JP2585656Y2 - Travel hydraulic circuit - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a traveling hydraulic circuit for a hydraulically driven vehicle.

[0002]

2. Description of the Related Art A working vehicle such as an aerial work vehicle, a mobile crane, or the like is driven by hydraulic pressure, and a conventional hydraulic drive circuit for this type of vehicle is: As shown in FIG. 2, a pair of left and right hydraulic motors 2a and 2a for driving left and right drive wheels 2 and 2 of the vehicle 1, respectively, and supply and discharge of driving pressure oil to and from the pair of left and right hydraulic motors 2a and 2a. A serial connection position A where the left and right hydraulic motors 2 and 2 are connected in series and connected to the hydraulic control valve 3 between a single four-way three-position type hydraulic control valve 3 to be controlled; The motor 2 is connected in parallel to a parallel connection position B where the motors 2 and 2 are connected in parallel to the hydraulic control valve 3. In the figure, 5 is a hydraulic pump driven by an engine (not shown), 6 is a hydraulic oil tank, and 7 is a relief valve interposed between the discharge oil passage of the hydraulic pump 5 and the tank 6. The serial / parallel switching means 4 is at the parallel connection position B when the solenoid 4a is not energized, and switches to the serial connection position A when the solenoid 4a is energized .
It is supposed to be. The control of energization to the solenoid 4a is performed by the changeover switch 8.

[0003] vehicle including such a hydraulic drive circuit, both when switching the serial-parallel connection means 4 to the series connection point A or parallel connection position B, by operating the hydraulic control valve 3, the left and right hydraulic motors 2a, 2a The vehicle 1 is driven forward and backward at an arbitrary speed by controlling the supply and discharge of hydraulic pressure for driving the vehicle.

When the serial / parallel connection means 4 is switched to the parallel connection position B, the left and right hydraulic motors 2a, 2a are in a parallel connection state with each other, and the two hydraulic motors 2a, 2a and the left and right drive wheels 2, 2 are connected to each other. Since the differential functions are ensured, even if a difference in rotation occurs between the left and right drive wheels 2, 2 due to the steering of the vehicle, there is an advantage that the two drive wheels 2, 2 can run stably without slipping. is there. In this state,
The hydraulic oil from the hydraulic pump 5 via the hydraulic control valve 3
Since the flow is divided between the left and right hydraulic motors 2a, 2a, it is suitable for traveling at a relatively low speed. That is, in a state where the series-parallel connection means 4 is switched to the parallel connection position B, there is a problem that stable traveling is possible but high-speed traveling is not possible.

When the serial / parallel connection means 4 is switched to the serial connection state A, the left and right hydraulic motors 2a, 2a
Are connected in series, and the entire amount of hydraulic oil from the hydraulic pump 5 passing through the hydraulic control valve 3 passes through each hydraulic motor 2a, 2a, so that it is suitable for traveling at a relatively high speed. However, in this state, there is no differential function between the two hydraulic motors 2a, 2a and the left and right drive wheels 2, 2, and therefore, a rotation difference between the left and right drive wheels 2, 2 during steering of the vehicle 1 or the like. When this occurs, there is a problem that the driving wheels 2 and 2 slip and the traveling becomes unstable. That is, in a state where the series-parallel connection means 4 is switched to the series connection position A, although it is suitable for high-speed traveling, there is a problem that traveling becomes unstable.

[0006]

The object of the present invention is to add a part of the configuration to the above-mentioned conventional traveling hydraulic circuit to switch the series / parallel connection means 4 to the series connection state A for high-speed traveling. In addition, a required differential function is provided between the left and right hydraulic motors 2a, 2a and the left and right drive wheels 2, 2 to provide a traveling hydraulic circuit capable of stable traveling even at high speed. .

[0007]

Means for Solving the Problems To achieve the above object, the traveling hydraulic circuit of the present invention is configured as follows. Between a pair of left and right hydraulic motors that respectively drive the left and right drive wheels of the vehicle, and a single four-way three-position hydraulic control valve that controls the supply and discharge of driving hydraulic oil to the pair of left and right hydraulic motors A serial / parallel switchable switch between a serial connection position where the left and right hydraulic motors are connected in series to the hydraulic control valve and a parallel connection position where the left and right hydraulic motors are connected in parallel and connected to the hydraulic control valve; In a traveling hydraulic circuit having means interposed therein, a bypass oil for interposing an on-off valve between each of the supply and discharge oil passages of the left and right hydraulic motors and for bypassing hydraulic oil restricted in an open state of the on-off valve. A traveling hydraulic circuit which is connected by roads and configured to release the on-off valves of the bypass oil passages in conjunction with the switching of the series / parallel switching means to the series connection position.

[0008]

With the traveling hydraulic circuit according to the present invention configured as described above, when the series / parallel switching means 4 is switched to the parallel connection position B, a stable traveling at a relatively low speed is achieved as in the conventional traveling hydraulic circuit. In the state where the serial / parallel switching means 4 is switched to the serial connection position A, the open / close valve is opened in conjunction with the switching and the left and right hydraulic motors 2a, 2a
a, the restricted hydraulic oil can be bypassed through the bypass oil passages connecting the respective supply / drain oil passages, so that the hydraulic motor 2 and the left and right drive wheels 2, 2 are connected in series, for example.
Even if there is a rotation difference between a and 2a, the hydraulic oil flowing through the bypass oil passage absorbs the rotation difference, and can prevent the left and right drive wheels 2 and 2 from slipping. That is, according to the traveling hydraulic circuit of the present invention, even when the series / parallel switching means 4 is switched to the series connection state A and traveling at high speed, stable traveling can be achieved while suppressing the slip between the left and right drive wheels 2 and 2. It becomes.

When the high-speed running is performed with the serial / parallel switching means switched to the serial connection state A, the steering amount (steering angle) of the vehicle 1 is generally small, and therefore the left and right drive wheels 2 and 2 and the left and right hydraulic pressures are used. Since the rotation difference between the motors 2a and 2a is small, the amount of hydraulic oil passing through the bypass oil passage can be set small. Therefore, the power loss due to the hydraulic oil bypass is small.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the traveling hydraulic circuit of the present invention will be described below with reference to FIG. Since the traveling hydraulic circuit of the present invention is obtained by adding a part of the configuration to the conventional traveling hydraulic circuit shown in FIG. 2 as described above, the reference numerals used in the description of the prior art and the description thereof are as follows. Incorporated into the description.

In FIG. 1, left and right hydraulic motors 2a,
2a is provided with a pair of oil supply / discharge oil passages 9 and 10, respectively, and between the pair of oil supply / discharge oil passages 9 and 10 of the hydraulic motors 2a and 2a, a bypass oil provided with an on-off valve 11 is provided. They are connected by road 12. Each of the bypass oil passages 12 is configured to bypass the restricted hydraulic oil when the on-off valve 11 interposed in the bypass oil passage 12 is open.
Each of the on-off valves 11 is configured by an electromagnetically operated on-off valve that is closed when the solenoid 11a is not energized and is switched to the open state by energizing the solenoid 11a. The solenoid 1 of each on-off valve 11
1a is connected to the changeover switch 8 in parallel with the solenoid 4a of the serial / parallel changeover means 4. When the changeover switch 8 is turned on to set the serial / parallel changeover means 4 to the serial connection state A, the changeover operation is linked. Then, these on-off valves 11 are opened. In the open state of each on-off valve 11, hydraulic oil bypasses through each bypass oil passage 12, but the amount of hydraulic oil to be bypassed is restricted by the throttle valve 13 interposed in each bypass oil passage. ing. This limitation is caused by connecting the serial / parallel switching means 4 to the serial connection state A.
When the vehicle 1 is driven at a relatively high speed, the steering wheel (steering) operation is limited to the minimum necessary to absorb the rotation difference between the left and right drive wheels. ing.

Next, the operation will be described. In the low-speed traveling state in which the series / parallel switching means 4 is switched to the parallel connection position B, the left and right hydraulic motors 2a, 2a are in parallel connection with each other, as in the conventional traveling hydraulic circuit, and the two hydraulic motors 2a, 2a and the left and right Since the drive wheels 2 and 2 have a differential function with each other, even if a difference in rotation occurs between the left and right drive wheels 2 and 2 due to steering of the vehicle, the two drive wheels 2 and 2 do not slip and are stable. It is a vehicle that can run.

In a high-speed running state in which the series / parallel switching means 4 is switched to the series state A, the switching valves 11 and 11 are released in conjunction with the switching to enable a restricted hydraulic oil bypass, thereby enabling steering. Even if a difference in rotation occurs between the left and right drive wheels 2, 2 during (steering) operation, these drive wheels 2, 2 do not slip. Therefore, stable running can be performed even in this high-speed steering state.

In the above embodiment, the series / parallel switching means 4 and the on-off valves 11 and 11 are of a solenoid operated type, and the interlocking between them is performed electrically. Of course, the on-off valves 11, 11 may be of a hydraulic pilot operated type, and the interlocking between them may be performed hydraulically. Further, in the above embodiment, the opening and closing valve 11, 11 which is interposed to each bypass oil passage 12 and 12 are formed separately, these open
Needless to say, the valves 11 and 11 may be integrated.

[0015]

The traveling hydraulic circuit according to the present invention configured as described above has a simple configuration added to the conventional traveling hydraulic circuit, and switches the series / parallel connection means 4 to the series connection state A to perform high-speed traveling. In this case, since the vehicle can run stably, the practical effect is great.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a traveling hydraulic circuit of the present invention.

FIG. 2 is an explanatory diagram of a conventional traveling hydraulic circuit.

[Explanation of symbols]

 Reference Signs List 1 vehicle 2, 2 left and right drive wheels 2a, 2a left and right hydraulic motors 3 hydraulic control valve 4 series / parallel switching means 4a solenoid 5 hydraulic pump 6 hydraulic oil tank 7 relief valve 8 selector switch 9, 10 supply / discharge circuit 11, 11 opening / closing Valves 11a, 11a solenoid 12 bypass oil passage 13 throttle valve

────────────────────────────────────────────────── ─── Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F16H 61/40-61/46 F15B 11/00-11/22 B60K 17/10-17/26 B60K 23 / 00-23/08

Claims (1)

(57) [Scope of request for utility model registration] A pair of left and right hydraulic motors for driving left and right driving wheels of a vehicle, respectively, and a single four-way three-position hydraulic pressure for controlling supply and discharge of driving hydraulic oil to the pair of left and right hydraulic motors. Switching between a serial connection position where the left and right hydraulic motors are connected in series to the hydraulic control valve and a parallel connection position where the left and right hydraulic motors are connected in parallel and connected to the hydraulic control valve between the control valve and the control valve In a traveling hydraulic circuit including a possible series-parallel switching means, a hydraulic oil restricted between the supply and discharge oil passages of the left and right hydraulic motors with an on-off valve interposed therebetween and in an open state of the on-off valve. A traveling hydraulic circuit which is configured to be connected by a bypass oil passage for bypassing the valve and to open and close the on-off valve of each of the bypass oil passages in conjunction with the switching of the series / parallel switching means to the serial connection position. .