 includes a base 51a that reaches the branch 51x from the switching valve 53, a parking brake flow path 51b that extends from the branch 51x to the parking brake 3, and a travel that travels from the branch 51x to the travel brake 2. And a brake channel 51c. The fluid pressure inside the parking brake passage 51b and the traveling brake passage 51c is the same. The base 51a is provided with a check valve 54 for maintaining the pressure of the common hydraulic fluid supply passage 51.

  In the present embodiment, the hydraulic pressure sensor 52 is provided in the traveling brake flow path 51c, detects the hydraulic pressure in the common hydraulic fluid supply path 51, and outputs a corresponding hydraulic pressure signal to the control device.

  The first switching valve 53 communicates the discharge port 1a of the hydraulic pump 1 and the common hydraulic fluid supply path 51 in the ON state. On the other hand, in the OFF state, the discharge port 1a of the hydraulic pump 1 communicates with the discharge path 56 toward the tank T.

  In the present embodiment, the second switching valve 55 is turned on when the engine E is in operation and the parking switch 4 is in a braking release state, that is, when the operation for releasing the braking state is accepted. Take a state. On the other hand, when the engine E is not in operation and when the parking switch 4 is in a braking state even when the engine E is in operation, the OFF state is taken.

  As schematically shown in FIG. 2, the controller 6 mainly includes a microcomputer system including a central processing unit 61, a storage device 62, an input interface 63, and an output interface 64. The input interface 63 detects from an operation state signal a indicating whether or not the engine E is operating, a parking switch signal b indicating whether the parking switch 4 is in a braking state or a braking release state, and the pressure sensor 52. An input of a hydraulic pressure signal c indicating the hydraulic pressure is received. From the output interface 64, the first switching signal 53 for switching the first switching valve 53 between the first and second states is output to the first switching valve 53, and to the second switching valve 55. In contrast, a second switching signal f for switching the second switching valve 55 between the first and second states is output. In the storage device 62, the driving state signal a indicating that the engine E is operating and the parking switch 4 are released so that the braking by the parking brake 3 can be released only when there is an intention to drive the vehicle. When both the parking switch signal b indicating the state is received, the second switching signal f is output to set the second switching valve 55 to the first state, and in the other states, the second switching valve 55 is output. Is incorporated in a parking control program for controlling to output the second switching signal f so as to be in the second state. The controller 6 is a program that operates when the vehicle is operating, that is, when the second switching valve 55 is in an ON state, and maintains the hydraulic pressure in the common hydraulic fluid supply path 51 at or above the hydraulic pressure. Therefore, when the hydraulic pressure corresponding to the hydraulic pressure signal c from the hydraulic pressure sensor 52 falls below the hydraulic pressure, the first switching signal e is output to turn on the first switching valve 53, and Hydraulic pressure for controlling to output the first switching signal e to turn the first switching valve 53 off when the hydraulic pressure corresponding to the hydraulic pressure signal c from the hydraulic pressure sensor 52 exceeds the hydraulic pressure. An adjustment program is also built-in. The hydraulic fluid pressure is set near the relief pressure and at a lower pressure side than the relief pressure.

  The flow of control performed by the controller 6 according to the parking control program will be described below with reference to FIG. 3 which is a flowchart.

  First, it is determined whether or not the engine E is operating, that is, whether or not the operating state signal a indicating that the engine E is operating is output to the controller 6 (step S1).

  When the engine E is in operation, next, whether or not the parking switch 4 is in a brake release state, that is, whether or not a parking switch signal b indicating that the parking switch 4 is in a brake release state is output. Is determined (step S2).

  When the engine E is in operation and the parking switch 4 is in a brake release state, the second switching valve 55 is turned on (step S3).

  On the other hand, when the engine is not in operation or when the parking switch 4 is in the braking state even when the engine is in operation, the second switching valve 55 is turned off (step S4), and the process returns to step S1.

  When the second switching valve 55 is turned on, the following control is subsequently performed by the hydraulic pressure adjustment program. This control flow will be described below with reference to FIG. 4 which is a flowchart.

  First, whether or not the hydraulic pressure in the common hydraulic fluid supply path 51 is lower than the hydraulic pressure, specifically, the hydraulic pressure corresponding to the hydraulic pressure signal c output from the hydraulic pressure sensor 52 is lower than the hydraulic pressure. It is determined whether or not (step S5).

  When the hydraulic pressure in the common hydraulic fluid supply path 51 is lower than the hydraulic fluid pressure, control is performed to output the first switching signal e to turn on the first switching valve 53 (step S6). On the other hand, when the hydraulic pressure in the common hydraulic fluid supply path 51 is not lower than the hydraulic pressure, control is performed to output the first switching signal e so as to turn off the first switching valve 53 (step S7). .

  After the control by the hydraulic pressure adjustment program, the parking control program is executed again.

  While the engine E is in operation and the parking switch is in the brake release state, the hydraulic brake circuit 5 operates as follows under the control of the hydraulic pressure adjustment program.

  First, immediately after the parking switch 4 is switched to the ON state, the fluid pressure in the common hydraulic fluid supply path 51 is sufficiently lower than the hydraulic fluid pressure, so the first switching valve 53 is in the ON state, and the common hydraulic fluid supply path The hydraulic fluid is supplied to the traveling brake 2 and the parking brake 3 via 51.

  Thereafter, when the hydraulic pressure in the common hydraulic fluid supply path 51 exceeds the hydraulic pressure, the first switching valve 53 is turned off. At that time, the hydraulic fluid discharged from the hydraulic pump 1 circulates to the tank T with no load. On the other hand, the reduction of the hydraulic pressure in the common hydraulic fluid supply path 51 is suppressed by the action of the check valve 54.

  Thereafter, when the hydraulic pressure in the common hydraulic fluid supply passage 51 falls below the hydraulic fluid pressure, such as when the travel brake 2 is operated, the first switching valve 53 is turned on again, and the common hydraulic fluid supply passage 51 is turned on. The hydraulic fluid is supplied to the traveling brake 2 and the parking brake 3 via the. That is, when the hydraulic pressure in the common hydraulic fluid supply path 51 falls below the hydraulic pressure, the hydraulic fluid is supplied to the traveling brake 2 and the parking brake 3 as described above. Is maintained above the hydraulic fluid pressure.

  When the parking switch 4 is switched to the braking state or when the operation of the engine E is stopped, that is, when the driving of the vehicle is stopped, the second switching valve 55 is controlled under the control of the parking control program. Is in an OFF state. At that time, the hydraulic fluid is discharged from the parking brake 3 and the vehicle is braked by the parking brake 3.

  As described above, according to the configuration of the hydraulic brake circuit 5 according to the present embodiment, the hydraulic fluid is supplied from the single hydraulic pump 1 to the traveling brake 2 and the parking brake 3 via the common hydraulic fluid supply path 51. As a result, it is possible to reduce the size of the apparatus and to simplify the configuration, as compared with a mode in which hydraulic fluid is supplied to the traveling brake 2 and the parking brake 3 from separate hydraulic pumps. Further, when the hydraulic pressure in the common hydraulic fluid supply path 51 exceeds the hydraulic pressure, the first switching valve 53 is turned off, so that the hydraulic fluid from the hydraulic pump 1 is loaded with no load. It is no longer necessary to apply a load to the engine E for supplying the hydraulic fluid to the traveling brake 2 and the parking brake 3 by recirculation to T. In addition, it is possible to operate the traveling brake 2 using the hydraulic pressure in the common hydraulic fluid supply path 51, and then supply the hydraulic fluid by turning on the switching valve 53 in response to a decrease in hydraulic pressure. The circuit for circulating the hydraulic fluid from the traveling brake 2 can be omitted. From this point, the apparatus can be reduced in size and the configuration can be simplified.

  Further, an ON state is provided between the common hydraulic fluid supply path 51 and the parking brake 3, and connects the common hydraulic fluid supply path 51 and the parking brake 3, and the common hydraulic fluid supply path 51 and the parking brake 3 A second switching valve 55 that can be switched between an OFF state in which the parking brake 3 is disconnected is further provided, and the second switching valve is provided only when the engine E is in operation and the parking switch 4 is in a brake release state. 55 is set to the first state, so that the hydraulic fluid is not supplied from the common hydraulic fluid supply path 51 to the parking brake 3 unless the parking switch 4 is set to the brake release state during the operation of the engine E. Therefore, unless the operation indicating the intention to drive the vehicle is performed, the second switching valve 55 can be turned off to prevent the vehicle from malfunctioning.

  The present invention is not limited to the embodiment described above.

  For example, the second switching valve according to the above-described embodiment is omitted, and for example, an urging means for urging the brake position side in a state where the hydraulic pressure source does not receive the hydraulic pressure is provided in the parking brake. Alternatively, a configuration may be employed in which braking is released against the urging force of the urging means when the hydraulic pressure is received.

  Further, it is of course possible to connect a hydraulic fluid flow path for circulating the hydraulic fluid when it receives excessive hydraulic fluid pressure to the traveling brake.

  In the above-described embodiment, when the hydraulic pressure in the common hydraulic fluid supply path exceeds the hydraulic pressure, the first switching valve is turned off, and the hydraulic pressure in the common hydraulic fluid supply path falls below the hydraulic pressure. In this case, the control to turn on the first switching valve is performed, but the control described below may be performed.

  Specifically, when the first switching valve is in the OFF state, the control as described above, that is, when the hydraulic pressure in the common hydraulic fluid supply path exceeds the hydraulic pressure, the first switching valve is in the OFF state. When the hydraulic pressure in the common hydraulic fluid supply path is lower than the hydraulic fluid pressure, control is performed to turn on the first switching valve, and the first switching valve is in the ON state. The first switching valve is turned OFF when the hydraulic pressure in the common hydraulic fluid supply path exceeds the upper limit hydraulic pressure higher than the hydraulic pressure, and the hydraulic pressure in the common hydraulic fluid supply path is set to the upper limit. You may make it perform control which maintains a 1st switching valve in an ON state, when it falls below a hydraulic pressure.

  When such control is performed, when the first switching valve is in the ON state, even if the hydraulic pressure in the common hydraulic fluid supply path is equal to or higher than the hydraulic fluid pressure, the first switching valve is not changed unless the upper limit hydraulic pressure is exceeded. Since the switching valve is kept in the ON state, the hydraulic pressure in the common hydraulic fluid supply path can be more effectively maintained above the hydraulic pressure.

  In addition, various changes may be made without departing from the spirit of the present invention.

1 is a schematic diagram showing a hydraulic brake device using a hydraulic brake circuit according to an embodiment of the present invention. Schematic which shows the controller of the hydraulic brake apparatus which concerns on the same embodiment. The flowchart which shows the control which the controller of the hydraulic brake device concerning the embodiment performs. The flowchart which shows the control which the controller of the hydraulic brake device concerning the embodiment performs.

Explanation of symbols

DESCRIPTION OF SYMBOLS 3 ... Parking brake 5 ... Hydraulic brake circuit 51 ... Common hydraulic fluid supply path 52 ... Hydraulic pressure sensor 53 ... 1st switching valve (switching valve)
55. Second switching valve

Claims (2)

A hydraulic brake circuit for receiving hydraulic fluid supplied from a hydraulic fluid supply source that receives power from a vehicle engine and supplying hydraulic fluid to a traveling brake and a parking brake, the traveling brake and the parking brake A common hydraulic fluid supply passage for supplying hydraulic fluid to the hydraulic fluid, a hydraulic pressure sensor for detecting the hydraulic pressure in the common hydraulic fluid supply passage, and the hydraulic pressure exceeding a predetermined value based on the hydraulic pressure detected by the hydraulic pressure sensor Switchable between a first state in which the hydraulic fluid supply source is connected to the common hydraulic fluid supply path and a second state in which the hydraulic fluid from the hydraulic fluid supply source is recirculated without load. hydraulic brake circuit, characterized by comprising a valve and a means for suppressing a decrease in the common hydraulic fluid provided in the supply passage hydraulic pressure in the common hydraulic fluid supply path.   A first state, which is provided between the common hydraulic fluid supply path and the parking brake and connects the common hydraulic fluid supply path and the parking brake, and disconnects the common hydraulic fluid supply path and the parking brake. The hydraulic brake circuit according to claim 1, further comprising a second switching valve capable of switching between a second state in which the parking brake is connected to the tank.

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