JP2012086617A - Controller for small turning of articulated vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a controller for small turning of an articulated vehicle, in which a small turning brake mode is started by using an inexpensive circuit using an existing pump even when the articulated vehicle is not in a full-articulated state, and thereby dispensing with many operations of turning a steering wheel.SOLUTION: When performing the operations of turning the steering wheel so as to bend a front vehicle body relatively to a rear vehicle body in such a state that a small turning switch is turned on, the controller closes solenoid valves 56A, 56B to isolate a left brake circuit 41 from a right brake circuit 42, controls the relief pressure of an electromagnetic proportional relief valve 62 within a range from an unloaded state to the preset pressure according to an articulation angle to shift a priority valve 59, a flow rate from a pump 57 to a small turning pressure supply circuit 60 is made to take priority over that to a bucket working machine circuit 60a, controls the pressure of the small turning pressure supply circuit 60 on the basis of the electromagnetic proportional relief valve 62, and performs a control so that only a left small turning control valve 63 is opened when the articulated vehicle is turned to the left.

Description

  The present invention relates to a small turning control device in an articulated vehicle in which a front vehicle body is refractably connected to a rear vehicle body.

  FIG. 6 shows an articulated vehicle in which a front vehicle body 3 is refractably connected to a rear vehicle body 1 via an articulate shaft 2, and the rear vehicle body 1 includes a driver's seat 4, a rear wheel 5, and the like. The vehicle body 3 is a wheel loader including a bucket 6 and a front wheel 7.

  FIG. 7 shows a general brake circuit of this wheel loader. A left rear axle 12 and a right rear axle 13 are provided via a rear differential 11, and a left front axle 15 and a right front axle 16 are provided via a front differential 14. The brake pressure is supplied to the left wheel brake 17 provided on the left rear axle 12 and the left front axle 15 and the right wheel brake 18 provided on the right rear axle 13 and the right front axle 16, respectively. A stepping type brake master cylinder 19 is provided.

  When the vehicle operator depresses the brake pedal 19p, the brake master cylinder 19 acts to send hydraulic oil to the front and rear left wheel brakes 17 and the front and rear right wheel brakes 18, and the front and rear left and right wheel brakes 17 and 18 The hydraulic oil pressure is applied to the disc via a piston to apply a braking force.

  In such a brake circuit, the front and rear wheels on the inner side of the turn are braked (for example, in the case of counterclockwise rotation) so that a smaller turning radius can be obtained with respect to the smallest turning radius that is mechanically determined in a state where the vehicle body is refracted to the maximum. By applying the left wheel brake 17), a rotational speed difference is established between the turning outer wheel and the turning outer wheel faster than the inner wheel, and the braking force of this brake (left wheel brake 17) is controlled. Thus, there is a small turning type steering device in which the turning radius is controlled to the indicated value set by the turning radius command means (for example, see Patent Document 1).

Japanese Patent No. 3198402 (page 3-4, FIG. 1)

  The conventional small turning type steering device requires an expensive brake hydraulic circuit using a dedicated pump serving as a hydraulic power source for small turning, and the front vehicle body 3 is refracted to the maximum with respect to the rear vehicle body 1. In the articulated state, the inner wheel of the turn is brake controlled so as to have the instructed turning radius, so that many steering wheel turning operations are required.

  The present invention has been made in view of the above points, and is an inexpensive circuit that uses an existing pump in a small turning control device that makes a small turn by actuating a left or right wheel brake of an articulated vehicle. An object of the present invention is to provide a small turning control device in an articulated vehicle that does not require many steering wheel turning operations by activating the small turning brake mode even when not in a fully articulated state.

  According to the first aspect of the present invention, in an articulated vehicle in which a rear vehicle body and a front vehicle body are connected to each other through an articulate shaft so as to be able to be refracted, an articulate angle and a refraction direction of the front vehicle body refracted with respect to the rear vehicle body are detected. A brake master cylinder that supplies brake pressure to both the articulated angle sensor, the left wheel brake for braking the left wheel and the right wheel brake for braking the right wheel, and the working fluid discharged from the pump separately from the brake master cylinder Is supplied to one of the left wheel brake and the right wheel brake, another circuit using the above-mentioned pump in common with the small turning pressure supply circuit as a working fluid pressure source, and the flow rate to the small turning pressure supply circuit Priority valve that prioritizes the flow rate to one of the flow rate to the other circuit, and relief pressure in no load state By controlling the priority valve to a shift position that prioritizes the flow rate to other circuits, and controlling the priority valve in a direction to increase the relief pressure by an electric signal, the priority valve is controlled to reduce the flow rate to the small swivel pressure supply circuit. An electromagnetic proportional relief valve that pilot-controls the shift position to be increased and controls the pressure of the small turning pressure supply circuit according to the relief pressure, and a left that supplies the pressure controlled by the electromagnetic proportional relief valve to the left wheel brake as a brake pressure A small turning control valve, a right small turning control valve that supplies pressure controlled by an electromagnetic proportional relief valve to the right wheel brake as a brake pressure, and a small turning that supplies working fluid to only one of the left wheel brake and the right wheel brake A small-turn switch that selects the brake mode, and the front of the rear body with the small-turn switch on. If there is a handle turning operation that refracts the body, the relief pressure of the electromagnetic proportional relief valve is controlled according to the articulate angle within the range from no load to the set pressure, and the priority valve is shifted to make a small turn from the pump A small left turn corresponding to the inside of the turning direction detected by the articulate angle sensor while controlling the inner wheel brake pressure for small turning supplied to the pressure supply circuit according to the articulate angle detected by the articulate angle sensor. A small turning control device for an articulated vehicle including a controller having a function of starting a small turning brake mode for controlling either one of a control valve and a right small turning control valve in a valve open state.

  According to a second aspect of the present invention, the controller in the small turning control device for the articulated vehicle according to the first aspect includes a handle returning operation for returning the front vehicle body to the straight direction with respect to the rear vehicle body, and a brake master cylinder during the small turning operation. If there is at least one of the normal brake operations that supplies working fluid to the left wheel brake and the right wheel brake from the left wheel brake to the left wheel brake, the small turning brake mode is canceled and the left wheel brake is applied by the working fluid supplied from the brake master cylinder. And a function of operating a normal brake mode in which all wheel brakes of the right wheel brake can be applied.

  According to a third aspect of the present invention, in the small turning control device for an articulated vehicle according to the first or second aspect, a vehicle speed sensor for detecting a vehicle speed of the articulated vehicle and a side slip angle of the articulated vehicle are calculated. A yaw angular velocity sensor, and the controller cancels the small turning brake mode when the vehicle speed exceeds the vehicle speed threshold value and the side slip angle exceeds the side slip angle threshold value, and from the brake master cylinder. This is provided with a function of operating a normal brake mode in which all the wheel brakes of the left wheel brake and the right wheel brake can be used by the supplied working fluid.

  According to a fourth aspect of the present invention, there is provided a small turning control apparatus for an articulated vehicle according to any one of the first to third aspects, wherein the bucket working machine operates another bucket working machine mounted on the front vehicle body. It is a circuit.

  According to the first aspect of the present invention, when the small turning switch for selecting the small turning brake mode for supplying the working fluid to only one of the left wheel brake and the right wheel brake of the articulate vehicle is on, When there is a steering wheel turning operation that refracts the front car body, the controller shifts the priority valve via the electromagnetic proportional relief valve, and the articulated angle sensor detects the inner ring brake pressure for small turning from the pump to the small turning pressure supply circuit. Control is performed according to the detected articulate angle, and one of the left small turning control valve and the right small turning control valve corresponding to the inside of the turning direction detected by the articulate angle sensor is controlled to be in the valve open state. Therefore, even if it is not in a fully articulated state, the small turning brake mode can be activated. And eliminates many of the handle turning operation of the vehicle operator, is capable of vehicle tail swing with a small swing operation, it reduces the effort.

  At that time, the controller controls the relief pressure of the electromagnetic proportional relief valve within the range from the no-load state to the set pressure according to the articulate angle and shifts the priority valve, so that the pump turns the small swing pressure supply circuit. Since the supplied inner wheel brake pressure for small turning is controlled according to the articulate angle detected by the articulate angle sensor, the small turning inner wheel brake torque is controlled according to the body refraction angle of the front vehicle body with respect to the rear vehicle body. Smooth turning behavior can be obtained, and good ride comfort can be obtained.

  In addition, an inexpensive circuit that makes effective use of existing pumps is configured, and when a small turn is required, the required pressure for the inner ring brake for small turning is obtained by shifting the priority valve using an electromagnetic proportional relief valve. Therefore, compared with the case where a dedicated brake pump is employed, energy saving and low cost can be achieved.

  According to the second aspect of the invention, when there is at least one of a handle returning operation for returning the front vehicle body to the straight direction with respect to the rear vehicle body and a normal brake operation for applying the all-wheel brake, the small turning brake mode is canceled. Since the normal brake mode is operated, the normal brake mode is prioritized over the small turning brake mode, and high reliability for the brake system can be secured.

  According to the invention of claim 3, the controller cancels the small turning brake mode and the normal brake mode when the vehicle speed exceeds the vehicle speed threshold value and when the side slip angle exceeds the side slip angle threshold value. Therefore, the small turning brake control is automatically disabled when the vehicle body is unstable, and the stability of the vehicle body can be ensured.

  According to the fourth aspect of the present invention, the flow rate to the small turning pressure supply circuit that supplies the working fluid discharged from the pump separately from the brake master cylinder to one of the left wheel brake and the right wheel brake, and the bucket work machine circuit The priority valve that prioritizes the flow rate to one of the flow rates is used to supply the flow rate from the pump to the small swirl pressure supply circuit without performing a complete flow rate switch. Even during the operation, the bucket work machine can be operated by supplying a flow rate to the bucket work machine circuit at the same time, and the bucket work can be performed while making a small turn.

1 is a circuit diagram showing an embodiment of a small turning control device in an articulated vehicle according to the present invention. FIG. It is a block diagram which shows the relationship between the controller and sensor of a control apparatus same as the above. It is a top view of the articulate vehicle carrying a control device same as the above. It is a flowchart which shows an example of the control procedure by the controller of a control apparatus same as the above. It is a circuit diagram which shows the left small turning state of a control apparatus same as the above. It is a top view of an articulate vehicle. It is a circuit diagram of the brake circuit mounted in the conventional articulate vehicle.

  Hereinafter, the present invention will be described in detail based on one embodiment shown in FIGS.

  1 to 3 show hardware, and FIG. 3 shows an articulated vehicle in which a front vehicle body 23 is refractably connected to a rear vehicle body 21 via an articulate shaft 22. The front vehicle body 23 is a wheel loader including a bucket work machine 26, a front wheel 27, and the like. The bucket working machine 26 moves the bucket 26b up and down by a lift cylinder 26a as a working machine cylinder, and tilts the bucket 26b by a tilt cylinder 26c as a working machine cylinder. V is the vehicle speed of the articulated vehicle, α is the articulate angle of the front vehicle body 23 (ie, the vehicle body refraction angle) refracted with respect to the rear vehicle body 21, and β is the side slip angle of the articulated vehicle.

  FIG. 1 shows a small turning control device in this articulated vehicle, and left and right rear wheels 25 and front wheels 27 are provided with rotation speed sensors 28 for detecting their rotation speeds. The rear vehicle body 21 is provided with a left rear axle 32 and a right rear axle 33 via a rear differential 31, and the front vehicle body 23 is provided with a left front axle 35 and a right front axle 36 via a front differential 34. Yes.

  The left rear axle 32 and the left front axle 35 are respectively provided with left wheel brakes 37 and 38 for braking left wheels, and the right rear axle 33 and the right front axle 36 are provided with right wheel brakes 39 and 40 for braking right wheels. Each is provided. The left wheel brakes 37 and 38 and the right wheel brakes 39 and 40 have brake pistons P mounted on the vehicle body side so as to face the brake disc D mounted integrally on the axles 32, 33, 35, and 36, respectively. Each is provided to be able to advance and retreat.

  The piston chambers of the brake pistons P of the left wheel brakes 37 and 38 are communicated by a left brake circuit 41, and the piston chambers of the brake pistons P of the right wheel brakes 39 and 40 are communicated by a right brake circuit 42.

  A foot-operated brake master cylinder 51 that supplies brake pressure to all of the left wheel brakes 37 and 38 and the right wheel brakes 39 and 40 is installed. The brake master cylinder 51 discharges hydraulic oil (brake oil) as working fluid in the cylinder to the passages 54A and 54B by a stepping operation (normal brake operation) of a brake pedal 53 that is installed opposite to the tip of the piston rod 52. Then, hydraulic oil is supplied to the left brake circuit 41 and the right brake circuit 42 through electromagnetic valves 56A and 56B interposed in the passages 54A and 54B. The shortage due to leakage of hydraulic oil is replenished from the oil tank 55.

  The stepping operation by the brake pedal 53 is detected by a switch 53s such as a limit switch. The switch 53s functions as a trigger for detecting the depression of the brake pedal 53 during a small turn and releasing the small turn brake mode.

  The solenoid valves 56A and 56B provided in the passages 54A and 54B open the passages 54A and 54B as shown in FIG. 1 in the spring return position when the power supply connected to the solenoids a and b is off. At the power-on switching position, the valve 54 is closed and the passages 54A and 54B are closed to shut off the left brake circuit 41 and the right brake circuit 42 as shown in FIG.

  In addition to the brake master cylinder 51, a pump 57 that is driven by an in-vehicle engine (not shown) and sucks and discharges hydraulic oil from an oil tank 55 is installed, and a priority valve 59 is provided in a discharge passage 58 of the pump 57.

  The priority valve 59 has a flow rate to the small turning pressure supply circuit 60 for supplying the hydraulic oil discharged from the pump 57 to one of the left wheel brakes 37, 38 and the right wheel brakes 39, 40, and the small turning pressure supply circuit 60. And the flow rate to the bucket working machine circuit 60a as another circuit using the above-described pump 57 as the working fluid pressure source, that is, the working hydraulic pressure source, giving priority to the flow rate to either one, and switching completely is not. That is, even when the flow rate and pressure to one of the small turning pressure supply circuit 60 and the bucket work machine circuit 60a are maximized, the flow rate and pressure to the other circuit are not reduced to zero, Ensure that flow and pressure remain in the circuit.

  The bucket working machine circuit 60a is a hydraulic circuit of an implement system that operates a lift cylinder 26a that moves the bucket working machine 26 mounted on the front vehicle body 23 up and down, a tilt cylinder 26c that tilts up and down, and the like.

  When the spool 59a is shifted to the right as shown in FIG. 1, the priority valve 59 preferentially supplies a large flow rate to the bucket working machine circuit 60a and supplies a small flow rate to the small swirl pressure supply circuit 60. When the spool 59a is shifted to the left as shown in FIG. 5, a high flow rate is preferentially supplied to the small turning pressure supply circuit 60 and a small flow rate is supplied to the bucket working machine circuit 60a. .

  In the priority valve 59, the left side and the right side of the spool 59a are respectively connected to the small turning pressure supply circuit 60 by a pilot line 59p having orifices 59r1 and 59r2, and the spool 59a is a spring provided on the right side thereof. It is urged to the left by 59s. The biasing pressure of the spring 59s is about 0.3 MPa.

  A built-in relief valve 59c is connected to the right side of the spool 59a through a built-in filter 59b, and an external relief valve circuit 60b is connected through an orifice 59r3. The relief valve circuit 60b is provided with a pressure sensor 61 that detects the pressure of the relief valve circuit 60b, and an electromagnetic proportional relief valve 62 that controls the pressure of the relief valve circuit 60b to an adjustable relief pressure. .

  This electromagnetic proportional relief valve 62 can arbitrarily adjust the relief pressure of the relief valve circuit 60b by a relief valve setting knob 70 (FIG. 2) that can be operated from the no-load state (approximately 0 MPa) in the driver's seat according to the input electric signal. Proportional control is possible up to the set pressure that can be made, and the flow rate of the spool 59a of the priority valve 59 to the bucket working machine circuit 60a is controlled by controlling the relief pressure to a no-load state (approximately 0 MPa) as shown in FIG. Is controlled in a direction to increase the relief pressure toward an adjusted set pressure (for example, 5 MPa) by an electric signal as shown in FIG. The spool 59a is pilot controlled to a shift position that increases the flow rate to the small turning pressure supply circuit 60, and the pressure of the small turning pressure supply circuit 60 is reduced. And controlled in accordance with the full pressure, when setting the relief pressure for example 5MPa is controlled so as to increase the pressure of the small turning pressure supply circuit 60 to 5.3MPa (5MPa + 0.3MPa).

  The small turning pressure supply circuit 60 is branched into a left small turning passage 60A and a right small turning passage 60B via a pressure sensor 61a that detects the pressure of the hydraulic oil supplied to the small turning pressure supply circuit 60. The left small turning passage 60A is provided with an electromagnetic left small turning control valve 63 that supplies the pressure controlled by the electromagnetic proportional relief valve 62 to the left wheel brakes 37 and 38 as a brake pressure. In the passage 60B, there is provided an electromagnetic right small turning control valve 64 for supplying the pressure controlled by the electromagnetic proportional relief valve 62 to the right wheel brakes 39 and 40 as a brake pressure.

  The left small turning control valve 63 and the right small turning control valve 64 are, in the spring return state shown in FIG. 1 when the power connected to the solenoids A and B is turned off, the left small turning passage 60A or the right small turning control valve 64. When the valve connected to the solenoids A and B is turned on and the valve is switched when the power supply connected to the solenoids A and B is turned on, the valve is opened to open the left small turning passage 60A or the right small turning passage 60B. It becomes.

  As shown in FIG. 2, the vehicle operator has a small turning brake mode in which hydraulic oil is supplied to only one of the switch 53s, the pressure sensors 61 and 61a, the left wheel brakes 37 and 38, and the right wheel brakes 39 and 40. Detects a vehicle speed V of an articulated vehicle, a small turning switch 69 installed in a place where the operation can be easily selected, a relief valve setting knob 70 capable of setting and operating the set pressure of the electromagnetic proportional relief valve 62 at the driver's seat A vehicle speed sensor 71, an articulate angle sensor 72 for detecting the articulated angle (ie, the vehicle body refraction angle) α and the refraction direction of the front vehicle body 23 refracted with respect to the rear vehicle body 21, and a side slip angle β of the articulated vehicle (vehicle speed) A yaw angular velocity sensor 73 for calculating the angle between the vector and the direction of the front vehicle body 23) is connected to the signal input side of the controller 74.

  The vehicle speed sensor 71 is installed at a position where the rotational speed can be detected by the output shaft of the axle drive reduction gear connected to the hydraulic pump / hydraulic motor system, and the articulate angle sensor 72 is installed around the articulate shaft 22. The yaw angular velocity sensor 73 uses a gyro sensor around a vertical axis installed in the vehicle.

  The output side of the controller 74 is connected to the solenoid A of the left small turning control valve 63, the solenoid B of the right small turning control valve 64, the solenoids a and b of the electromagnetic valves 56A and 56B, and the solenoid E of the electromagnetic proportional relief valve 62. Yes.

  This controller 74 closes the electromagnetic valves 56A and 56B and closes the left brake circuit as shown in FIG. 5 when there is a steering wheel turning operation that refracts the front vehicle body 23 with respect to the rear vehicle body 21 with the small turn switch 69 turned on. 41 and the right brake circuit 42 are cut off, and the relief pressure of the electromagnetic proportional relief valve 62 is set in accordance with the articulate angle α within a range from a no-load state (0 MPa) to a set pressure (for example, 5 MPa) (ie, The articulated angle detected by the articulate angle sensor 72 for the small turning inner wheel brake pressure supplied from the pump 57 to the small turning pressure supply circuit 60 by shifting the spool 59a of the priority valve 59. The left small turning control valve 63 corresponding to the inside of the turning direction detected by the articulate angle sensor 72 is controlled in accordance with α (that is, proportionally). (In the left small turning state of FIG. 5 left small swing control valve 63) either one of the fine right tail swing control valve 64 has a function to activate the small swing radius brake mode control to the opened state.

  Further, in the small turning brake mode selected by turning on the small turning switch 69, the controller 74 performs a handle returning operation for returning the front vehicle body 23 to the straight direction with respect to the rear vehicle body 21, and the left wheel from the brake master cylinder 51 during the small turning. When there is at least one of normal brake operations for supplying hydraulic oil to all brakes of the brakes 37 and 38 and the right wheel brakes 39 and 40, the small turning brake mode is canceled and the hydraulic oil supplied from the brake master cylinder 51 Thus, a function of operating a normal brake mode that enables the left wheel brakes 37 and 38 and the right wheel brakes 39 and 40 to be applied to all wheels is provided.

  At this time, the controller 74 restores the spool 59a of the priority valve 59 by controlling the relief pressure of the electromagnetic proportional relief valve 62 to a no-load state (0 MPa) as shown in FIG. Prioritize the flow rate from 58 to the bucket work machine circuit 60a.

  Further, the controller 74 activates the small turning brake mode when the small turning switch 69 is ON when the vehicle speed V of the articulated vehicle is lower than the vehicle speed threshold and the side slip angle β is lower than the side slip angle threshold. However, when the vehicle speed V exceeds the vehicle speed threshold and when the side slip angle β exceeds the side slip angle threshold, the small turning brake mode is canceled and the brake master cylinder 51 starts. The supplied hydraulic oil has a function of operating a normal brake mode in which all wheel brakes of the left wheel brakes 37, 38 and the right wheel brakes 39, 40 can be used. Both the small right turn control valve 64 are controlled to be closed.

  The side slip angle β is calculated by the controller 74 by a known calculation method using the vehicle speed V detected by the vehicle speed sensor 71, the yaw angular velocity detected by the yaw angular velocity sensor 73, and the like.

  Next, the functions of the priority valve 59 and the electromagnetic proportional relief valve 62 will be described with reference to the changes in FIGS.

  The priority valve 59 basically shifts the spool 59a to the left side as shown in FIG. 5 by the biasing pressure of the spring 59s installed only on the right side of the spool 59a, and supplies a small turning pressure on the priority side. The hydraulic oil from the pump 57 is supplied to the circuit 60.

  In this state, the small turning inner wheel brake pressure of the small turning pressure supply circuit 60 acting on the left side surface of the spool 59a causes the relief pressure (for example, 5 MPa) of the electromagnetic proportional relief valve 62 acting on the right side surface of the spool 59a and the spring 59s. When it becomes higher than the sum (for example, 5.3 MPa) with the urging pressure (for example, 0.3 MPa), the spool 59a shifts to the right as shown in FIG. 1, and the hydraulic oil from the pump 57 is transferred to the bucket work machine circuit. Since it is preferentially supplied to 60a, the small turning inner wheel brake pressure of the small turning pressure supply circuit 60 rises to 5.3 MPa, but does not increase any more.

  On the other hand, the small turning inner wheel brake pressure of the small turning pressure supply circuit 60 acting on the left side surface of the spool 59a is applied by the relief pressure (for example, 5 MPa) of the electromagnetic proportional relief valve 62 acting on the right side surface of the spool 59a and the spring 59s. When it becomes lower than the sum (for example, 5.3 MPa) with the bias pressure (for example, 0.3 MPa), the spool 59a shifts to the left as shown in FIG. Return to.

  By repeating such an operation, the small turning inner wheel brake pressure of the small turning pressure supply circuit 60 is maintained at a substantially constant pressure of about 5.3 MPa.

  When such a priority valve 59 is used in a small turning system, as shown in FIG. 1, when the small turning is not performed or when the handle is returned after the small turning, the current value supplied to the electromagnetic proportional relief valve 62 is set to zero. As a result, the spool 59a is shifted to the right as shown in FIG. 1 so that no pressure is generated in the relief valve circuit 60b (relief pressure: 0 MPa). It is preferentially supplied to the work machine circuit 60a and used in the lift operation and tilt operation of the bucket work machine 26.

  At this time, the total flow rate of the hydraulic oil discharged from the pump 57 is not supplied to the bucket working machine circuit 60a, but there is also a flow rate supplied to the small turning pressure supply circuit 60 via the spool 59a of the priority valve 59, When a residual pressure slightly higher than the biasing pressure of the spring 59s (for example, 0.3 MPa) is generated in the small turning pressure supply circuit 60, the pilot pressure (relief pressure: 0 MPa) acting on the right side surface of the spool 59a and the spring 59s Since the residual pressure acting on the left side surface of the spool 59a is larger than the sum of the urging pressures (for example, 0.3 MPa), the shift state of the spool 59a shown in FIG. 1 is maintained.

  On the other hand, when making a small turn as shown in FIG. 5, a current corresponding to the articulate angle is applied to the electromagnetic proportional relief valve 62, and the set pressure set by the relief valve setting knob 70 operable at the driver's seat is set. Within the range, a relief pressure corresponding to the articulate angle required for small turning is generated in the relief valve circuit 60b.

  Next, the control procedure and operation of the hardware shown in FIGS. 1 to 3 will be described with reference to FIGS.

  FIG. 4 shows an example of the calculation procedure of the controller 74. Note that the circled numbers in FIG. 4 indicate step numbers.

(Step 1)
It is determined whether the small turning switch 69 is on or off.

(Step 2)
When the small turning switch 69 is off, the next normal brake mode is activated.

  That is, as shown in FIG. 1, the power of the solenoid A of the small left turn control valve 63 and the solenoid B of the right small turn control valve 64 are controlled to be off, and the small left turn control valve 63 and the right small turn control valve 63 are controlled. The control valve 64 is controlled to the spring return position, that is, the valve closed position, the solenoids a, b of the solenoid valves 56A, 56B are turned off, and the solenoid valves 56A, 56B are controlled to the spring return position, that is, the valve open position. To do. With these controls, the brake hydraulic fluid can be supplied simultaneously from the brake master cylinder 51 of the stepping operation type of the vehicle operator to the left wheel brakes 37 and 38 and the right wheel brakes 39 and 40.

  At this time, the solenoid E of the electromagnetic proportional relief valve 62 is controlled to be turned off, and the relief pressure of the relief valve circuit 60b is controlled to 0 MPa, so that the spool 59a of the priority valve 59 is connected to the pump shown in FIG. Shift to a position where priority is given to the flow rate from 57 to the bucket work machine circuit 60a, and maintain a low residual pressure in the small turning pressure supply circuit 60 that slightly exceeds the biasing pressure of the spring 59s (eg, 0.3 MPa). To do.

(Step 3)
When the small turning switch 69 is on, the vehicle operator sets the set pressure of the electromagnetic proportional relief valve 62 to an arbitrary value (for example, 5 MPa) by the relief valve setting knob 70, so that the small turning is made within the set pressure range. A relief pressure proportional to the required articulate angle α is obtained.

(Step 4)
The vehicle speed V is detected by the vehicle speed sensor 71, the articulate angle α is detected by the articulate angle sensor 72, and the side slip angle β is calculated from the vehicle speed V, the yaw angular velocity, and the like.

(Step 5)
A refraction state such as a turning direction is determined from the articulate angle α.

(Step 6)
Based on the presence or absence of a detection signal from the switch 53s, it is determined whether or not a stepping operation by the brake pedal 53, that is, a normal braking operation has been performed, in other words, whether or not the brake pedal 53 is in a non-operating state. If yes (NO), return to Step 2.

  That is, when there is a normal brake operation in which the brake pedal 53 is depressed during a small turn, the controller 74 uses the switch 53s as a trigger to release the small turn brake mode and the hydraulic oil supplied from the brake master cylinder 51 in step 2 Thus, a function of operating a normal brake mode in which all wheel brakes of the left wheel brakes 37 and 38 and the right wheel brakes 39 and 40 can be used is provided.

(Step 7)
When the brake pedal 53 is not operated (step 6 YES), it is determined by the articulate angle sensor 72 whether or not the steering handle 22H of the vehicle is being turned. Including the case where the steering wheel 22H is returned, the routine returns to step 2 to enter the normal brake mode in which the all-wheel brake can be applied.

(Step 8)
When the steering handle 22H of the vehicle is turned, it is determined whether or not the vehicle speed V detected using the vehicle speed sensor 71 exceeds a vehicle speed threshold value (for example, 10 km / h). If the vehicle speed V exceeds the vehicle speed threshold value, a small turn at high speed is not preferable, so the same command as when the steering wheel is returned is issued (return to step 2).

  As a result, when the vehicle speed V exceeds the vehicle speed threshold, brake pressure can be supplied from the brake master cylinder 51 to the all-wheel brakes 37, 38, 39, 40, but the left small turning control valve 63 and the right Since both the small turning control valves 64 are controlled to be closed, the brake pressure cannot be supplied from the pump 57 only to the left wheel brakes 37, 38 or only to the right wheel brakes 39, 40.

(Step 9)
It is determined whether or not the side slip angle β exceeds a side slip angle threshold (for example, 30 °). When the side slip angle β exceeds the side slip angle threshold value, the process returns to step 2 in the same manner, and brake pressure can be supplied from the brake master cylinder 51 to all the wheel brakes 37, 38, 39, 40. Since both the turning control valve 63 and the right small turning control valve 64 are controlled to be closed, it is not possible to supply brake pressure from the pump 57 only to the left wheel brakes 37 and 38 or only to the right wheel brakes 39 and 40.

(Step 10)
In the controller 74, the small turning switch 69 is turned on, the brake pedal 53 is not operated, the steering handle 22H of the vehicle is turned, the vehicle speed V is lower than the vehicle speed threshold, and the side slip angle β is When it is lower than the side slip angle threshold value, it is determined whether or not the articulated vehicle is in a counterclockwise posture as shown in FIG.

(Step 11)
In the case of counterclockwise rotation, the next counterclockwise small turning brake mode is activated.

  That is, the solenoid A of the left small turning control valve 63 is turned on to control the left small turning control valve 63 to the switching position shown in FIG. 5, that is, the valve open position, while the right small turning control valve is controlled. The solenoid B of the valve 64 is kept turned off, the small right turn control valve 64 is maintained at the spring return position, that is, the valve closed position, and the solenoids a and b of the solenoid valves 56A and 56B are turned on. Thus, the electromagnetic valves 56A and 56B are controlled to the switching position, that is, the valve closed position. By these controls, as shown in FIG. 5, the left brake circuit 41 and the right brake circuit 42 are disconnected, and hydraulic oil can be supplied from the small turning pressure supply circuit 60 to the left wheel brakes 37 and 38. At the same time, the supply of hydraulic oil to the right wheel brakes 39, 40 is shut off.

  At the same time, when the articulate angle α detected by the articulate angle sensor 72 is not more than a threshold value (for example, 25 °), the power supply of the solenoid E of the electromagnetic proportional relief valve 62 that controls the priority valve 59 is controlled, The pressure of the relief valve circuit 60b is proportionally controlled by an electric signal (current value) proportional to the articulate angle α, and the spool 59a of the priority valve 59 is shifted from the shift position shown in FIG. Proportional control is performed toward the shift position where priority is given to the flow rate supplied to.

  That is, when the articulate angle α is small, the shift amount of the spool 59a is also small, and the flow supplied from the pump 57 to the bucket working machine circuit 60a is prioritized, and the small turning pressure supplied to the small turning pressure supply circuit 60 is used. The inner ring brake pressure is controlled to be small in proportion to the articulate angle α.

  Further, when the articulate angle α is equal to or smaller than a threshold value (for example, 25 °), the larger the articulate angle α, the larger the shift amount of the spool 59a, and the flow rate supplied from the pump 57 to the bucket working machine circuit 60a. The inner wheel brake pressure for small turning supplied to the small turning pressure supply circuit 60 is controlled so as to increase in proportion to the articulate angle α.

  As a result, the small wheel inner wheel brake pressure proportional to the articulate angle α within the set pressure range set by the relief valve setting knob 70 is supplied to the left wheel brakes 37 and 38 corresponding to the inside of the turn of the articulated vehicle. The inner wheel brake torque proportional to the articulate angle α can be applied to the left rear axle 32 and the left front axle 35.

  On the other hand, when the articulate angle α exceeds a threshold value (for example, 25 °), the electromagnetic proportional relief valve 62 is controlled to an exciting force that can obtain a set pressure (for example, 5 MPa) set by the relief valve setting knob 70. Then, the inner wheel brake pressure for small turning supplied from the pump 57 to the small turning pressure supply circuit 60 is controlled to the maximum.

  At this time, the inner ring brake pressure (5.3 MPa) for small turning obtained by adding the biasing pressure (eg, 0.3 MPa) of the spring 59s to the set pressure (eg, 5 MPa) of the electromagnetic proportional relief valve 62 set by the relief valve setting knob 70. 5) is supplied to the left wheel brakes 37 and 38 corresponding to the inside of the left turn of the articulated vehicle as shown in FIG. 5, and the maximum brake torque can be applied to the left rear axle 32 and the left front axle 35.

(Step 12)
In the case of clockwise rotation, the next clockwise small turning brake mode is activated.

  That is, the power supply of the solenoid A of the small left turn control valve 63 is controlled to be turned off, and the small left turn control valve 63 is controlled to the spring return position, that is, the valve closed position. The small right turn control valve 64 is controlled to the switching position, that is, the valve open position, and the solenoids a and b of the solenoid valves 56A and 56B are turned on to control the solenoid valve 56A. , 56B are controlled to the switching position, that is, the valve closing position. By these controls, the circuit between the left brake circuit 41 and the right brake circuit 42 is cut off, the hydraulic oil supply from the small turning pressure supply circuit 60 to the left wheel brakes 37 and 38 is cut off, and the small turning pressure supply circuit The hydraulic oil can be supplied from 60 to the right wheel brakes 39 and 40.

  At the same time, when the articulate angle α detected by the articulate angle sensor 72 is not more than a threshold value (for example, 25 °), the power supply of the solenoid E of the electromagnetic proportional relief valve 62 that controls the priority valve 59 is controlled, The pressure of the relief valve circuit 60b is proportionally controlled by an electric signal (current value) proportional to the articulate angle α, and the spool 59a of the priority valve 59 is shifted from the shift position shown in FIG. Proportional control is performed toward the shift position where priority is given to the flow rate supplied to.

  That is, as in the case of step 11, when the articulate angle α is small, the shift amount of the spool 59a is also small, and the flow supplied from the pump 57 to the bucket working machine circuit 60a is prioritized, and the small turning pressure supply circuit The inner wheel brake pressure for small turning supplied to 60 is controlled to be small, but as the articulate angle α increases, the shift amount of the spool 59a also increases, and the inner wheel brake for small turning supplied to the small turning pressure supply circuit 60 The pressure is controlled to increase in proportion to the articulate angle α.

  As a result, the small wheel inner wheel brake pressure proportional to the articulate angle α within the set pressure range set by the relief valve setting knob 70 is supplied to the right wheel brakes 39 and 40 corresponding to the inside of the turn of the articulated vehicle. Thus, the inner wheel brake torque proportional to the articulate angle α can be applied to the right rear axle 33 and the right front axle 36.

  On the other hand, when the articulate angle α exceeds a threshold value (for example, 25 °), the electromagnetic proportional relief valve 62 is controlled to an exciting force with which a constant relief pressure (for example, 5 MPa) is obtained, The inner wheel brake pressure for small turning supplied to the pressure supply circuit 60 is controlled to the maximum.

  At this time, the inner ring brake pressure (5.3 MPa) for small turning obtained by adding the biasing pressure (eg, 0.3 MPa) of the spring 59s to the set pressure (eg, 5 MPa) of the electromagnetic proportional relief valve 62 set by the relief valve setting knob 70. ) To the right wheel brakes 39 and 40 corresponding to the inside of the right turn of the articulated vehicle, and the maximum brake torque can be applied to the right rear axle 33 and the right front axle 36.

  Next, functions and effects of the embodiment shown in FIGS. 1 to 5 will be described.

  If the operator does not wish to activate the small turning brake mode, the operator keeps the small turning switch 69 off. The controller 74 controls the solenoid valves 56A and 56B to be in an open state by turning off the solenoids a and b of the solenoid valves 56A and 56B in the normal brake mode shown in FIG. By turning off the solenoids A and B of the small turning control valve 64 and controlling the left small turning control valve 63 and the right small turning control valve 64 to the closed state, the left wheel brakes 37 and 38 and the right Brake hydraulic fluid can be supplied to all wheel brakes 39 and 40 at the same time.

  The operator turns on the small turning switch 69 when he wants to activate the small turning brake mode. When the steering handle 22H of the vehicle is turned with the small turning switch 69 turned on, the controller 74 controls the solenoid E of the electromagnetic proportional relief valve 62 in the small turning brake mode shown in FIG. The shift position of the spool 59a of the priority valve 59 is controlled, the flow rate supplied from the pump 57 to the small turning pressure supply circuit 60 is controlled by the shift position of the spool 59a, and the small amount from the pump 57 to the small turning pressure supply circuit 60 is controlled. The inner wheel brake pressure for turning is controlled in proportion to the articulate angle α detected by the articulate angle sensor 72, and the turning direction (counterclockwise or clockwise) is judged by the articulate angle α, and the articulate angle sensor A small swing brake module that controls one of the left and right small swing control valves 63 and 64 corresponding to the inside of the swing direction detected at 72 to open. To start the de.

  Then, by operating one of the left wheel brakes 37, 38 or the right wheel brakes 39, 40, a turning radius determined by an articulation angle α that causes the rear vehicle body 21 and the front vehicle body 23 to bend each other through the articulate shaft 22 is obtained. It is possible to further reduce the size.

  At this time, the brake pressure of the left wheel brakes 37, 38 or the right wheel brakes 39, 40 located on the turning inner wheel side, that is, the turning inner wheel side brake pressure, is articulated within the set pressure range set by the relief valve setting knob 70. The brake pressure can be adjusted arbitrarily in proportion to the angle α. The smaller the articulate angle α, the smaller the inner brake pressure on the turning inner wheel side, and the larger the articulate angle α, the more on the turning inner wheel side. The brake pressure increases in proportion to the articulate angle α within the limit of the set pressure, and as the brake pressure increases, the force to reduce the turning radius works, so the smooth turning behavior according to the turning handle operation amount Become.

  Even during the small turning brake operation, the priority valve 59 supplies the flow rate from the pump 57 to the small turning pressure supply circuit 60 and at the same time distributes the flow rate to the bucket working machine circuit 60a. Since the bucket working machine 26 can be operated after being supplied, bucket work such as scooping earth and sand with the bucket 26b can be performed while making a small turn.

  When the steering handle 22H is returned to the straight traveling direction, the controller 74 operates the normal brake mode to control the relief pressure of the electromagnetic proportional relief valve 62 to 0 MPa, so that the spool 59a of the priority valve 59 is shown in FIG. A pilot operation is performed at the indicated position, and the inside of the small turning pressure supply circuit 60 is depressurized to a predetermined residual pressure.

  Even if the small turning switch 69 is turned on and the steering handle 22H is turned, a small turning at a high speed is not preferable. Therefore, the vehicle speed V detected using the vehicle speed sensor 71 is a vehicle speed threshold, for example, When the vehicle speed exceeds 10 km / h, the normal brake mode is activated in the same manner as when the steering handle 22H is returned.

  Even if the small turning switch 69 is turned on and the steering handle 22H is turned, running on the ice burner is not preferable because the side slip of the tire is not preferable. When the side slip angle β exceeds a side slip angle threshold value, for example, 30 °, the normal brake mode is activated as in the case of returning the steering handle 22H.

  As described above, in the small turning control device that makes a small turn by operating the left and right wheel brakes 37, 38 or 39, 40 of the articulated vehicle, the priority valve 59 separates the brake master cylinder 51 from the priority valve 59. The flow rate to the small turning pressure supply circuit 60 that supplies hydraulic oil discharged from the installed pump 57 to one of the left wheel brakes 37 and 38 and the right wheel brakes 39 and 40, and the flow rate to the bucket work machine circuit 60a In order to give priority to the flow rate to one of them, pilot control is performed so that the priority flow rate of the priority valve 59 is given priority to the bucket work machine circuit 60a when the relief pressure is unloaded by the electromagnetic proportional relief valve 62. At the same time, the priority valve 59 is connected to the small turning pressure supply circuit 60 by changing the relief pressure to an adjusted value by an electric signal. The pilot control is performed so as to give priority to the amount, and the pressure of the small turning pressure supply circuit 60 is controlled based on the relief pressure, and the pressure controlled by the electromagnetic proportional relief valve 62 is controlled by the left small turning control valve 63. Since the brake pressure is supplied to the left wheel brakes 37 and 38 and the right small turning control valve 64 supplies the pressure controlled by the electromagnetic proportional relief valve 62 to the right wheel brakes 39 and 40 as the brake pressure, the bucket An inexpensive inner ring brake pressure supply circuit for small turning can be configured by using the existing pump 57 used in the work machine circuit 60a.

  Using this small turning inner wheel brake pressure supply circuit, the small turning switch 69 for selecting the small turning brake mode for supplying the hydraulic oil to only one of the left wheel brakes 37 and 38 and the right wheel brakes 39 and 40 is turned on. Then, when there is a steering wheel turning operation that refracts the front vehicle body 23 with respect to the rear vehicle body 21, the controller 74 shifts the priority valve 59 via the electromagnetic proportional relief valve 62 to transfer from the pump 57 to the small turning pressure supply circuit 60. Priority is given to the supplied flow rate, and the inner ring brake pressure for small turning from the pump 57 to the small turning pressure supply circuit 60 is controlled in proportion to the articulate angle α, and the turning direction detected by the articulate angle sensor 72 is controlled. Since either the left small turning control valve 63 or the right small turning control valve 64 corresponding to the inside is controlled to be in the valve open state, the front vehicle body 23 is attached to the rear vehicle body 21. Even if the fully articulated state is not refracted as much as possible, the small turning brake mode can be activated, eliminating the need for many steering wheel turning operations by the vehicle operator and enabling small turning of the vehicle with few turning operations. Can be reduced.

  At that time, the controller 74 controls the relief pressure of the electromagnetic proportional relief valve 62 in proportion to the articulate angle α within the range from the no-load state to the set pressure, and shifts the spool 59a of the priority valve 59, The inner wheel brake pressure for small turning supplied from the pump 57 to the small turning pressure supply circuit 60 is controlled in proportion to the articulate angle α detected by the articulate angle sensor 72, and the left wheel brakes 37, 38 on the turning inner wheel side are controlled. Or, since the right wheel brakes 39 and 40 are supplied, the appropriate small turning inner wheel brake torque controlled according to the vehicle body refraction angle of the front vehicle body 23 with respect to the rear vehicle body 21 (that is, proportional to the articulate angle α), Smooth turning behavior can be obtained, and good ride comfort can be obtained.

  In addition, a low-priced inner ring brake pressure supply circuit for small turning that effectively uses the existing pump 57 used in the implement system for operating the bucket working machine 26 is configured, and when a small turning is necessary, an electromagnetic proportional relief is provided. The valve 62 shifts the spool 59a of the priority valve 59 to a position where priority is given to the flow rate from the pump 57 to the bucket working machine circuit 60a to the small turning pressure supply circuit 60, and the left wheel brakes 37, 38 and the right wheel Since the required small-turn inner-wheel brake pressure for one of the brakes 39 and 40 is obtained, energy saving and low cost can be achieved as compared with the case where a dedicated brake pump is employed.

  In addition, when there is at least one of a handle returning operation for returning the front vehicle body 23 to the straight direction with respect to the rear vehicle body 21 and a normal brake operation, the priority valve 59 is returned via the electromagnetic proportional relief valve 62 under the control of step 2. As a result, priority is given to the flow rate supplied from the pump 57 to the bucket working machine circuit 60a, and the relief pressure of the electromagnetic proportional relief valve 62 is controlled to the no-load state (0 MPa). It is possible to release the pressure, release the small turning brake mode, and use all the brakes of the left wheel brakes 37 and 38 and the right wheel brakes 39 and 40 by the hydraulic oil supplied from the brake master cylinder 51. Since the normal brake mode is activated, the normal brake mode is prioritized over the small turning brake mode to High reliability can be secured.

  The controller 74 determines that the vehicle speed V of the articulated vehicle detected by the vehicle speed sensor 71 is lower than the vehicle speed threshold value, and the side slip angle β of the articulated vehicle calculated from the data from the yaw angular velocity sensor 73 is the side slip angle threshold value. If it is lower, it can be controlled to the small turning brake mode, but the small turning brake mode is canceled when the vehicle speed V exceeds the vehicle speed threshold and when the side slip angle β exceeds the side slip angle threshold. In addition, the brake master cylinder 51 activates the normal brake mode in which all-wheel braking can be applied, so that the small turning brake control is automatically disabled when the vehicle body is unstable and the vehicle body is Stability can be secured.

  Further, separately from the brake master cylinder 51, the flow rate to the small turning pressure supply circuit 60 that supplies the hydraulic oil discharged from the pump 57 to one of the left wheel brakes 37, 38 and the right wheel brakes 39, 40, and the bucket working machine Use the priority valve 59 that prioritizes the flow to either one of the flow to the circuit 60a, and supply the flow from the pump 57 to the small swivel pressure supply circuit 60 without switching the flow completely. Even during the operation, the bucket work machine 26 can be operated by supplying a flow rate from the pump 57 to the bucket work machine circuit 60a at the same time, and the bucket work while making a small turn, for example, earth and sand The work which asks for etc. becomes possible.

  The present invention is used in the manufacturing industry of articulated vehicles such as wheel loaders.

21 Rear body
22 Articulate shaft
23 Front car body
26 Bucket work machine
37, 38 Left wheel brake
39, 40 Right wheel brake
51 Brake master cylinder
57 Pump
59 priority valve
60 Small turning pressure supply circuit
60a Bucket work machine circuit as other circuit
62 Proportional relief valve
63 Small left turn control valve
64 Right small turning control valve
69 Small swivel switch
71 Vehicle speed sensor
72 Articulate angle sensor
73 Yaw angular velocity sensor
74 Controller

Claims (4)

In an articulated vehicle in which a rear vehicle body and a front vehicle body are connected to each other through an articulate shaft so as to be able to be bent,
An articulated angle sensor that detects the articulated angle and the direction of refraction of the front vehicle body that is refracted relative to the rear vehicle body;
A brake master cylinder for supplying brake pressure to both the left wheel brake for braking the left wheel and the right wheel brake for braking the right wheel;
A small turning pressure supply circuit for supplying the working fluid discharged from the pump separately from the brake master cylinder to one of the left wheel brake and the right wheel brake;
Other circuits using the above-mentioned pump in common with the small swirl pressure supply circuit as a working fluid pressure source
A priority valve that prioritizes the flow rate to one of the flow rate to the small swirl pressure supply circuit and the flow rate to the other circuit;
By controlling the relief pressure to a no-load state, the priority valve is pilot controlled to a shift position that prioritizes the flow rate to other circuits, and the priority valve is controlled to increase the relief pressure by an electric signal, thereby reducing the priority valve to a small turning pressure. An electromagnetic proportional relief valve that pilot controls the shift position to increase the flow rate to the supply circuit and controls the pressure of the small turning pressure supply circuit according to the relief pressure;
A small left turn control valve that supplies the pressure controlled by the electromagnetic proportional relief valve to the left wheel brake as a brake pressure;
A small right turn control valve that supplies pressure controlled by the electromagnetic proportional relief valve to the right wheel brake as a brake pressure;
A small turning switch for selecting a small turning brake mode for supplying a working fluid to only one of the left wheel brake and the right wheel brake;
If there is a steering wheel turning operation that refracts the front car body relative to the rear car body with the small swivel switch on, the relief pressure of the electromagnetic proportional relief valve is controlled according to the articulate angle within the range from the no-load state to the set pressure. Then, by shifting the priority valve, the inner ring brake pressure for small turning supplied from the pump to the small turning pressure supply circuit is controlled according to the articulate angle detected by the articulate angle sensor, and the articulate angle sensor A controller having a function of activating a small turning brake mode for controlling one of the left small turning control valve and the right small turning control valve corresponding to the inside of the detected turning direction to a valve open state. A small turning control device for an articulated vehicle. The controller
When there is at least one of a handle return operation for returning the front vehicle body to the rear vehicle body in a straight direction and a normal brake operation for supplying working fluid from the brake master cylinder to the left wheel brake and the right wheel brake during the small turn. In addition to canceling the small turning brake mode, it has a function to operate the normal brake mode that enables the left wheel brake and the right wheel brake to be used by the working fluid supplied from the brake master cylinder. The small turning control device for an articulated vehicle according to claim 1. A vehicle speed sensor for detecting the vehicle speed of the articulated vehicle;
A yaw angular velocity sensor for calculating the side slip angle of the articulated vehicle,
The controller
When the vehicle speed exceeds the vehicle speed threshold and when the side slip angle exceeds the side slip angle threshold, the small turning brake mode is canceled and the left wheel brake and right side are driven by the working fluid supplied from the brake master cylinder. The small turning control device for an articulated vehicle according to claim 1 or 2, further comprising a function of operating a normal brake mode in which all wheel brakes of the wheel brake can be applied. The other circuit is a bucket work machine circuit that operates a bucket work machine mounted on the front vehicle body. 4. The small turning control device for an articulated vehicle according to any one of claims 1 to 3.

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