JPH0245076Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a traveling hydraulic motor circuit for a hydraulically driven vehicle driven by a traveling hydraulic motor.

[Background of the idea]

Hydraulically driven vehicles used as civil engineering and construction machinery are generally heavy and require a large amount of inertia energy while running. 2. Description of the Related Art A traveling hydraulic motor circuit is known that includes a brake valve that absorbs inertial energy of a running vehicle and brakes a traveling hydraulic motor.

FIG. 1 is a circuit diagram showing an example of such a conventional hydraulic motor circuit for traveling, in which 1 indicates an engine, 2
is a hydraulic pump driven by the engine 1; 3 is a travel hydraulic motor driven by hydraulic pressure from the hydraulic pump 2; and 4 is supplied from the hydraulic pump 2 to the travel hydraulic motor 3. A directional control valve for controlling pressure oil, 5 is a main relief valve. 6 is a brake valve, and a circuit consisting of a relief valve 7 and a check valve 8 and a circuit consisting of a relief valve 9 and a check valve 10 are connected to two outlet side pipes of the traveling hydraulic motor 3, respectively. It is placed in the crossover between 11 and 12. In the figure, 13 indicates an oil tank.

In the conventional traveling hydraulic motor circuit described above, when the directional switching valve 4 is switched, pressure oil from the hydraulic pump 2 is transferred to the traveling hydraulic motor 3 via the directional switching valve 4.
Return oil from the traveling hydraulic motor 3 is returned to the oil tank 13 via the directional control valve 4, and the traveling hydraulic motor 3 is driven. The traveling hydraulic motor 3 is driven at a rotational speed corresponding to the discharge amount of the hydraulic pump 2, that is, the rotational speed of the engine 1.
The operator can move the vehicle forward or backward at any speed by operating the accelerator in the driver's seat. When the operator takes his foot off the accelerator to operate the brakes while driving, the rotational speed of the engine 1 decreases, the discharge amount of the hydraulic pump 2 decreases, and the inertial energy of the vehicle is transferred to the hydraulic oil by the brake valve 6. is converted into thermal energy and absorbed, the rotational speed of the traveling hydraulic motor 3 decreases, and the vehicle decelerates. Next, a brake device (not shown) is provided independently of this hydraulic motor circuit for traveling.
By operating the , a running vehicle can be decelerated to a desired speed.

In this manner, in the conventional travel hydraulic motor circuit, the inertial energy of the vehicle is absorbed by the brake valve 6, thereby assisting the braking by the brake device arranged independently of the travel hydraulic motor circuit. It's becoming like that. However, the braking effect by the brake valve 6 cannot be increased too much from the viewpoint of ride comfort of the vehicle and temperature control of the hydraulic oil, and most of the inertial energy of the vehicle is generated by the hydraulic motor circuit for driving. Braking must be performed by an independently provided brake device. Under these circumstances, hydraulically driven vehicles with large inertial energy must be equipped with a large-capacity brake device in order to exhibit the required braking performance, resulting in various disadvantages in vehicle design.

In order to solve the above problems, a circuit (meter-out circuit) has been proposed in which a throttle valve is inserted in the outlet side conduit of the travel motor to adjust the rotation speed of the travel motor (meter-out circuit). Since this type of circuit includes a fixed throttle valve with a fixed throttle amount as a throttle valve, it has the disadvantage that the circuit efficiency of the traveling hydraulic motor circuit is reduced, and is not preferred in practice.

[Purpose of invention]

The present invention was devised in view of the above circumstances, and it effectively absorbs the inertial energy of the vehicle without reducing the performance of the hydraulic motor for driving, reduces the load on the brake system, and improves the performance of the brake system. The object of the present invention is to provide a travel hydraulic motor circuit that can be downsized.

[Summary of the idea]

In order to achieve the above object, the present invention provides at least one of the two outlet side pipes of the traveling hydraulic motor driven by pressure oil from the hydraulic pump.
Set up a flow control means that can arbitrarily adjust the flow rate,
The present invention is characterized in that the throttling amount adjusting means of the flow rate controlling means is linked with a brake pedal for pressurized oil.

[Embodiment of the invention] Next, an embodiment of the invention will be described based on FIGS. 2 and 3.

FIG. 2 is a circuit diagram of a traveling hydraulic motor circuit according to the present invention, in which the same members as shown in FIG. 1 are denoted by the same reference numerals.

In this embodiment, a parallel circuit of a variable flow control valve 14 and a check valve 15 and a parallel circuit of a variable flow control valve 16 and a check valve 17 are connected to the two outlet pipes 11 and 12 of the travel hydraulic motor 3, respectively. A circuit is provided. The throttle amount adjusting means 14a, 16a of the variable flow rate control valves 14, 16 are connected to a brake pedal 18 disposed in the driver's seat, as shown in FIG. Correspondingly, the amount of restriction of the variable flow rate control valves 14, 16 is adjusted. Reference numeral 19 denotes a brake operating valve that controls the working fluid of a brake device (not shown), and has a push rod 19a connected to the brake pedal 18, and is configured to be switched in conjunction with the operation of the brake pedal 18. .

In the traveling hydraulic motor circuit of the above embodiment, when the directional control valve 4 is switched to the switching position F while the brake pedal 8 is not operated, the pressure oil of the hydraulic pump 2 is transferred to the directional control valve 4 and the check valve 15. , conduit 11
The return oil from the traveling hydraulic motor 3 is supplied to the traveling hydraulic motor 3 via the outlet pipe 12,
Since the oil is returned to the oil tank 13 via the variable flow rate control valve 16 and the direction switching valve 4, the traveling hydraulic motor 3 rotates in the normal direction, and the work vehicle moves forward. When the operator takes his foot off the accelerator to operate the brake,
The rotation speed of the engine 1 decreases and the discharge amount of the hydraulic pump 2 decreases, and the inertial energy of the vehicle is absorbed by the brake valve 6, and the rotation speed of the travel hydraulic motor 3 decreases and the vehicle decelerates. . Next, when the brake pedal 18 is operated, the brake operating valve 19 is switched and a brake device (not shown) is operated, and the amount of throttle of the variable control valve 16 increases in accordance with the amount of depression, and the travel hydraulic pressure is increased. As a result of the increase in the back pressure of the motor 3, the inertial movement of the wheels is suppressed, and the vehicle is decelerated and stopped.

Furthermore, when the directional control valve 4 is switched to the switching position R while the brake pedal 18 is not operated, the pressure oil of the hydraulic pump 2 is transferred through the directional control valve 4, the check valve 17, and the pipe line 12. The return oil from the traveling hydraulic motor 3 is supplied to the traveling hydraulic motor 3 through an outlet pipe 11, a variable flow rate control valve 14,
Since the oil returns to the oil tank 13 via the directional control valve 4, the traveling hydraulic motor 3 is reversed, and the vehicle moves backward. Next, when the brake pedal 18 is operated,
The brake operating valve 19 switches and a brake device (not shown) operates, and the amount of throttle of the variable flow control valve 6 increases in accordance with the amount of depression, resulting in an increase in the back pressure of the travel hydraulic motor 3. , the inertial motion of the wheels is suppressed, and the vehicle is decelerated and stopped.

The travel hydraulic motor circuit of the above embodiment increases the back pressure of the travel hydraulic motor 3 in accordance with the brake operation in both forward and reverse travel,
Inertial motion of the vehicle can be suppressed.

The above embodiment is an example in which variable flow rate control valves 14 and 16 are provided in both the outlet pipe 12 when the travel hydraulic motor 3 moves forward and the exit pipe 11 when the travel hydraulic motor 3 moves backward. However, the gist of the present invention is not limited to this, and it is also possible to set the flow rate control means only in one of the two outlet side pipes 11 and 12. It is.

Although the above embodiment is an example in which a parallel circuit of variable flow control valves 14, 16 and check valves 15, 17 is used as the flow rate control means, the gist of the present invention is not limited to this. All known flow rate control means can be applied as long as the amount of restriction can be adjusted arbitrarily.

[Effect of idea]

The traveling hydraulic motor circuit for a hydraulically driven vehicle according to the present invention brakes the traveling hydraulic motor by reducing the flow rate of the pressure oil supplied to the traveling hydraulic motor in accordance with the amount of depression of the brake pedal.
Accordingly, the load placed on the brake device provided independently of the main travel hydraulic motor circuit can be reduced. Therefore, sufficient braking force can be obtained without using a large-capacity brake device as in the past, and it is possible to downsize the brake device. and,
As a result of reducing the load on the brake device, the service life of the brake is extended, and even if the braking performance of the vehicle is improved, sudden braking becomes possible, which improves safety. Further, since the hydraulic motor circuit for traveling alone has sufficient braking force, it is possible to brake the vehicle even in the event that the brake device fails, and from this point of view as well, it is useful for vehicle safety measures. Note that if the relationship between the amount of depression of the brake pedal and the amount of restriction of the flow rate control means is appropriately designed, it is possible to omit the brake device.
Furthermore, since the throttle amount of the flow rate control means is linked to the brake pedal, and the throttle amount control means of the flow rate control means is operated only when the brake pedal is operated, the flow rate cannot be controlled even when the brake pedal is not operated. If the throttle of the means is initially set to be fully open, the amount of pressure oil supplied to the hydraulic motor for traveling will not be restricted while the vehicle is running, and it is possible to install a fixed throttle valve in the conduit on the outlet side of the hydraulic motor for traveling. Unlike conventional travel hydraulic motor circuits, there is no reduction in driving performance.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing an example of a conventional travel hydraulic motor circuit, Fig. 2 is a circuit diagram showing an embodiment of the present invention, and Fig. 3 is a circuit diagram showing a method of connecting the brake pedal, flow control valve, and brake valve. It is a front view showing an example. 1: Engine, 2: Hydraulic pump, 3: Hydraulic motor for travel, 4: Directional switching valve, 6: Brake valve, 1
1, 12: Outlet side pipe line, 14, 16: Variable flow control valve, 15, 17: Check valve, 18: Brake pedal, 19: Brake operation valve.

Claims (1)

[Scope of utility model registration request] A hydraulic pump driven by an engine, a travel hydraulic motor driven by pressure oil from the hydraulic pump, and a direction switch that controls the pressure oil supplied from the hydraulic pump to the travel hydraulic motor. A hydraulic motor circuit for traveling of a hydraulically driven vehicle comprising a valve, wherein a flow rate control means capable of arbitrarily adjusting the flow rate is interposed in at least one of the two outlet side pipes of the hydraulic motor for traveling, A hydraulic motor circuit for running a hydraulically driven vehicle, characterized in that the throttle amount adjusting means of the flow rate controlling means is linked with a brake pedal of the vehicle.