JP2599775B2 - Backhoe working vehicle hydraulic circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a pump oil passage that connects an ascending hydraulic chamber and a descending hydraulic chamber of a double-acting cylinder that raises and lowers a working device to and from a machine body through an operation valve. To a hydraulic circuit of a backhoe working vehicle, which is configured to be separately connectable to a hydraulic pump and a tank oil passage.

[Conventional technology]

In the hydraulic circuit of this type of backhoe working vehicle, it is necessary to lower the working equipment during digging work, and if an emergency stop is attempted, the entire working vehicle causes a “gable phenomenon” and the boom vibrates back and forth. The driving situation of the worker was not so good.

Therefore, conventionally, as shown in the hydraulic circuit diagram of FIG. 2 of JP-A-60-211522, for example, the lowering hydraulic chamber of the double-acting cylinder is connected to a pump oil passage, and When the working device is lowered by separately connecting to the tank oil passage, a throttle mechanism is provided in the oil passage between the raising hydraulic chamber and the operation valve, and is set to match the operating speed at the time of ascent. In this case, the reference oil volume was reduced when the descent occurred.

For this reason, it is possible to reduce the amount of supplied oil, and even if it is stopped during descent, the extreme vibration phenomenon can be suppressed, but the oil temperature rise due to the throttle will increase this time, and the problem of early deterioration of the hydraulic oil will occur. Have been.

SUMMARY OF THE INVENTION An object of the present invention is to provide an apparatus capable of reducing the amount of oil when a working device is lowered without causing an increase in hydraulic pressure.

[Means for solving the problem]

The hydraulic circuit of the backhoe working vehicle according to claim 1 of the present invention is configured such that an ascending hydraulic chamber and a descending hydraulic chamber of a double-acting cylinder that raises and lowers a working device with respect to a machine body are connected to a pump oil passage via an operation valve. In a hydraulic circuit of a backhoe working vehicle configured to be separately connectable to a tank oil passage, an auxiliary return oil passage for returning a part of oil from the pump oil passage to the tank is provided, and each of the operation valves is provided. A port for the auxiliary return oil passage is installed at an operation position, and among the operation positions of the operation valve, the lowering hydraulic chamber of the double-acting cylinder is connected to the pump oil passage, and When a throttle mechanism is provided only in the auxiliary return oil passage at the lowering operation position where the hydraulic chamber is connected to the tank oil passage, and when the operating device switches the operation valve to the lowering operation position where the working device descends with respect to the machine body. Pump automatically, Wherein configuration in that the road are configured to be connected to said lowering hydraulic chamber and the auxiliary return oil passage.

A hydraulic circuit for a backhoe working vehicle according to a second aspect of the present invention includes a boom operating valve, a backhoe operating valve for at least one of a bucket and a swivel base, and a first traveling for one of the left and right traveling devices. A control valve and a hydraulic pump are connected in parallel, and a center bypass path of a multiple valve including the boom control valve, the backhoe control valve, and the first travel control valve is connected to a tank. A hydraulic circuit for a backhoe working vehicle, wherein a throttle mechanism for restricting return oil in a center bypass path is provided only at a lowered operation position of the boom operation valve, and the backhoe operation valve and the first traveling operation valve are provided. In the movable operation position other than the neutral position in the above, a mechanism for preventing the oil from flowing into the center bypass path is provided.

The operation and effect of the features of the first and second aspects are as follows.

[Action]

According to the configuration of the first aspect, that is, when the working device is lowered, the operation is performed such that the pump oil passage, the tank oil passage, and the auxiliary return oil passage are connected to the lowered operation position of the operation valve. The oil that has passed through the pump oil passage is introduced into the descending hydraulic chamber by the operation valve, and the oil in the ascending hydraulic chamber is introduced into the tank oil passage through the operation valve and is discharged. In this case, since the pump oil passage is also connected to the auxiliary return oil passage, the pump oil passage is discharged by an amount corresponding to the throttle formed in the auxiliary return oil passage at the lowering operation position, and the amount of input to the lower hydraulic chamber is small. Become.

According to the second aspect of the present invention, a part of the oil from the pump is returned to the tank through the center bypass which connects the multiple valve as an auxiliary return oil to the tank separately from the tank oil. This has the same effect as the first aspect, and in the case of a combined operation in which the bucket is operated while lowering the boom, for example, the inflow of oil into the center bypass passage is prevented, so that the pump oil amount is reduced. The entire amount is distributed to the boom cylinder and the bucket cylinder, and it is possible to prevent a decrease in the amount of input oil due to outflow from the center bypass passage.

〔The invention's effect〕

Therefore, according to the configuration of the first aspect, the amount of oil that is supplied to the lowering hydraulic chamber when the working device is lowered can be reduced, so that the lowering speed can be reduced and only a part of the discharge amount of the hydraulic pump can be reduced. The oil discharged from the raising hydraulic chamber is discharged to the tank as it is only by discharging while restricting the pressure, so that unnecessary temperature rise can be suppressed.

According to the second aspect of the present invention, the bucket can be operated while lowering the boom, for example, while allowing the partial discharge from the center bypass path only when the boom is lowered to achieve the same effect as the first aspect. In the case of such complex work, partial release of the pressure oil is prevented, and a useful hydraulic circuit capable of sufficiently performing the complex work can be provided.

〔Example〕

 Next, examples will be described.

As shown in FIG. 3, the turning table (2) and the dozer device (3) are attached to the crawler type traveling device (1), and the backhoe device (4), the boarding operation unit (5) and the driving unit (6) are turned. A small backhoe working vehicle that is attached to the base (2) and that can perform earth removal work is configured.

Traveling device (1), swivel (2), dozer device (3),
The hydraulic circuit for driving the backhoe device (4) and the like will be described in detail below with reference to FIG.

The first to third pumps (P ₁ ),
(P ₂ ) and (P ₃ ) are arranged in conjunction with the same engine, and the first traveling control valve (V ₁ ) of the hydraulic motor (M ₁ ) for one of the left and right crawlers and the hydraulic cylinder (4a) for the boom (4a) C ₁₎ of the operating valve (V _2), a bucket (4c) for the hydraulic cylinder (C ₂₎ of the operating valve (V ₃₎ of the first pump in the center multiple-valve type with bypass arranged in this order (P ₁ ) Are connected in parallel. Hydraulic motor (M ₂ ) second travel operating valve (V ₄ ), boom speed-up operating valve (V ₅ ), merging spacer (7), hydraulic cylinder (C ₃ ), The operation valve (V ₆ ) and the operation valve (V ₇ ) for the service port (8) are arranged in that order, and a multiple valve with center bypass
An operating valve (V ₈ ) of a swing hydraulic cylinder (C ₄ ) that is connected in parallel to the pump (P ₂ ) and swings the backhoe device (4) left and right with respect to the swivel table (2), motor (M ₃₎ of the operating valve (V _9), the operating valve of the dozer hydraulic cylinder (C ₅₎ and (V _10), in the center the multiple-valve type with bypass arranged in this order third pump (P ₃₎ Are connected in parallel. Here, the bucket (4c) of the backhoe device (4) corresponds to the working device.

A center bypass as an auxiliary return oil passage of the first multiple valve including the boom / bucket operation valves (V ₁ ), (V ₂ ), and (V ₃ ) as the first traveling and backhoe operating valves. road (11), through a confluence switching valve (V ₁₁₎ tank (T)
To the tank oil passage (9) leading to the oil drainage system.

Here, a throttle mechanism (12) that throttles the oil branched from the pump oil passage (10) to the center bypass passage (11) is provided at the “down operation position” of the boom operation valve (V ₂ ) as a working device. ) Is provided, and when the boom (4a) is lowered, a part of oil is branched from the pump oil passage (10) to the center bypass passage (11) and discharged. Most of the remaining oil is supplied to the lowering oil chamber (a) of the double-acting boom operating hydraulic cylinder (C ₁ ). The center bypass path (1
1) is referred to as an auxiliary return oil passage that returns a part of the oil from the pump oil passage (10) to the tank (T).

As described above, the boom operation valve (V ₂ ) is provided with the throttle mechanism (12) that throttles the oil passing through the center bypass path (11) at the “down operation position”. The operating valve (V ₁ ) and bucket operating valve (V ₃ ) are in the “neutral position”
At other “movable operation positions”, a mechanism is provided for preventing the oil from flowing into the center bypass path (11). That is, the port corresponding to the center bypass path (11) is a closed port. Therefore, during a combined operation in which the boom (4a) and the arm (4b) are simultaneously operated, even if the boom (4a) is being lowered, no oil is discharged from the center bypass path (11) and the total oil amount is reduced. It is distributed to each cylinder. Therefore, there will be no shortage of oil.

[Another embodiment] A bucket (4c) or an arm (4b) may be employed as a working device to be partially returned to the auxiliary return oil passage (11) from oil from the pump.

The operation valves that constitute the multiple valve may be arbitrarily selected and rearranged.

In the claims, reference numerals are provided for convenience of comparison with the drawings, but the present invention is not limited to the structure shown in the attached drawings.

[Brief description of the drawings]

The drawings show an embodiment of a hydraulic circuit of a backhoe working vehicle according to the present invention, FIG. 1 is a circuit diagram showing a state in which a throttle mechanism is provided in an auxiliary return oil passage, FIG. 2 is an overall hydraulic circuit diagram, FIG. The figure is an overall view of the backhoe working vehicle. (1) ... left and right traveling device, (4c) ... working device, (9)
…… Tank oil passage, (10) …… Auxiliary return oil passage, (11) ……
Auxiliary return oil passage (center bypass passage), (12) ... Throttle mechanism, (V ₁ ) ... First traveling operation valve, (V ₂ ) ... Boom operation valve, (T) ... Tank, ( P ₁ ) Pump, (a)
Hydraulic chamber for lowering, (b) Hydraulic chamber for raising, (C ₁ )
… Double acting cylinder.

Claims (2)

(57) [Claims] An ascending hydraulic chamber (b) and a descending hydraulic chamber (a) of a double-acting cylinder (C ₁ ) for raising and lowering a working device (4C) with respect to a machine body (X) are connected to an operation valve (V). ₂ ) A hydraulic circuit for a backhoe working vehicle, which is configured to be separately connectable to a pump oil passage (10) and a tank oil passage (9) via an oil passage. An auxiliary return oil passage (11) for returning a part to the tank (T) is provided, and a port for the auxiliary return oil passage (11) is installed at each operation position of the operation valve (V ₂ ). Of the operating positions of the valve (V ₂ ), the lowering hydraulic chamber (a) of the double-acting cylinder (C ₁ )
Is connected to the pump oil passage (10), and the throttle mechanism is restricted only to the auxiliary return oil passage (11) at the lowering operation position where the lifting hydraulic chamber (b) is connected to the tank oil passage (9). (1
2) is provided, and when the operating device (4C) switches the operation valve (V ₂ ) to a lowering operation position in which the operating device (4C) lowers with respect to the machine body (X), the pump oil passage (10) is automatically supported by the auxiliary device. A hydraulic circuit for a backhoe working vehicle configured to be connected to the return oil passage (11) and the lower hydraulic chamber (a). 2. An operating valve for a boom (V ₂ ), an operating valve for a backhoe for at least one of a bucket and a swivel, and a first operating valve (V) for one of a left and right traveling device (1). ₁ ) are connected in parallel to a hydraulic pump (P ₁ ), and a multi-unit including the boom operation valve (V ₂ ), the backhoe operation valve, and the first traveling operation valve (V ₁ ) A hydraulic circuit of a backhoe working vehicle in which a center bypass path (11) of a valve is connected to a tank (T), wherein the center bypass path (11) is provided only at a lowering operation position of the boom operation valve (V ₂ ). A throttle mechanism (12) for restricting the return oil of the engine is provided, and at a movable operation position other than the neutral position in the backhoe operation valve and the first traveling operation valve (V ₁ ), the oil to the center bypass passage (11) is provided. Backhoe equipped with a mechanism to prevent Hydraulic circuit of the working vehicle.