JP4951436B2 - Clutch control device for hydraulic drive vehicle - Google Patents

Description

  The present invention relates to a clutch control device for a hydraulically driven vehicle that drives a vehicle with outputs of a plurality of variable displacement hydraulic motors.

  As this type of clutch control device, conventionally, after the displacement volume of one hydraulic motor becomes zero, the clutch connected to the hydraulic motor is disconnected, and the vehicle is driven only by the output of the other hydraulic motor. An apparatus is known (see, for example, Patent Document 1). The device described in Patent Document 1 disengages the clutch when the vehicle speed becomes a predetermined value or higher after the motor displacement becomes zero.

JP-A-11-230333

  However, although the displacement of the motor is not zero, the clutch may be turned off due to a clutch failure or the like. In this case, the total discharge amount of the hydraulic pump is applied to the light load side motor with the clutch turned off. Is supplied, the hydraulic motor may over-rotate.

A clutch control device for a hydraulically driven vehicle according to the present invention includes a hydraulic pump driven by an engine, a variable displacement first hydraulic motor connected to the hydraulic pump by a closed circuit and driven by pressure oil from the hydraulic pump, A variable displacement or fixed displacement second hydraulic motor connected in parallel to one hydraulic motor and driven by pressure oil from a hydraulic pump, and driven by outputs of the first hydraulic motor and the second hydraulic motor Driving drive shaft, a volume control device that controls the displacement of the first hydraulic motor from zero to the maximum displacement according to the load, and power transmission between the first hydraulic motor and the travel drive shaft A clutch device that connects or disconnects the path, and disconnects the power transmission path when the displacement of at least the first hydraulic motor is zero, and connects the power transmission path when it is greater than zero The clutch control means for controlling the clutch device so as to determine the disconnection of the power transmission path due to abnormal operation of the clutch apparatus, and the clutch control means to control the clutch apparatus so that the clutch control means connects the power transmission path. When the determination means determines that the power transmission path is disconnected, the rotation control means suppresses an increase in the rotation speed of the first hydraulic motor.
The clutch device is configured as a hydraulic clutch that operates by clutch control pressure, and pressure detection means for detecting the clutch control pressure is provided, and disconnection of the power transmission path is determined based on the clutch control pressure detected by the pressure detection means. You can also.
It is also possible to provide speed detection means for detecting the rotation speed of the first hydraulic motor, and to determine whether the power transmission path is disconnected based on the rotation speed detected by the speed detection means.
A determination unit that determines abnormality of the tilt control operation of the first hydraulic motor by the volume control device and a first hydraulic pressure by the determination unit when the clutch control unit controls the clutch device so as to disconnect the power transmission path. A rotation control means that suppresses an increase in the rotation speed of the first hydraulic motor when an abnormality in the tilt control operation of the motor is determined can be provided.
In this case, speed detection means for detecting the rotation speed of the first hydraulic motor is provided, and an abnormality in the tilt control operation of the first hydraulic motor is determined based on the rotation speed detected by the speed detection means. Also good.
The rotation control means may be configured as an engine rotation speed control means that limits the maximum rotation speed of the engine and suppresses an increase in the rotation speed of the first hydraulic motor.
The rotation control means can be configured as a pump control means that limits the upper limit of the displacement volume of the hydraulic pump and suppresses an increase in the rotation speed of the first hydraulic motor.
The rotation control unit may be configured as a motor control unit that suppresses an increase in the rotation speed of the first hydraulic motor by increasing a displacement volume of the first hydraulic motor.
The rotation control means may be configured as bypass means that bypasses the flow of pressure oil to the first hydraulic motor and suppresses an increase in the rotation speed of the first hydraulic motor.
An informing means for informing the determination result by the determining means can be further provided.

  According to the present invention, since the increase in the motor rotation speed is suppressed when the operation of the clutch device is abnormal or when the tilt control operation of the hydraulic motor is abnormal, it is possible to prevent over-rotation of the hydraulic motor.

Hereinafter, an embodiment of a clutch control device for a hydraulically driven vehicle according to the present invention will be described with reference to FIGS.
FIG. 1 is a travel hydraulic circuit diagram showing the configuration of the clutch control device according to the present embodiment. This clutch control device is applied to, for example, a wheel loader. A pair of hydraulic motors (a first motor 3 and a second motor 4) are connected in parallel to each other in parallel through the main pipes L1 and L2 to the hydraulic pump 2 driven by the engine 1 to form a so-called HST travel circuit. Has been. When the hydraulic motors 3 and 4 are rotated by the pressure oil from the hydraulic pump 2, the output torque of the hydraulic motors 3 and 4 is transmitted to the output shaft 6 through the gear box 5. As a result, the tire 8 rotates via the axle 7 and the vehicle travels.

  At this time, the output torque of the first motor 3 is input to the gear box 5 via the clutch device 15. The clutch device 15 is a hydraulic clutch that is operated by pressure oil (clutch pressure Pc) from the pressure reducing valve 22. That is, when the clutch pressure Pc of the predetermined value Pc1 or more acts from the pressure reducing valve 22 via the pipe line L3, the clutch device 15 is activated (turned on). As a result, the power transmission path between the first motor 3 and the output shaft 6 is connected, and the output torque of the first motor 3 is transmitted to the tire 8. On the other hand, when the clutch pressure Pc from the pressure reducing valve 22 becomes less than the predetermined value Pc1, the clutch device 15 is released (turned off). As a result, the power transmission path between the first motor 3 and the output shaft 6 is disconnected, and torque transmission from the first motor 3 to the output shaft 6 is interrupted.

  The pressure reducing valve 22 is an electromagnetic proportional pressure reducing valve, and the degree of pressure reduction, that is, the clutch pressure Pc is controlled by a control signal from the controller 10. That is, when a clutch-on signal is output from the controller 10, the clutch pressure Pc becomes equal to or higher than the predetermined value Pc1, and the clutch device 15 is turned on. When the clutch-off signal is output, the clutch pressure Pc becomes less than the predetermined value Pc1, and the clutch device 15 is turned off.

  The pressure oil from the hydraulic pump 20 driven by the engine 1 acts on the pressure reducing valve 22. A relief valve 21 is connected to the discharge side pipe L4 of the hydraulic pump 20, and the pressure Pp of the pipe L4 is set to the relief pressure Pp1 of the relief valve 21. Note that the pressure Pp is a primary pressure of the pressure reducing valve 22, and if the pressure Pp is equal to or higher than a predetermined value Pp1, a clutch pressure Pc equal to or higher than the predetermined value Pc1 can be supplied to the clutch device 15. On the other hand, when the pressure Pp is less than the predetermined value Pp1, the clutch pressure Pc higher than the predetermined value Pc1 cannot be supplied.

  In the HST travel circuit, a bypass circuit is formed so as to bypass the hydraulic motors 3 and 4, and a bypass valve 26 is provided in the bypass circuit L5. The bypass valve 26 is switched by a control signal from the controller 10. When the bypass valve 26 is switched to the position A, the main pipelines L1, L2 communicate with each other via the bypass valve 26, and when the bypass valve 26 is switched to the position B, the communication between the main pipelines L1, L2 is prevented.

  The controller 10 includes an operation amount detector 9a for detecting the operation amount of the accelerator pedal 9, a forward / reverse changeover switch 18 for instructing forward / backward movement of the vehicle, and an engine speed sensor 11 for detecting the engine speed (engine speed). And pressure sensors 12 and 13 for detecting the load pressure (motor drive pressure) of the HST circuit during forward and reverse travel, a vehicle speed sensor 14 for detecting the vehicle speed, and the rotational speed of the first motor 3 (motor rotational speed Nm). A signal from a motor speed sensor 23 for detecting the pressure, a pressure sensor 24 for detecting the primary pressure Pp acting on the pressure reducing valve 22, and a pressure sensor 25 for detecting the clutch pressure Pc acting on the clutch device 15 are respectively input. Based on these signals, the controller 10 outputs control signals to the pressure reducing valve 22, the bypass valve 26, and the alarm device 27, respectively.

  The hydraulic pump 2 is a variable displacement pump, and a pump tilt amount, that is, a pump displacement volume qp (pump capacity) is controlled by a tilt control device 2a. The tilt control device 2a includes a tilt cylinder and a forward / reverse switching valve that switches according to the operation of the forward / reverse switching switch 18. A control pressure is supplied to the tilting cylinder via the forward / reverse switching valve, and the pump tilting amount qp is controlled according to the control pressure, and the operation direction of the tilting cylinder according to the switching of the forward / backward switching valve. Is controlled, and the tilting direction of the hydraulic pump 2 is controlled.

  The control pressure increases in proportion to the increase in the engine speed, and the pump tilt amount qp increases as the control pressure increases. The engine speed is controlled according to the operation amount of the accelerator pedal 9. That is, the engine speed increases as the amount of operation of the accelerator pedal 9 increases. When the engine speed increases, both the rotational speed of the hydraulic pump 1 and the pump tilt amount increase, so that the pump discharge amount increases smoothly and responsively as the engine speed increases. Is obtained.

  The hydraulic motors 3 and 4 are all variable displacement motors, and the amount of motor tilt, that is, the motor displacement volume q1 and q2 (motor capacity) is controlled by the tilt control devices 3a and 4a, respectively. Control signals corresponding to the detection values of the pressure sensors 12 and 13 are output from the controller 10 to the tilt control devices 3a and 4a, respectively. 2A and 2B are diagrams showing examples of tilt control characteristics of the first motor 3 and the second motor 4, respectively. The horizontal axis represents the pressure on the high pressure side detected by the pressure sensors 12 and 13, that is, the HST driving pressure P, and the vertical axis represents the motor displacement volume q1 and q2.

  As shown in FIG. 2A, the displacement volume q1 of the first motor 3 is zero (q1 = 0) when the motor driving pressure (load pressure) P is within a predetermined value Pa or less, and the motor driving pressure P is predetermined. When the value Pa is exceeded, the value increases from 0 to the maximum q1max according to the load. When the displacement volume q1 becomes 0, the flow of pressure oil from the hydraulic pump 2 to the first motor 3 is blocked, and the rotation of the first motor 3 by the pump discharge oil is prevented.

  On the other hand, as shown in FIG. 2B, the motor displacement volume q2 of the second motor 4 is a minimum q2min (> 0) in the range where the motor driving pressure P is equal to or less than the predetermined value Pa, and the motor driving pressure P is a predetermined value. When it becomes Pa or more, it increases from the minimum q2min to the maximum q2max according to the load. In FIGS. 2A and 2B, in order to perform stable motor tilt control, the driving pressure P at the point where the displacement volume reaches the maximum q1max and q2max becomes larger than Pa by ΔP. However, in order to simplify the description, the following description will be made assuming that ΔP = 0.

  FIG. 3 is a diagram illustrating an example of clutch control according to the present embodiment. Characteristics f11 and f12 in FIG. 3 (a) show the relationship between the vehicle speed during acceleration operation and deceleration operation of the accelerator pedal 9 and the displacement volume q1 of the first motor 3, respectively, and characteristics f21 and f22 in FIG. 3 (b). Indicates the relationship between the vehicle speed during acceleration operation and deceleration operation of the accelerator pedal 9 and the displacement volume q2 of the second motor 4 respectively.

  FIG. 3 shows the characteristics when the accelerator pedal 9 is fully operated. As described below, the controller 10 outputs a clutch-off signal at the vehicle speed Voff during acceleration traveling, and outputs a clutch-on signal at the vehicle speed Von during deceleration traveling.

  When the vehicle is driven by depressing the accelerator pedal 9, the displacement volume q1 of the first motor 3 decreases as the travel load decreases as indicated by the characteristic f11. As a result, the vehicle speed increases, and the displacement volume q1 becomes zero at least when the vehicle speed Voff. When a clutch-off signal is output from the controller 10 at the vehicle speed Voff, the clutch device 15 is turned off and the first motor 3 is disconnected from the output shaft 6. Thereafter, the vehicle travels only by the driving torque of the second motor 4.

  As indicated by the characteristic f21, the displacement volume q2 of the second motor 4 during acceleration traveling is maintained at the maximum q2max until the vehicle speed becomes Voff. That is, when the vehicle speed is equal to or less than the clutch-off vehicle speed Voff, the displacement volume q2 is maintained at the maximum q2max regardless of the characteristics of FIG. When the vehicle speed exceeds Voff, the displacement volume q2 is controlled according to the travel load according to the characteristics of FIG. 2, and when the motor drive pressure P is smaller than Pa, the displacement volume q2 decreases to q2min. As a result, the vehicle speed increases, and traveling at high speed and low torque becomes possible.

  On the other hand, when the vehicle speed is decreased by decelerating the accelerator pedal 9 during traveling at the maximum vehicle speed or when the traveling load is increased, the displacement volume q2 of the second motor 4 is reduced from the minimum q2min as shown by the characteristic f22. Increase up to q2max. When the vehicle speed becomes Voff or less, the displacement volume q2 of the second motor 4 is maintained at the maximum q2max.

  During deceleration traveling, the displacement volume q1 is maintained at zero tilt regardless of the characteristics of FIG. 2 until the vehicle speed reaches Von. When the vehicle speed decreases to Von (<Voff) and a clutch-on signal is output from the controller 10, the clutch device 15 is turned on, and the first motor 3 and the output shaft 6 are connected. Thereafter, the displacement volume q1 of the first motor 3 is controlled according to the traveling load. When the motor driving pressure P is larger than Pa, the displacement volume q1 increases to q1max as shown by the characteristic f12. As a result, the vehicle speed decreases, and traveling at low speed and high torque becomes possible.

  In the present embodiment, the clutch is turned off at the vehicle speed Voff during acceleration traveling, so that it is possible to prevent the first motor 3 with zero tilt from rotating due to the rotation of the axle 6. As a result, running resistance is reduced, and engine output loss can be reduced. That is, torque (referred to as zero tilt loss torque) is also required to drive the zero tilt motor 3, but the zero tilt loss torque is suppressed by turning off the clutch after the zero tilt is reached. be able to.

  In this case, if the clutch device 15 is turned off after the displacement volume q1 becomes zero, the pump discharge oil does not flow to the first motor 3, and the rotation of the first motor 3 when the clutch is off can be prevented. On the other hand, if the clutch device 15 is turned off due to a failure of the clutch device 15, a failure of the pressure reducing valve 22, a failure of the first motor 3, etc., even though the displacement volume q 1 is not 0, all the pump discharge oil is on the light load side. Since it flows to the first motor 3, the first motor 3 may over-rotate when the clutch is off. In order to prevent this, in the present embodiment, the bypass valve 26 is controlled as follows.

  The controller 10 includes an arithmetic processing unit having a CPU, ROM, RAM, and other peripheral circuits. FIG. 4 is a flowchart illustrating an example of processing executed by the CPU of the controller 10. This flowchart is started by turning on an engine key switch, for example.

  In step S1, it is determined whether or not a clutch-on signal is output from the controller 10 to the clutch device 15. If the vehicle speed is Voff or less during acceleration traveling or if the vehicle speed is Von or less during deceleration traveling, a clutch-on signal is output to the pressure reducing valve 22, so step S1 is affirmed. If step S1 is affirmed, the process proceeds to step S2.

  In step S2, it is determined whether or not the pressure Pp in the pipe L4 detected by the pressure sensor 24 is equal to or higher than a predetermined value Pp1, that is, whether or not the primary pressure Pp1 that can turn on the clutch device 15 is generated. If the hydraulic pump 20 and the relief valve 21 are operating normally, Pp = Pp1, and in this case, step S2 is affirmed and the process proceeds to step S3. On the other hand, if there is an abnormality in either the hydraulic pump 20 or the relief valve 21, the pressure Pp in the pipe line L4 becomes less than the predetermined value Pp1. In this case, it is determined that the clutch device 15 is operating abnormally, and the process proceeds to step S6.

  In step S3, a clutch pressure Pc1 for turning on the clutch device 15 is generated in the pipe L3 in response to whether or not the clutch pressure Pc detected by the pressure sensor 25 is equal to or higher than a predetermined value Pc1, that is, a clutch-on signal. It is determined whether or not. If the pressure reducing valve 22 is operating normally, Pc = Pc1, and in this case, step S3 is affirmed and the process proceeds to step S4. On the other hand, if the pressure reducing valve 22 is abnormal, the clutch pressure Pc becomes less than the predetermined value Pc1. In this case, it is determined that the clutch device 15 is operating abnormally, and the process proceeds to step S6.

  In step S4, it is determined whether or not the rotational speed Nm of the first motor 3 detected by the speed sensor 23 is equal to or less than a predetermined value Nm1. The predetermined value Nm1 is set to, for example, the maximum allowable rotational speed of the motor 3. If the clutch device 15 is normal, the clutch device 15 is turned on by the clutch pressure Pc (= Pc1) from the pressure reducing valve 22. In this case, the rotation speed Nm is always equal to or lower than the predetermined value Nm1, and step S4 is affirmed and the process proceeds to step S5. On the other hand, if the clutch device 15 is out of order, the clutch device 15 may remain off even when the clutch pressure Pc reaches a predetermined value Pc1. In this case, the motor rotation speed Nm may exceed the predetermined value Nm1, and when Nm> Nm1, the clutch device 15 is abnormal in operation and the process proceeds to step S6.

  In step S5, a control signal is output to the bypass valve 26, and the bypass valve 26 is switched to position b. As a result, all the oil discharged from the hydraulic pump 2 can be supplied to the hydraulic motors 3 and 4 without passing through the bypass valve 26.

  In step S6, a control signal is output to the bypass valve 26, and the bypass valve 26 is switched to position a. As a result, part of the oil discharged from the hydraulic pump 2 passes through the bypass valve 26 and the amount of pressure oil supplied to the first motor 3 decreases. For this reason, when the operation of the clutch device 15 is abnormal, the number of rotations of the first motor 3 is reduced, and over-rotation of the motor 3 can be prevented.

  In step S7, a control signal is output to the alarm device 27 to activate the alarm device 27. For example, an alarm sound is generated for the operator by the operation of the alarm device 27, or an alarm display is output to a monitor in the cab. Thereby, the operator can recognize the operation abnormality of the clutch device 15 at an early stage, and can repair the abnormal part at an early stage.

  If it is determined in step S1 that the clutch-off signal is output, the process proceeds to step S4. In step S4, as described above, it is determined whether or not the motor rotation speed Nm is equal to or less than a predetermined value Nm1. If the first motor 3 is operating normally, the motor displacement q1 when the clutch-off signal is output is 0. In this case, Nm ≦ Nm1, so step S4 is affirmed and step S5 is entered. move on. On the other hand, if the first motor 3 or the tilt control device 3a is out of order, the displacement volume q1 may be larger than 0 even though the clutch-off signal is output. In this case, if Nm> Nm1, it is determined that the tilt control operation is abnormal, and the process proceeds to step S6.

A characteristic operation of the clutch control device according to the present embodiment will be described.
(1) At clutch-on signal output First, the operation when the displacement q1 of the first motor 3 is larger than 0 and the clutch-on signal is output from the controller 10 to the proportional valve 22 will be described. If all the parts such as the first motor 3, the tilt control device 3a, the hydraulic pump 20, the relief valve 21, the pressure reducing valve 22, and the clutch device 15 are operating normally, the clutch device 15 is turned on by the clutch-on signal. The bypass valve 26 is always switched to the position B (step S5). In this state, the oil discharged from the hydraulic pump 2 is distributed to the hydraulic motors 3 and 4, respectively, and the first motor 3 does not over-rotate.

  When the primary pressure Pp in the pipe line L4 becomes smaller than the predetermined value Pp1 due to a failure of the hydraulic pump 20 or the relief valve 21, the bypass valve 26 is switched to the position A (step S2 → step S6). When the clutch pressure Pc in the pipe line L3 becomes smaller than the predetermined value Pc1 due to a failure of the pressure reducing valve 22, the bypass valve 26 is switched to the position A (step S3 → step S6). At this time, since the clutch device 15 is turned off due to a decrease in the clutch pressure Pc, the discharge oil of the hydraulic pump 2 is preferentially supplied to the first motor 3 with a light load. However, by opening the bypass valve 26, the pump discharge Part of the oil bypasses the first motor 3 and flows through the pipe L5. Thereby, the supply amount of the pressure oil to the 1st motor 3 reduces, and the over rotation of the 1st motor 3 can be prevented.

  On the other hand, when the clutch device 15 is turned off due to the failure of the clutch device 15, the pump discharge oil flows preferentially to the first motor, and the motor rotation speed Nm increases. When the motor rotation speed Nm exceeds the predetermined value Nm1, the bypass valve 26 is switched to the position (a) (step S4 → step S6). As a result, the amount of pressure oil supplied to the first motor 3 is reduced, and over-rotation of the motor 3 due to a failure of the clutch device 15 can be prevented. Note that when the bypass valve 26 is switched to the position A, the alarm device 27 is activated, so that the operator can recognize the abnormality of the clutch device 15 at an early stage.

(2) When the clutch-off signal is output Next, the operation when the vehicle speed is Voff or more and the clutch-off signal is output from the controller 10 to the proportional valve 22 will be described. If all the parts such as the first motor 3 and the tilt control device 3a are operating normally, the displacement of the motor when the clutch is off is zero. For this reason, the flow of the pressure oil of the first motor 3 is blocked, and the rotation of the first motor 3 is prevented.

  On the other hand, when the clutch device 15 is turned on due to a failure of the first motor 3 or the tilt control device 3a, the pump discharge oil flows preferentially to the first motor 3, and the motor rotation speed Nm increases. When the motor rotation speed Nm exceeds the predetermined value Nm1, the bypass valve 26 is switched to the position (a) (step S4 → step S6). As a result, the amount of pressure oil supplied to the first motor 3 is reduced, and over-rotation of the first motor 3 due to an abnormal tilt control operation can be prevented.

According to the present embodiment, the following operational effects can be achieved.
(1) A bypass valve 26 is provided in the pipeline L5 that bypasses the hydraulic motors 3 and 4, and when the clutch-on signal is output, that is, when the motor displacement q1 is larger than 0, the pipeline for supplying the clutch pressure When the pressure Pp in L4 becomes smaller than the predetermined value Pp1, the bypass valve 26 is opened. As a result, the amount of pressure oil supplied to the first motor 3 is reduced, and over-rotation of the first motor 3 when the clutch device 15 is turned off due to a failure of the hydraulic pump 20 or the relief valve 21 can be prevented.

(2) When the clutch-on signal is output, the bypass valve 26 is opened when the clutch pressure Pc in the pipe L3 becomes smaller than the predetermined value Pc1. As a result, it is possible to prevent the first motor 3 from over-rotating when the clutch device 15 is turned off due to a failure of the pressure reducing valve 22.

(3) When the clutch-on signal is output, the bypass valve 26 is opened when the motor rotational speed Nm exceeds a predetermined value Nm1. As a result, the amount of pressure oil supplied to the first motor 3 is reduced, and over-rotation of the first motor 3 when the clutch device 15 is turned off due to a failure of the clutch device 15 itself can be prevented.

(4) When the clutch-off signal is output, the bypass valve 26 is opened when the motor rotation speed Nm exceeds a predetermined value Nm1. As a result, the amount of pressure oil supplied to the first motor 3 is reduced. Therefore, even if the displacement q1 of the motor is zero due to a failure of the hydraulic motor 3 or the tilt control device 3a, the overspeed of the first motor 3 is increased. Can be prevented.

(5) Since the alarm device 27 is also activated when the bypass valve 26 is opened, the operator recognizes the abnormal operation of the clutch device 15 and the abnormality of the tilt control operation of the first motor 3 at an early stage. Can prevent secondary damage from occurring.

  In the above embodiment, the bypass valve 26 is provided in the pipeline that bypasses the hydraulic motors 3 and 4, and the bypass valve 26 is opened at the time of abnormality determination to prevent over-rotation of the first motor 3. The configuration of the bypass means is not limited to this. Further, the rotation control means may be constituted by means other than the bypass valve 26. In this case, the bypass valve 26 is omitted, and instead of switching the bypass valve 26 to the position A in step S6 of FIG.

  For example, engine rotation speed control means for controlling the engine rotation speed may be provided, and the maximum rotation speed of the engine 1 may be limited when abnormality is determined to prevent the first motor 3 from over-rotating. Alternatively, the upper limit of the pump displacement volume qp may be limited by the tilt control device 2a serving as a pump control means at the time of abnormality determination to prevent the first motor 3 from over-rotating. Alternatively, the motor displacement means q1 may be increased (for example, controlled to the maximum tilt q1max) by the tilt control device 3a serving as the motor control means at the time of abnormality determination to prevent over-rotation of the first motor 3. .

  In the above embodiment, the abnormal operation of the clutch device 15 based on the pressures Pp and Pc detected by the pressure sensors 24 and 25 as pressure detecting means or the motor rotation speed Nm detected by the speed sensor 23 as speed detecting means. Although the abnormality of the tilt control operation of the first motor 3 is determined, the configuration of the determination means is not limited to this. For example, a flow rate sensor for detecting the flow rate of the first motor 3 is provided, and an abnormality is determined when a flow rate greater than 0 is detected by the flow rate sensor even though a clutch-off signal is output from the controller 10. May be. A tilt angle sensor for detecting the displacement volume q1 of the first motor 3 is provided, and an abnormality is detected when a displacement volume q1 greater than 0 is detected by the tilt angle sensor even though a clutch-off signal is output. You may judge. As long as the abnormality determination result is notified, any alarm device 27 may be used as the notification means.

  In the above embodiment, the first motor 3 (first hydraulic motor) connected to the clutch device 15 and the second motor 4 (second hydraulic motor) not connected to the clutch device 15 are provided one by one. However, there may be a plurality of first hydraulic motors and second hydraulic motors. Moreover, in the said embodiment, although the 2nd motor 4 as a 2nd hydraulic motor was made into the variable capacity type, a fixed capacity type may be sufficient. As a volume control device, the displacement volume q1 of the first motor 3 is controlled between 0 and q1max by a control signal from the controller 10, but the displacement volume q1 is hydraulically controlled according to the motor driving pressure P. Also good. Although the clutch device 15 is provided between the first motor 3 and the gear box 5, if the power transmission path between the first motor 3 and the driving shaft for traveling can be connected or disconnected, the arrangement of the clutch device 15 is provided. Is not limited to this.

  The clutch device is controlled by outputting a clutch-on signal and a clutch-off signal to the pressure reducing valve 22 according to the vehicle speed. However, the clutch is turned off at least when the displacement volume q1 of the first motor is 0, and the displacement volume q1 As long as the clutch is turned on when is greater than 0, the clutch control means may have any configuration. Therefore, the characteristic of the motor displacement volume q1 is not limited to that shown in FIG. Although the clutch is turned off at the vehicle speed Voff, the vehicle speed Voff may be changed according to the engine speed.

  The example in which the clutch control device of the present invention is applied to a wheel loader has been described above, but the present invention can be similarly applied to other hydraulically driven vehicles such as forklifts. That is, the present invention is not limited to the clutch control device of the embodiment as long as the features and functions of the present invention can be realized.

1 is a traveling hydraulic circuit diagram illustrating a configuration of a clutch control device according to an embodiment of the present invention. The figure which shows an example of the tilt control characteristic of the hydraulic motor of FIG. The figure which shows the one characteristic at the time of clutch control. The flowchart which shows an example of the process performed with the controller of FIG.

Explanation of symbols

2 Hydraulic pump 2a Tilt control device 3 First motor 3a Tilt control device 4 Second motor 6 Output shaft 10 Controller 15 Clutch device 22 Pressure reducing valve 23 Speed sensor 24, 25 Pressure sensor 26 Bypass valve 27 Alarm device

Claims (10)

A hydraulic pump driven by an engine;
A variable displacement first hydraulic motor connected to the hydraulic pump in a closed circuit and driven by pressure oil from the hydraulic pump;
A variable displacement or fixed displacement second hydraulic motor connected in parallel to the first hydraulic motor and driven by pressure oil from the hydraulic pump;
A travel drive shaft driven by outputs of the first hydraulic motor and the second hydraulic motor;
A volume control device for controlling a displacement of the first hydraulic motor between zero and a maximum displacement according to a load;
A clutch device for connecting or disconnecting a power transmission path between the first hydraulic motor and the driving shaft;
Clutch control means for controlling the clutch device to disconnect the power transmission path when the displacement of at least the first hydraulic motor is zero and to connect the power transmission path when larger than zero;
Determination means for determining disconnection of the power transmission path due to abnormal operation of the clutch device;
When the clutch control unit is controlling the clutch device to connect the power transmission path, if the determination unit determines that the power transmission path is disconnected, the rotational speed of the first hydraulic motor A clutch control device for a hydraulically driven vehicle. The clutch control device for a hydraulically driven vehicle according to claim 1,
The clutch device is a hydraulic clutch that operates by clutch control pressure,
The determination unit includes a pressure detection unit that detects the clutch control pressure, and determines whether the power transmission path is disconnected based on the clutch control pressure detected by the pressure detection unit. Clutch control device. The clutch control device for a hydraulically driven vehicle according to claim 1,
The determination means includes speed detection means for detecting a rotation speed of the first hydraulic motor, and determines whether the power transmission path is disconnected based on the rotation speed detected by the speed detection means. A clutch control device for a hydraulically driven vehicle. A hydraulic pump driven by an engine;
A variable displacement first hydraulic motor connected to the hydraulic pump in a closed circuit and driven by pressure oil from the hydraulic pump;
A variable displacement or fixed displacement second hydraulic motor connected in parallel to the first hydraulic motor and driven by pressure oil from the hydraulic pump;
A travel drive shaft driven by outputs of the first hydraulic motor and the second hydraulic motor;
A volume control device for controlling a displacement of the first hydraulic motor between zero and a maximum displacement according to a load;
A clutch device for connecting or disconnecting a power transmission path between the first hydraulic motor and the driving shaft;
Clutch control means for controlling the clutch device to disconnect the power transmission path when the displacement of at least the first hydraulic motor is zero and to connect the power transmission path when larger than zero;
Determination means for determining an abnormality in the tilt control operation of the first hydraulic motor by the volume control device;
When the clutch control unit is controlling the clutch device so as to disconnect the power transmission path, if the determination unit determines that the tilt control operation of the first hydraulic motor is abnormal, the first control unit A clutch control device for a hydraulically driven vehicle, comprising: a rotation control unit that suppresses an increase in the rotation speed of the hydraulic motor. The clutch control device for a hydraulically driven vehicle according to claim 4,
The determination means has speed detection means for detecting the rotation speed of the first hydraulic motor, and detects an abnormality in the tilt control operation of the first hydraulic motor based on the rotation speed detected by the speed detection means. A clutch control device for a hydraulically driven vehicle, characterized by: In the clutch control device of the hydraulic drive vehicle according to any one of claims 1 to 5,
The clutch control apparatus for a hydraulically driven vehicle, wherein the rotation control means includes engine rotation speed control means for limiting an increase in rotation speed of the first hydraulic motor by limiting a maximum rotation speed of the engine. In the clutch control device of the hydraulic drive vehicle according to any one of claims 1 to 5,
The clutch control device for a hydraulically driven vehicle, wherein the rotation control means includes pump control means for restricting an increase in rotational speed of the first hydraulic motor by limiting an upper limit of a displacement volume of the hydraulic pump. In the clutch control device of the hydraulic drive vehicle according to any one of claims 1 to 5,
The clutch control device for a hydraulically driven vehicle, wherein the rotation control means includes motor control means for increasing a displacement volume of the first hydraulic motor and suppressing an increase in a rotation speed of the first hydraulic motor. . In the clutch control device of the hydraulic drive vehicle according to any one of claims 1 to 5,
The clutch of the hydraulically driven vehicle, wherein the rotation control means includes a bypass means for bypassing the flow of pressure oil to the first hydraulic motor and suppressing an increase in the rotational speed of the first hydraulic motor. Control device. In the clutch control device of the hydraulic drive vehicle according to any one of claims 1 to 9,
A clutch control device for a hydraulically driven vehicle, further comprising notification means for notifying a determination result by the determination means.

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