JPS6070234A - Construction machine such as power shovel - Google Patents

Abstract

PURPOSE:To turn a rotator with high speeds as an arm or boom cylinder vertically moves together with the motion of a slewing body by a method in which when a motor for slewing and an arm or boom cylinder are concurrently operated, an oil path to the arm or boom cylinder is throttled. CONSTITUTION:A normal closed type switching valve 14 for slewing and a switching valve 15 for arming or booming are connected in parallel with an oil- pressure pump 11. A normal open-type two-way valve 20 serves to allow or limit the supply of pressure oil from the oil-pressure pump 11 to the valve 15 for arming or booming. When a motor 5 for slewing and the arm or boom cylinder 7 are concurrently operated, the oil path to the arm or boom cylinder 7 is throttled by the valve 20, the amount of pressure oil to supply to the arm or boom cylinder 7 is properly secured, and great amounts of high-pressure pressure oil to the motor 5 for slewing are also secured.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to the improvement of construction machines such as power shovels that are equipped with at least a swing motor J3 and an arm or boom cylinder. .

(Prior Art) Conventionally, as this type of construction equipment such as a power shovel, one disclosed in, for example, Japanese Utility Model Publication No. 53-3605 is known. This item, as shown in Figure 2,
At least the rotating sill (a) and the arm cylinder (b)
), the hydraulic circuit includes two hydraulic pumps (C) and (d), and each hydraulic pump (
c), (d) respectively receive pressurized oil supply (J-cock <e), , (f), and one of the switching valve blocks (e) is equipped with an arm switching valve (( 1) and the swing switching valve (h) are connected in parallel to the hydraulic pump (C), and when the two switching valves (g>, (h') are switched in combination, the hydraulic pump (C) Pressure oil is distributed as appropriate according to each load pressure to simultaneously operate the swing motor (a) and the arm cylinder (b).

By the way, the revolving body is rotated and driven by the revolving motor (normally, the model is turned, and it is not until the high load pressure is reached that it gradually turns. Alternatively, the arm or boom, which is the load on the boom cylinder, is lighter than the above-mentioned swing body, and starts to move up and down immediately with a relatively low load pressure.For this reason, in the above-mentioned conventional system, the swing motor (a ) and the arm cylinder (1)), the flow rate of pressure oil from the hydraulic pump (C) is mostly distributed to the arm cylinder (b), and the rotation motor (a)
As a result, the rotating speed of the rotating body is very close to that of the rotating body, and as soon as the arm stops moving, it starts rotating at a relatively high speed for the first time due to the supply of high-pressure oil. It had the disadvantage of poor operability. In particular, when the arm is pulled, the load pressure on the arm becomes almost zero, so the revolving body cannot turn and stops, making the simultaneous operation extremely difficult.

(Object of the Invention) The object of the present invention is to appropriately secure pressure oil supply m to the arm or boom cylinder by constricting the oil passage to the arm or boom cylinder when the swing motor and the arm or boom cylinder operate simultaneously. At the same time, the purpose is to supply high pressure oil to the swing motor in as large a quantity as possible, so that the swinging body can be turned at a relatively high speed simultaneously with the raising and lowering movements of the arm or boom cylinder.

(Structure of the Invention) In order to achieve this object, the structure of the present invention is applied to a machine such as a power shovel that is equipped with at least a swing motor and an arm or boom cylinder, and a hydraulic pump and a hydraulic pump. A normally closed type swing switching valve J5 and an arm or boom switching valve connected in parallel, and soil 51. ! It is equipped with a normal oven type two-way valve that allows or restricts the supply of pressure oil from the hydraulic pump to the arm or boom switching valve, and the swing switching valve communicates with the tank when in the neutral position, and when in the switching position. Sometimes, the two-way valve has a negative pressure detection port 1 to detect load pressure, while the two-way valve has a spring chamber communicating with the tank, and a load pressure detection port of the swing control valve (14) opposing the spring chamber. has a frontage of 1:1 and 1:1 and 1:1 and 1:1 and 1:1, respectively, and when the swing switching valve is in the neutral position, the pressure acting on the pylon 1 of the two-way valve and the spring pressure is made equal to the spring chamber. The two-way valve is operated by spring pressure, and when in the switching position, the two-way valve is switched by load pressure to narrow the oil passage to the arm or boom cylinder.

(Effects of the Invention) Therefore, according to the present invention, when the swing switching valve and the arm or boom switching valve connected in parallel to the hydraulic pump are operated in combination, the swing switching valve is operated in accordance with the switching operation of the swing switching valve. Since the oil passage to the arm or boom cylinder is narrowed by switching between The rotating body can be rotated at a relatively high speed at the same time as the vehicle is lowered by 1τ, and simultaneous operations can be performed in one direction or two.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings.

Figure 1 shows the hydraulic control circuit for a power shovel among various construction machines.
Each actuator for driving the buckets 1 to 4 and the lower traveling body (not shown), namely, the swing motor (5), the boom cylinder (6), the arm cylinder (7), and the bucket 1 to
Schilling (8) Left and right travel motors (9), <10
), and its configuration can be roughly divided into four types:

First and second variable displacement hydraulic pumps (11) supply pressure oil to the motors (5) to (10).

(11'), and a first d having directional switching valves (13) to (18) for switching the direction of fluid supply to each actuator (5) to (1o).
3 J: and second switching valve block (a).

It consists of (b).

The first switching valve block (a) includes a right travel switching valve (13), a swing switching valve (14), an arm switching valve (15), and a two-way valve (20) which is important in the structure of the present invention. ), and the second switching valve block (b) includes a left travel switching valve <16>, a boom switching valve (17), and buckets 1 to 1.
A switching valve (18) is provided for each. When each of the six switching valves (13) to (I 8 ) switches from the neutral position to each of the upper and lower switching positions in the figure, the flow rate is such that throttles (13a) to (18a) with corresponding opening degrees are formed. It is depicted as a directional control valve, and each side change valve (13)
~ (-18) is a load pressure detection boat (13b) that detects the load pressure simultaneously in each of the nine maneuvers.

(13C) to (18b >, <18c) are formed,
The load pressure detection boards 1 to (13b), (13c) to (1
811> and (18c) are in communication with each other when in the neutral position, and when the switching valves in the same switching valve block 1] are in the neutral position, they are connected in each switching valve block (a) and (b), respectively. It communicates with the tank (23) via provided pilot passages (21>, <22).

On the other hand, the two hydraulic pumps (11) and (11') of the pump unit (12) respectively operate the swash plates (11a) and (1'la'), which are normally at the maximum inclination position, and the swash plates (11a) and (1'la'), respectively.
11a>, (1ja') are used to control the inclination according to the input oil pressure (11b), (11b').
)have.

In addition, the pump unit (12) (indicates each hydraulic pump (
11), (11') are provided with load sensing valves (24>, (24'')) that control the discharge amount according to the load. 414, therefore, only one load sensing valve (2/I) will be explained below, and the explanation of the other will be omitted by adding "'" to the same symbols for the same parts. , load sensing valve (24> is 1
The non-control position of the constant horsepower control valve (31) described in j2 <318
)ll'+ is the discharge m control section (11) of the hydraulic pump (11).
13) into the tank (25) ('24a)
), and a control position Tl-24 that feeds back the discharge pressure of the hydraulic pump (11) to the discharge controller (111).
b), and has a spring chamber (24) at one end.
, C) has a predetermined spring pressure (PSI) (for example, 6kq/
A spring (24d) is disposed in the spring chamber (24G), and the highest pressure among the load pressures of the actuator acting on the cock (a) of the first switching valve is disposed on the side wall of the spring chamber (24G). [-le valves (70), (71).

The pilot passage selected and introduced by (72) (
26) One end is open. On the other hand, the spring chamber (24,0
) The pilot room (24e) that opposes the hydraulic pump (
11) discharge pressure is acting.

Therefore, each switching valve (1) of the first switching valve C block (A)
3) to <15) are all in the neutral position, each load pressure detection boat (13b), (13c) to (15b)
), (15C) (7) Due to the leakage to the tank <23), the spring chamber (24c)' is opened to the tank (23), and in this state, the discharge pressure of the hydraulic pump (11) reaches the spring pressure (PSI).
)J: When the discharge pressure increases, the control position (2/
lb), and feed back the discharge pressure to the discharge amount control section <1111) of the hydraulic pump (11).1. Swash plate (
By controlling the head angle of 11a) in the upright direction, the discharge ■
On the other hand, when any switching valve is switched to the switching position, the load pressure detected by the load pressure detection boat is sent to the spring chamber (24) via the pilot passage (26).
c), and in this state, the discharge pressure is applied to the spring chamber (2).
4c)) Total pressure P (load pressure → - spring pressure (Ps
i)) When the total pressure P causes the open position <
By opening the discharge amount control section (11b> of the hydraulic pump (11) to the tank 25), the swash plate (11a) is positioned at the maximum inclination angle position and the discharge amount is maximized. - When the discharge pressure of knob 1 is higher than the total pressure P, the discharge pressure causes the control position (24b) to be positioned (
By repeatedly controlling the tilt angle of the swash plate (11a) in the upright direction to avoid reducing the discharge amount, the pressure difference before and after the throttle of the switched switching valve is maintained at the spring pressure (PSI), and the discharge is increased. The flow rate is controlled to a flow rate according to the opening degree of the switching valve.

In addition, each switching valve (1) of the first switching valve block (a)
3) to (15) are the discharge passages (11C) of the hydraulic pump (11).
) are connected in parallel with each other, and the second
Each switching valve (16) to (18) of the switching valve block (b)
Similarly, the six switching valves (13) to (18) are connected in parallel to the discharge path (11'C) of the hydraulic pump (11'), and each of the six switching valves (13) to (18) is connected to the pump port 1 when in the neutral position. There are 114 normally closed types that close (P+) to (P6).

The two-way valve (20) of the switching valve block (a) is connected to the arm switching valve 15 from the first hydraulic pump (11).
), and there is a communication position (20a) in its interior that communicates the pump passage (50) and a predetermined opening for opening the pump passage (50). The spring chamber (2ρ
C) is compressed with a spring (20d) having a predetermined spring pressure (PS2), and the spring chamber (20c) is communicated with the tank (52) via a pilot passage (51). On the other hand, the maximum pressure among the load pressures for right running and turning is introduced into the pilot chamber (20e) opposing the spring chamber (20C) through the pylon 1 to the passage (53).
The pylon 1 to the passageway (26a) is open.

Additionally, the pump unit 1-(1'2) is equipped with a hydraulic pump (11
), (11') are controlled by the constant horsepower control valve (3
1), <31') are provided. Each of the horsepower control valves (31) and (31') is connected to a hydraulic pump (11).
), (11') Discharge control section (11b), (11b
' ) to tank (25).

(25') non-controlled position (31a) open to (25');

(31a'), and the discharge pressure is adjusted to the above discharge m control i11 part (11
b), (11b') at the control position (31b)
), (311]' ), and the hydraulic pump (
11), (11') swash plate (11a).

A variable set pressure spring (31c) whose spring pressure is set to a high pressure in response to the inclination control of the spring (<118') in the upright direction;
31c'). In addition, (55) is a two-way valve provided in the switching valve block (a), which is normally in the shutoff position (55a), while the boom switching valve (17)
At the lower switching position in the figure, the switch is switched to the communication position (55b) and the pressure oil from the first hydraulic pump (11) is transferred to the head side of the boom cylinder (6) via the two-way valve (55). It is intended to supply Furthermore, (56) and (
Reference numeral 57) indicates first and second two-way valves provided in the switching valve block (b), and the first two-way valve (56), like the two-way valve (55) above, is normally On the other hand, when the arm switching valve (15) is in the lower switching position in the figure, it is switched to the communication position (56b), which allows pressure oil to flow from the second hydraulic pump (11'). the first two-way valve (5
6) to the C-arm cylinder (7), and the second two-way valve (57) is normally in the communication position (57a).
On the other hand, when any switching valve in the switching valve block (b) is switched to the switching position, it is in the shutoff position I! (57b), from the second hydraulic pump (11') to the first two hydraulic pumps (57b).
This prevents the supply of pressure oil to the 1C arm cylinder (7>) via the direction valve (56). In addition, (32) is a prime mover that drives the hydraulic pumps (11) and (11').

Therefore, in the above embodiment, the swing switching valve (1
4) and the arm switching valve (15) are connected to the first hydraulic pump (
11) are connected in parallel to each other, so when both switching valves (1/I) <15) are operated simultaneously, the pressure oil r: from the first hydraulic pump ('+1) is divided. The flow is simultaneously supplied to the swinging morph (5>) and the arm cylinder (7). At this time, the load pressure of the swinging body (1) is detected by the switching operation of the swinging switching valve (14). Bow 1-
<14.11) and acts on the springs 1 to 20 (+) of the two-way valve (20), and the two-way valve (20) detects the spring (20c) in the spring chamber (20c) due to the load pressure of A. 20d
) is switched from the communication position (20a) to the throttle position (20b), and the pump passage (50) from the first hydraulic pump (11) to the arm cylinder (7) is opened to a predetermined degree. [It is narrowed down. For this reason, the first hydraulic pump (1
Most of the pressure oil from 1) is supplied to the rotating circle motor (5) via the rotating switching valve (14), and the load pressure on the rotating body (1) becomes greater than the load pressure on the arm (3). As a result, the load pressure of this rotating body (1) is reduced by the seal valve (7).
When the first hydraulic pump (11) is selected in step 1) and acts on the spring chamber (24C) of the load sensing valve (24), the first hydraulic pump (11) is activated at a high discharge pressure in a short time by controlling the discharge amount of the load sensing valve (24). Each time, a flow M of pressure oil is discharged according to the discharge pressure. Of this pressure oil, the high-pressure oil between the rows is supplied to the swing motor (5) via the swing control valve (14), and at the same time, the remaining pressure oil is depressurized by the two-way valve (20). After that, it is supplied to the arm cylinder (7) via the arm switching valve (15). As a result, the rotating body (1
) begins to rotate relatively quickly, and at the same time the arm (
3) will gradually begin to move up and down. Therefore, it is possible to prevent the swing 1 ho (1) from stopping or turning at low speed at the initial stage of simultaneous operation of the rotating body (1) and the arm (3), thereby improving the simultaneous operability thereof.

In the above embodiment, the present invention is applied to the simultaneous operation of the swing motor (5) and the arm cylinder (7), but the boom cylinder (6) and the arm cylinder (7) may be used instead of the arm cylinder (7). Of course, the present invention can also be similarly applied to simultaneous operation with the turning motor (5).

In the above embodiment, the loading valve (24)
Although the case has been described in which the present invention is applied to a hydraulic control circuit having a variable displacement pump (11) whose discharge amount is controlled by Of course, the same can be applied.

However, in the case of the above embodiment, power loss can be reduced, which is more preferable.

[Brief explanation of the drawing]

FIG. 1 is a hydraulic control circuit diagram showing an embodiment of the present invention, and FIG. 2 is a hydraulic circuit diagram showing a conventional example. (5)...Swivel motor, (7)...Arl) cylinder, (11)...Hydraulic pump, (14)...Swivel switching valve, (14b)...Load pressure detection Boat, ('I
5)...Arm control valve, (20)...2-way valve, (20C:1...spring chamber, (20G)...bar r
Lot room, (23). (52)...Tank.

Claims (1)

[Claims] (1) In a construction machine such as a power shovel that is equipped with at least a swing motor (5) and an arm or boom cylinder (7), a hydraulic pump ('+1) is connected in parallel to the hydraulic pump M1). From the normally closed type swing control valve (14) and the boom control valve (15) and the above hydraulic pump (11) to the arm or arm control valve (15) The pressurized oil supply is controlled by a normally open type two-way valve (20) that limits the capacity or restriction, and the above-mentioned swing switching valve (14) is connected to the tank (23) at the time of purchase. , Negative pressure detection board 1 to (141]) that detects the load pressure when in the switching position
On the other hand, the two-way valve (2d) has a spring chamber (20C) that communicates with the tank (52), and a load pressure detection boat (20C) of the swing switching valve (14) that opposes the spring chamber (20c).
14b) Construction machinery such as a power shovel characterized by having a pilot chamber <20 (right side) with the same opening.