JPS5985044A - Construction machine such as power shovel - Google Patents

Abstract

PURPOSE:To improve the interlocking action of a slewing base and a boom by using a system in which discharge pressure oil from a variable-capacity oil- pressure pump is preferentially supplied in parallel to a turning motor and a boom cylinder, and excessive oil is supplied to other actuators. CONSTITUTION:In the oil-pressure circuit of a back hoe A having a slewing base 1, a boom 2, an arm 3 and a bucket 4, the discharge pressure oil of a variable- capacity oil-pressure pump 11 is preferentially supplied in parallel to a turning motor 5 and a boom cylinder 6. The excessive pressure oil is supplied to other actuators 7 and 10 by a preferential type pressure compensating valve 27 provided in the upstream of the discharge pipeline of the oil-pressure pump 11. In concurrently operating the turning motor 5 and the boom cylinder 6, the pressure oil is supplied to the boom cylinder 6 and the turning motor 5 in a parallel manner. The interlocking action of the slewing base and the boom can thus be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a construction machine such as a power shovel, and more particularly to a hydraulic circuit structure that improves the interlock between a rotating body and a boom.

In general, in this type of construction machinery, when the rotating body and other moving bodies (such as booms and arms) operate simultaneously, it is required that the rotating body rotates independently without being interfered with by the operation of the other moving bodies. be done. For this reason, the present applicant first filed a patent application filed in
- In No. 151242, the pressure oil from one hydraulic pump whose discharge amount is controlled is supplied to the swing motor with priority, and the excess oil is supplied to other moving bodies, which requires a pump exclusively for the swing body. We are proposing a device that is small in size and has a simple circuit configuration that satisfies these requirements.

By the way, one of the main operations of construction machinery is excavation work, and in this work, the operation of releasing the excavated soil is performed by simultaneously operating the revolving body and the boom, lifting the packet and rotating it to a dump truck parked nearby. This is done by releasing excavated soil onto the loading platform. However, in the above proposal, pressure oil is supplied to the swing motor with priority, and only surplus oil is supplied to the boom, so the rising speed of the boom is slow, and the height position of the packet is still low when it swings to a predetermined position. low,
It is a matter of regret that the interlock between the revolving structure and the boom is poor.

Therefore, in the first invention of the present application, in view of this point, pressure oil is given priority and supplied to the revolving body and the boom in parallel, and surplus oil is supplied to other moving bodies (for example, arms and packets). By doing so, the purpose is to increase the rising speed of the boom and improve the interlocking nature of the revolving structure and the boom.

In order to achieve the object, the invention No.] provides a revolving body,
A construction machine such as a power shovel that is equipped with a boom and other moving bodies, including a hydraulic pump whose discharge amount is controlled according to load pressure by a load sensing valve, a swing motor, a boom cylinder, and other moving body drives. an actuator for
A priority type pressure compensation valve is provided, which supplies pressure oil from the hydraulic pump in parallel to the swing motor and boom cylinder, and supplies excess oil to actuators for driving other moving bodies. During simultaneous operation, pressure oil is supplied to the swing motor and boom cylinder in parallel.

At that time, if the other moving body to which the surplus oil is supplied is limited to the arm, when the boom and arm are operated simultaneously,
Prioritizing the supply of pressure oil to the boom reduces the amount of pressure oil supplied to the arm, resulting in a disadvantage that the interlocking performance deteriorates.

Therefore, the second invention of the present application maximizes the amount of pressurized oil to the arm when the boom and arm are operated simultaneously by limiting the maximum set flow rate of the boom to below the maximum flow rate of the hydraulic pump. The purpose is to increase the number of users and improve their linkage.

In order to achieve the object, a second invention provides a construction machine such as a power shovel that includes a revolving body, a boom, and an arm, and includes a hydraulic pump whose discharge amount is controlled according to load pressure by a load sensing valve; The system includes a swing motor, a boom cylinder, an arm cylinder, and a priority pressure compensation valve that preferentially supplies pressure oil from the hydraulic pump to the swing motor and the boom cylinder in parallel, and supplies surplus oil to the arm cylinder. When the rotating body and boom operate simultaneously, pressure oil is supplied to the swing motor and boom cylinder in parallel, and the maximum throttle opening of the boom switching valve is adjusted so that the maximum set flow rate is the maximum discharge of the hydraulic pump. 5- or less, to generate as much flow as possible to the arm cylinder when the boom and arm operate simultaneously.

Embodiments of the present invention will be described in detail below with reference to the drawings.

The drawing shows the hydraulic circuit of a power shovel among various construction machines. This hydraulic circuit consists of a revolving body (1), a boom (2), an arm (3), and a packet (
4) and the drive actuators of the undercarriage (not shown), namely the swing motor (5) and the boom cylinder (
6), arm cylinder (7), packet cylinder (8)
and left and right travel motors t9], +to), and its configuration can be roughly divided into two actuators (
5) A pump unit equipped with two variable displacement hydraulic pumps (++) and (n)' that supply pressure oil to (lO)
(+2), and first and second switching valve blocks (a) and (b) having switching valves (13) to (20) for switching the oil feeding direction to each actuator (5) to (10). Become.

The first switching valve block (a) includes a right-hand travel switching valve (13) and a turning switching valve (14), and the second switching valve block (b) includes a left-hand travel switching valve (14). A valve (17) and a packet switching valve (18) are provided. In addition, two switching valves, main and auxiliary, are installed for the boom cylinder (6) and arm cylinder (7) in order to effectively utilize the power of the two hydraulic pumps (II) + (o)'. The first switching valve block (A) includes the auxiliary boom switching valve (15) and the main arm switching valve (1G), and the second switching valve
The switching valve block (b) has a main boom switching valve (+9).
and an auxiliary arm switching valve (20) are provided, respectively. When the eight switching valves (13) to (20) switch from the neutral position to each of the upper and lower control positions in the figure, the flow direction is such that throttles (13a) to (20a) with corresponding opening degrees are formed. It is composed of a switching valve, and each switching valve (13
) to (20) are load pressure detection ports (131) for detecting load pressure at each control position.

03C) to (20b), (20 is formed, and the load pressure detection port (13b), (13c) to (20b),
(20c) communicate with each other when in the neutral position, and when all the switching valves in the same switching valve block are in the neutral position, the pilot passages (21+, Tank via 22+ (
23).

On the other hand, the two hydraulic pumps (u) and (++)' of the pump unit (+2) respectively move the swash plates (lla) and (lla)', which are normally at the maximum inclination position, and the swash plate (l
la), (a discharge amount control unit (111) that controls the inclination of llaγ according to the input oil pressure).

(111) γ.

1, the pump unit (+2) has each hydraulic pump (1
1).

Load sensing valves (241, (24+') are provided to control the discharge amount of (I 1)' according to the load. Since each of the load sensing valves (241, H'U) has the same structure, hereinafter one will be referred to as one. Only the load sensing valve (24) described below will be explained, and the explanation of the other part will be omitted by adding "'" to the same reference numerals.In other words, the load sensing valve (24) is a constant horsepower control valve (described later). (3
1) non-control position ■ open position (24a) in which the discharge amount control unit (1 lb) of the hydraulic pump (11) is opened to the tank (20) at la), and the discharge pressure of the hydraulic pump (11) is controlled as described above. The control position (
24b), and a spring chamber (24b) at one end.
24c) is provided with a spring (24d) having a predetermined spring pressure (pm) (for example, 6~), and the side wall of the spring chamber (24C) is provided with a spring (24d) for any one of the first switching valve blocks (A). One end of a pilot passage (26) is open, through which the highest pressure among the load pressures generated by switching the valves is selected and introduced. On the other hand, the discharge pressure of the hydraulic pump sail acts on the pilot chamber (24e) that opposes the spring chamber (24c). Therefore, when each switching valve (+3) to (16) of the first switching valve block (a) is in the neutral position,
Each load pressure detection port (1, 3a), (13b) ~ (1
-6a).

(113b) to the tank (23), the pilot chamber (24e) is opened to the tank +23), and in this state, when the discharge pressure of the hydraulic pump (!l) becomes higher than the spring pressure (Ps), the discharge By positioning the pump at the pressure control position (241)) and feeding back the discharge pressure to the discharge amount control unit (1, 1b) of the hydraulic pump (11), the swash plate 01a) is tilted in the upright direction. While controlling the discharge amount to approximately zero, when any switching valve is switched to the control position, the load pressure detected by the load pressure detection port is sent to the pilot chamber (24e) via the pilot passage (26). In this state, the discharge pressure is increased to the pilot chamber (24e).
), when the total pressure P (load pressure + spring pressure (Ps)) acting on the hydraulic pump (11) is lower than the total pressure P (load pressure + spring pressure (Ps)), the hydraulic pump (11) is positioned in the open position (24a) due to the total pressure P. llb) to tank (25
), the swash plate 01a) is positioned at the maximum inclination angle position to maximize the discharge amount, while when the discharge pressure is higher than the total pressure P, the discharge pressure causes the control position (24
'b), and by repeatedly controlling the inclination of the swash plate (lla) in the upright direction to reduce the discharge amount,
The pressure difference before and after the throttle of the switched switching valve is determined by the spring pressure (
Ps), and the discharge amount is controlled to a flow rate corresponding to the throttle opening of the switching valve.

On the other hand, on the upstream side of the first switching valve block (r), there is a priority pressure compensation valve 61! η is provided. The priority type pressure compensation valve (27) is connected to a pump boat (2'Ia) to which pressure oil is supplied from the hydraulic pump (11) and a priority boat (2'Ia).
b) and a non-priority bow) (2'/c), and the set flow rate is set according to the throttle opening degree of the switching valve connected downstream of the priority port (271)). 2b) to preferentially distribute the excess oil downstream from the non-priority port (27c
) is configured to be distributed downstream from the Then, the priority type pressure compensation valve (two priority boats (27b)
) On the downstream side, there is a switching valve for right travel (13) and a switching valve for turning (13).
14) and the switching valve (15) for the auxiliary boom are connected in parallel, and the switching valve for the main arm ( 1G) is connected.

Further, the auxiliary boom switching valve (15) of the first switching valve block (a) is configured such that the maximum set flow rate according to the maximum opening degree of the throttle 05a) is equal to or less than the maximum discharge amount of the hydraulic pump (11). In addition, the maximum opening degree of the aperture 05a) is formed to be small.

The second switching valve block (b) is also provided with a preferential expansion pressure compensating valve (28), which gives priority to the pressure oil from the hydraulic pump (ll)' and switches it to the left travel switching valve (17). , the packet switching valve (18) and the main boom switching valve (+9) K, and surplus oil is supplied to the auxiliary arm switching valve (20). In addition, the first switching valve block (a)
There is a pressure reducing valve (29) immediately upstream of the main arm switching valve (16).
is provided. The pressure reducing valve (29) is one of the switching valves (1g), (+4), or (15) connected to the priority side of the arm switching valve (16) and the priority expansion pressure compensation valve (27).
), if the load pressure on the arm (3) is lower, the pressure oil from the priority expansion pressure compensation valve (27) is transferred to the arm (
3) The pressure is reduced to a pressure corresponding to the load pressure. Similarly, a pressure reducing valve (30) is also provided on the upstream side of the auxiliary arm switching valve (20) of the second switching valve block (b).

Furthermore, the pump unit (12) includes a hydraulic pump (river,
Constant horsepower control valve (31+,
(3))' is provided. Each chamber horsepower control valve (3
1) and (31)' are hydraulic pumps (n) and (n
)' discharge rate control part (111)), (11b)/ is opened to the tank (25), (25)' at a non-control position (F
'la)+(play' and a control position ■ that causes the discharge pressure to act on the discharge amount control section (llb), (llb)'.
11)), ■lb)', the hydraulic pump (
11), (variable set pressure spring lc whose spring pressure is set to a high pressure in accordance with the tilt angle control of the river's swash plate (11a), (11a)' in the upright direction), (31cγ) In addition, in Japan, when the maximum load pressure is higher than the set pressure, the load pressure sensitive relief valve opens and relieves the pressure oil in the hydraulic pump (++) and (1+)', and (33) is the hydraulic pump. It is the prime mover that drives (It) and (++)'.

Next, to explain the operation of the above embodiment, the rotating body (
1) and boom (2) at the same time, the swing motor (5)
) is activated by receiving pressure oil from the hydraulic pump (11) when the swing switching valve (14) is switched to the control position, and the boom cylinder (6) is activated by switching the switching valve (14) for both the main boom and the auxiliary boom ( +9), by switching to the control position of (15), the two hydraulic pumps (11), (11)'7
It operates by receiving pressure oil from 5>.

At that time, the load pressures of both are equal because the swing switching valve (14) and the auxiliary boom switching valve (15) are connected in parallel, and the boom (2) is lighter than the swing structure (1). ) is the load pressure. Therefore, the discharge pressure of the hydraulic pump (11) is controlled by the load sensing valve (24).
2) (load pressure + spring pressure (Pa)), and the discharge amount becomes a flow rate according to the discharge pressure. Then, after the entire amount of the pressure oil is supplied to the priority expansion pressure compensation valve (27),
It is supplied from the priority port (2'7b) to the swing motor (5) and the boom cylinder (6) in parallel, and the flow rate distribution is large for the lightweight boom (2) and small for the heavy swing structure +1+. As a result, the operating speed of the boom (2) is fast.1.
In addition, the operating speed of the revolving structure (1) is slow, so when, for example, the excavated soil in the packet (4) is to be discharged onto the loading platform of a dump truck parked nearby, the packet (4) must be moved to the boom (which has a high rising speed). By 2), when it is quickly raised and swung to a predetermined position, it can already be positioned at a predetermined height position, and the interlocking nature of the revolving structure +1+ and the boom (2) can be improved.

In addition, when the boom (2) and arm (3) are operated simultaneously, the boom cylinder (6) is equipped with two switching valves (+9) and (+5) for the main boom and auxiliary boom, which are switched to the control position. Pressure oil from the hydraulic pumps (11), (11)' is supplied preferentially by the preferential expansion pressure compensation valve (2η, (28)), and the arm cylinder (7) has a switch for both main arm and auxiliary arm. By switching the valves (+6) and (20) to the control position, both hydraulic pumps (11, (u)'
Surplus oil is being supplied from

At this time, the discharge pressure of each hydraulic pump (IIL (11)' is determined by the load sensing valve (24), (241') according to the higher pressure of both load pressures, for example, the pressure corresponding to the load pressure of the boom (2). (2) Load pressure + Spring pressure (Pa))
It becomes.

At this time, in the switching valve block (a), the maximum set flow rate of the auxiliary boom switching valve (15) is limited to less than the maximum discharge amount of the hydraulic pump (11) due to the reduction of the maximum throttle opening. , the priority oil supply amount to boom (2) is limited,
As a result, surplus flow is generated as much as possible from the non-priority port (2'7C) of the priority expansion pressure compensation valve +27), and the pressure is reduced to the pressure according to the load pressure of the arm (3) by the pressure reducing valve (29). After that, it is supplied to the arm (3).

As a result, the operating speed of the boom (2) increases due to the preferential supply of pressure oil, and the operating speed of the arm (3) increases due to the possible generation of the surplus oil, so that the boom (2) and the arm (3) It is possible to improve the linkage with

In addition, when the rotating body (1) and the arm (3) are operated simultaneously, especially when the arm (3) is pulled out from the rotation life,
The load pressure on the arm (3) becomes almost zero due to the drop due to the weight of the arm (3), but the swing motor (5) is supplied with pressure oil preferentially by the priority pressure compensation valve (2η). The load pressure on the body [11] is sufficiently high, and the predetermined rotation speed of the rotating body (1) is satisfactorily ensured.

Further, in the above embodiments, the case where it is applied to a power shovel has been explained, but the first and second inventions can be similarly applied to various other construction machines such as cranes. Of course.

As explained above, according to the first invention, since the pressure oil from one hydraulic pump is configured to be supplied preferentially to the swing motor and the boom cylinder l in parallel, It is possible to improve the linkage with the boom, and it is possible to improve the driving performance of the power shovel.

Further, according to the second invention, in addition to the configuration of the first invention, the maximum set flow rate of the boom switching valve is limited to the maximum discharge amount of the hydraulic pump or less, thereby allowing excess flow to the arm cylinder. Therefore, in addition to the effect of the first invention, the interlock between the boom and the arm can be improved, and the driving performance of the power shovel can be further improved. It is something.

[Brief explanation of the drawing]

The drawing is a hydraulic circuit diagram showing an embodiment in which the present invention is applied to a power shovel. (1)...Swivel body, (2)...Boom, (3)...Arm, (5)...Swivel motor, (6)...Boom cylinder, (7)...Arm cylinder, (11)...・Variable displacement hydraulic pump, (I5)...Switching valve for auxiliary boom, (15
a)... Throttle, (24)... Load sensing valve, (2
4a)...open position, (24b), control position, (2
4c) - Spring chamber, (24-d)...Spring, (24e)
...Pilot room, (2'7)...Priority type pressure compensation valve,
(2'7a)...Pump port, (2'2b)...Priority port, (2'7c)...Non-priority port. Patent Applicant: Daikin Industries, Ltd. Representative 1) Hiroshi-1'7-

Claims (2)

[Claims] (1) A hydraulic pump that is a construction machine such as a power shovel that is equipped with a rotating body (1), a boom (2), and other moving bodies, and whose discharge amount is controlled according to load pressure by a load sensing valve (24). (11), a boom cylinder (6),
Another moving body drive actuator and the hydraulic pump (
11) A preferential pressure compensation valve that preferentially supplies the pressure oil to the swing motor (5) and the boom cylinder (6) in parallel, and supplies surplus oil to other moving body drive actuators, When the rotating body [1+ and boom (2) operate simultaneously]
A construction machine such as a power shovel, characterized in that pressure oil is supplied to a swing motor (5) and a boom cylinder (6) in parallel. (2) Swivel body (1), boom (2) and arm (3)
A construction machine such as a power shovel is equipped with a hydraulic pump (II) whose discharge amount is controlled according to load pressure by a load sensing valve (24), a swing motor (5), and a boom cylinder (6). , arm cylinder (7), and the swing motor (5) with priority given to the pressure oil of the hydraulic pump (11).
and a priority expansion pressure compensation valve (which supplies the boom cylinder (6) in parallel and supplies excess oil to the arm cylinder (7)).
27), and when the rotating body (1) and boom (2) operate simultaneously, pressure oil is supplied to the swing motor (5) and boom cylinder (6) in parallel, and a boom switching valve ( 1
5) is set such that the maximum set flow rate is less than the maximum discharge amount of the hydraulic pump (11), and when the boom (2) and arm (3) are operated simultaneously, the arm cylinder (7 ) Construction machinery, such as a power shovel, is characterized by generating as much flow as possible.