JP3467194B2 - Travel control device - Google Patents

Description

BACKGROUND OF THE INVENTION [0001] [Technical Field of the Invention The present invention relates to the running system GoSo location having a closed circuit and closed circuit for the right travel for left travel. 2. Description of the Related Art For example, when a hydrostatic power transmission system (hereinafter referred to as "HST system") is used in a vehicle requiring a large traction force such as a bulldozer, a large-capacity hydraulic motor is used. Alternatively, it is necessary to use a plurality of hydraulic motors. When a large-capacity hydraulic motor or a plurality of hydraulic motors are used, a large-capacity hydraulic pump or a plurality of hydraulic pumps are required at the same time. In the case of a system using a plurality of hydraulic pumps and a plurality of hydraulic motors, as shown in JP-A-10-122363, for example, a left and right traveling drive system such as a bulldozer is provided as one set for left traveling. Independently configured by a hydraulic circuit for left running in which a hydraulic pump and a hydraulic motor are connected in a closed circuit, and a hydraulic circuit for right running in which a pair of hydraulic pumps and a hydraulic motor for right running are connected in a closed circuit. The method of doing is taken. [0005] As described above, when the left and right traveling drive systems are independent hydraulic circuits, H
Due to manufacturing tolerances of the hydraulic pump of the ST system, the discharge flow rates discharged from the left and right hydraulic pumps are different even during straight running, which may cause a difference in the number of rotations between the motor shafts of the left and right hydraulic motors. . In such a case, a difference occurs in the rotational speeds of the left and right crawler belt sprockets driven by the left and right motor shafts, making it difficult to maintain straightness. [0006] The present invention has been made in view of such a point, and an object of the present invention is to secure stable straightness. SUMMARY OF THE INVENTION The present invention is directed to a vehicle for driving left.
For forward and backward to the strange displacement pump and traction motor
The closed circuit for left running and the right
The variable displacement pump for traveling and the traveling motor are
And right-hand drive closed by the main line for reverse
Circuit and closed circuits for left and right running when driving straight ahead
Short circuit the main lines for forward
Forward short-circuit valve that releases the short-circuit during turning operation
When the vehicle is going straight, the closed circuits for left and right
Short circuit between main lines for reverse
A reverse short-circuit valve that releases the short-circuit
Short-circuit valve for forward and short-circuit valve for reverse during reverse operation
Control and release those short circuits during turning operation
Controller and a short-circuit valve for advance
If the pressure between the forward main lines in the closed circuits for left and right running is equal in a short-circuited state by the forward short-circuit valve, the short circuit between the main lines is maintained and the difference between the main lines is maintained. A short-circuit release valve for releasing the short circuit when pressure is generated and a short-circuit valve for reverse movement in series
Provided, between the main line with maintains a short circuit between the main line when equal pressure between the main line for reverse in closed circuit for the left traveling and right traveling under short-circuit conditions due to the short circuit valve for reverse And a reverse release valve for reverse which releases a short circuit when a differential pressure occurs. [0008] Thus, when the vehicle is in a forward straight-ahead operation, the control
Switch the short circuit valve for advance by the signal from the roller,
A main circuit for traveling with a closed circuit for running and a closed circuit for right running
In addition to shorting the lines,
Switching the reverse short-circuit valve by the signal from the controller
By shorting the main lines for reverse,
From each variable displacement pump for traveling to it for left and right traveling
Keep the hydraulic oil flow supplied to each traction motor equal.
That is, a stable straightness is ensured. Also, during turning operation
Releases the short-circuit valve, and the closed circuit for left running and right running
Independent of the closed circuit for Furthermore, when different loads are applied to the left and right traveling motors while the left and right closed circuits are short-circuited by the forward and reverse short-circuit valves, the motor shaft rotation speed on the high load side decreases and straightness is maintained. Lost
At this time, a differential pressure is generated between the left and right main lines, and the forward and reverse short-circuit release valves operate, so the left and right closed circuits are released as independent circuits, and the straightness is greatly deteriorated. Is prevented. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to an embodiment shown in FIG. FIG. 1 shows a hydrostatic system for a traveling system.
This is a travel control device used for construction machines such as bulldozers having a power transmission, and a closed circuit 11 for left travel and a closed circuit 12 for right travel are provided independently. The closed circuit 11 for left running includes a variable displacement pump 14 for left running incorporated in the pump unit 13 for left running.
And a traveling motor 15 for driving a crawler belt for left traveling, on the pump forward traveling discharge side (hereinafter simply referred to as “forward”).
And the main line 17 of the pump on the discharge side for reverse travel (hereinafter simply referred to as “reverse travel”). On the other hand, the right running closed circuit 12 includes a right running variable displacement pump 22 incorporated in a right running pump unit 21 and a running motor 23 for driving a right running crawler. The main line 24 for forward movement and the main line 25 for reverse movement communicate with each other. The variable displacement pump 14 for traveling left and the variable displacement pump 22 for traveling right are driven by a common engine 26. The left and right running variable displacement pumps 14 and 22 have swash plates 27 and 28 for controlling the direction and amount of discharge of hydraulic oil, respectively, and the swash plates 27 and 28 are tilted. By controlling the direction and the tilt angle by the respective swash plate control cylinders 29 and 30, the hydraulic oil discharge direction and the discharge amount are controlled respectively. Each swash plate control cylinder 29, 30 is controlled by a proportional solenoid valve 31, 32, 33, 34. These electromagnetic proportional valves 31, 32, 33, 34 are provided with springs 31a, 32a, 33a, 34a at one end of the spool, and solenoids 31b, 32b, 33b, 34b at the other end of the spool. Have been. The solenoid 31 of the proportional solenoid valves 31, 32, 33, 34
In b, 32b, 33b, and 34b, electric signals calculated by the controller 36 from the operation direction and operation amount of the electric joystick 35 manually operated by an operator such as a bulldozer are signal lines a, b, c, and d. Is entered through
The electromagnetic proportional valves 31, 32, 33, 34 control the hydraulic oil supplied to the swash plate control cylinders 29, 30 according to these input signals. That is, the outlets of the left-reverse electromagnetic proportional valve 31 and the left-forward electromagnetic proportional valve 33 are respectively connected to the left-traveling swash plate control cylinder 29, and the right-reverse electromagnetic proportional valve 32 is provided.
The outlet of the electromagnetic proportional valve 34 for rightward advance is connected to the swash plate control cylinder 30 for rightward travel, respectively. The drive shaft 41 of the engine 26 that drives the left and right traveling variable displacement pumps 14 and 22 supplies hydraulic fluid to the left traveling closed circuit 11 and the right traveling closed circuit 12. Charge pumps 42 and 43 for replenishing are provided, respectively.
The discharge side is connected to a relief valve 45 for setting a charge pressure and a relief make-up valve 46. The relief make-up valve 46 is a crossover formed by combining a pair of relief valves and a check valve. The relief make-up valve 46 allows the hydraulic oil to escape from the high pressure side to the low pressure side and is discharged from the charge pumps 42 and 43. It has the function of replenishing the working oil to the low pressure side. In the discharge line of the charge pump 42 for left running, the pilot primary pressure supplied to the electromagnetic proportional valves 31 to 34 via the primary pressure line 47P is maintained at a pressure level corresponding to the engine speed. Are provided. The oil drain lines 47T of the electromagnetic proportional valves 31 to 34 are communicated with the tank 44. On the other hand, the left traveling pump unit 13 and the right traveling pump unit 21 apply an excessive pressure increase generated in the closed circuits 11 and 12 for the left traveling and the right traveling to the shuttle valve.
49, and by lowering the pilot primary pressure supplied to the electromagnetic proportional valves 31 to 34, the variable displacement pumps 14, 22
A pressure control valve 50 for controlling the swash plate control cylinders 29, 30 in the neutral position direction is provided. A traveling motor 1 for left traveling and right traveling
5 and 23 are variable displacement pumps 1 for left and right running
The left and right crawler belt driving sprockets such as bulldozers are operated at the number of rotations according to the hydraulic oil flow supplied from 4, 22. A closed circuit 1 for left and right running.
The forward main lines 16 and 24 in 1 and 12 can be short-circuited by a forward short circuit line 51 provided between the main lines 16 and 24, while the left and right traveling closed lines are closed. Reverse main line in circuits 11 and 12
17 and 25 can be short-circuited by a reverse short-circuit line 52 provided between the main lines 17 and 25. Further, in the forward short-circuit line 51, a forward short-circuit valve 53 and a forward short-circuit release valve 54 are provided in series, while in the reverse short circuit line 52, a reverse A short-circuit valve 55 for reverse use and a short-circuit release valve 56 for reverse use are provided in series. Short circuit valve 53 for forward movement and short circuit valve 55 for reverse movement
Is a normally open valve having a spring 57 at one end of the spool for urging the spool to the short-circuit release position, and a solenoid 58 at the other end of the spool to switch the spool to the short-circuit position by energization. Short circuit valve
Signal lines e and f from the controller 36 are connected to the solenoids 58 in 53 and 55, and the signal line e from the controller 36 only when the electric joystick 35 is operated straight forward or backward by an operator such as a bulldozer. , F, through the electric signal output from the solenoid
58 is excited, and the short-circuit valves 53 and 55 are switched to the short-circuit position. The forward short-circuit valve 53 connects the forward main lines 16 and 24 in the left running and right running closed circuits 11 and 12 to each other at the short-circuit position by the excitation of the solenoid 58 during forward straight operation. In addition to the short-circuit, the power supply to the solenoid 58 is stopped during the forward turning operation, so that the short-circuit line 51 is switched to the position where the short-circuit line 51 is cut off by the spring 57 to release the short-circuit. Similarly, the reverse short-circuit valve 55 short-circuits the reverse main lines 17, 25 in the closed circuits 11, 12 for left traveling and right traveling during the reverse straight traveling operation, and also performs the reverse turning traveling operation. Release the short circuit. Further, the short-circuit release valve 54 for forward movement and the short-circuit release valve 56 for reverse movement have a neutral position where the short-circuit lines 51 and 52 are communicated by springs 61 provided at both ends of the spool. When a pressure difference is generated between the short-circuit lines on both sides via the short-circuit release valves 54 and 56, a switching position is provided in which the short-circuit lines 51 and 52 are cut off by introducing the pressure difference to both ends of the spool via the pilot line 62. The forward short-circuit release valve 54 short-circuits the forward short-circuit valve 53 so that the pressure between the forward main lines 16 and 24 in the left running and right running closed circuits 11 and 12 is reduced. When they are equal, the short circuit between the main lines 16 and 24 is maintained at the neutral position, and when a differential pressure is generated between the main lines 16 and 24, the differential pressure is
Therefore, even if the forward short-circuit valve 53 is in a short-circuit state, the forward short-circuit release valve 54
Operates in the switching position to release the short circuit. Similarly, the reverse short-circuit release valve 56 is connected to the pressure between the reverse main lines 17 and 25 in the closed circuits 11 and 12 for left and right running in a short-circuit state by the short-circuit valve 55 for reverse. Are equal to each other, a short circuit between the main lines 17 and 25 is maintained at the neutral position, and when a differential pressure is generated between the main lines 17 and 25, even if the short circuit valve 55 for reverse travel is in a short circuit state, Then, the reverse short-circuit release valve 56 is operated to the switching position by the differential pressure to release the short-circuit. Next, the operation of the illustrated embodiment will be described. When the operator operates the electric joystick 35, the electric signal calculated by the controller 36 is applied to the solenoids 31b, 32b, 32b, 32b, 32b of the electromagnetic proportional valves 31, 32, 33, 34.
Hydraulic oil output to the swash plate control cylinders 29 and 30 of the two variable displacement pumps 14 and 22 and output to the variable displacement pumps 14 and 22
The discharge direction and discharge flow rate of the hydraulic oil supplied to the left and right traveling motors 15 and 23 are controlled, and the forward or backward movement, left or right turn, and traveling speed of the vehicle are controlled. For example, when performing a straight forward operation, the controller 36 controls the solenoids 33b,
An excitation signal equal to 34b is output, and the variable displacement pump 1
At the same time that the swash plate control cylinders 29 and 30 of the cylinders 4 and 22 operate equally on the forward side, an excitation signal is supplied from the controller 36 to the solenoid 58 of the short circuit valve 53 for advance, and the short circuit valve 53 is short-circuited against the spring 57. The main lines 16, 24 for forward movement in the left and right closed circuits 11, 12 are short-circuited by the short-circuit valve 53 and the normally-open short-circuit release valve 54. Similarly, when performing the straight-ahead operation of the reverse travel, the controller 36 controls the solenoids 31b,
An excitation signal equal to 32b is output, and the variable displacement pump 1
At the same time that the swash plate control cylinders 29 and 30 of the motors 4 and 22 operate equally to the reverse side, the excitation signal is supplied from the controller 36 to the solenoid 58 of the short circuit valve 55 for the reverse movement, and the short circuit valve 55 is short-circuited against the spring 57 The main lines 17 and 25 for reverse movement in the left and right closed circuits 11 and 12 are short-circuited by the short-circuit valve 55 and the normally-open short-circuit release valve 56. In any case, the closed circuit 11 for left running and the closed circuit 12 for right running are no longer completely independent circuits,
Even if there are manufacturing tolerances in the variable displacement pumps 14 and 22 for left and right running, the flow rate of hydraulic oil supplied to the left and right running motors 15 and 23 can be kept equal, and good straightness can be maintained. It is. [0034] In addition, during the forward straight operation, the short-circuit valve for forward movement is provided.
Because only 53 is excited to short-circuit the main lines 16 and 24 for forward movement, and during straight-ahead operation for reverse, only the short-circuit valve 55 for reverse is excited to short-circuit the main lines 17 and 25 for reverse movement.
By minimizing the short-circuit location, the energy required for the short-circuit can be saved. For example, the energy can be saved more than when the two short-circuit valves 53 and 55 are excited at the same time. On the other hand, when a left turning operation or a right turning operation is performed by the electric joystick 35, the controller 36 which senses the turning operation operates the short circuit valve 53 for forward movement or the short circuit valve 55 for reverse movement. Since the excitation signal to each solenoid 58 is canceled, the forward short-circuit valve 53 or the reverse short-circuit valve 55 is returned to the short-circuit release position by the spring 57, and the left traveling closed circuit 11 and the right traveling Closed circuit 12
The short circuit between the main lines 16 and 24 for forward movement or between the main lines 17 and 25 for reverse movement in the above is released to make the two closed circuits 11 and 12 independent. This allows the vehicle to make a left turn or a right turn, depending on the flow rate of the hydraulic oil supplied to the left and right running motors 15, 23. Further, during the straight-ahead operation, since the left and right closed circuits 11, 12 are short-circuited by the forward and backward short-circuit valves 53, 55, when the vehicle crosses an inclined ground diagonally, etc.
When there is a difference between the left and right driving torques, that is, when different loads are applied to the left and right traveling motors 15 and 23, the rotation speed of the motor shaft on the high load side decreases, and it becomes impossible to maintain straightness. At this time, a differential pressure is generated between the forward main lines 16 and 24 and the reverse main lines 17 and 25, and the differential pressure causes the forward short-circuit release valve 54 and the reverse short-circuit release valve 56 to reach the neutral position. , The short circuit lines 51 and 52 are cut off, and the left and right closed circuits 11 and 12 become independent circuits in which the short circuit is released, thereby preventing a significant deterioration in straightness. According to the present invention, at the time of a straight forward operation of forward movement,
Switching the short-circuit valve for advance by the signal from the controller
And a closed circuit for left running and a closed circuit for right running
Short-circuit the main lines and move straight backward
At times, a short-circuit valve for reverse is
Switch and short-circuit the main lines for reverse
With the variable displacement pumps for left and right running
The flow rate of hydraulic oil supplied to each traveling motor
It is possible to maintain the same straightness and to maintain stable straightness,
Operator satisfaction can be improved, and pumps and
Fine adjustment work of motor and motor can be shortened. In addition, turning operation
At the time of operation, the short-circuit valve is released and the closed circuit for left traveling and the right
Independent of the closed circuit for traveling, each hydraulic oil flow
Can secure turning travel. Furthermore, when different loads are applied to the left and right traveling motors while the left and right closed circuits are short-circuited by the forward and backward short-circuit valves , the forward and reverse travel is performed by the differential pressure generated between the left and right main lines. Since the short-circuit release valve operates, the left and right closed circuits become independent circuits with the short-circuit released, and it is possible to prevent a significant deterioration in straightness in a short-circuit state.

Is an electrical and hydraulic circuit diagram showing an embodiment of according to the running system GoSo location BRIEF DESCRIPTION OF THE DRAWINGS [Figure 1] Inventive. [Description of Signs] 11, 12 Closed circuit 14, 22 Variable displacement pump 15, 23 Traveling motor 16, 17, 24, 25 Main line 36 Controller 53, 55 Short circuit valve 54, 56 Short circuit release valve

Claims (1)

(57) [Claims] [Claim 1] A variable displacement pump for left traveling and a traveling motor
Communication with the main line for forward and reverse
The closed circuit for left running, the variable displacement pump for right running and the running motor
And for the right-hand drive connected by the main line for reverse
In the closed circuit, and in the closed circuit for left traveling and right traveling during straight ahead operation
Short circuit the main lines for forward movement and turn
In the forward short circuit valve that releases the short circuit during operation, and in the closed circuit for left traveling and right traveling during straight operation
Short circuit the main lines for reverse and turn
Short-circuit valve for reverse to release the short-circuit during operation, short-circuit valve for forward and short-circuit for reverse during straight-ahead operation
And short-circuit control during turning operation.
A controller dividing provided short valve series with the forward, when the pressure between the main line for forward in closed circuit for the left traveling and right traveling under short-circuit conditions due to the short circuit valve for forward equals its main a short release valve for forward to release the short circuit when the differential pressure is generated between the main line while maintaining a short circuit between lines, provided short valve in series for reverse, short circuit due to a short circuit valve for reverse In this state, if the pressure between the main lines for reverse running in the closed circuits for left and right running is equal, the short circuit between the main lines is maintained, and if a pressure difference occurs between the main lines, the short circuit is released. run line controller you characterized by comprising a short release valve for reverse to.