JPS58206892A - Variable displacement hydraulic device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a variable displacement hydraulic device, specifically a variable displacement pump, a pressure variable throttle valve whose restrictor creases are variable in response to discharge pressure, a position control valve, and a blow compensator. The present invention relates to a variable volume foot type waste pressure device equipped with a valve.

In general, the uJ displacement pump is equipped with a variable control element and an operating plunger for operating the firing element, and the variable control element is controlled by controlling the movement of the bufunja via a pressure compensator valve (hereinafter abbreviated as PO valve). Controlling the elements - p. above.

The capacity side of the pump should be operated based on the set pressure set by the valve.

By the way, the above-mentioned pump capacity control is so-called pressure compensator control using a PO valve, and a long lamp (
Since simple constant horsepower control and constant horsepower control cannot be performed,
In order to perform pressure compensator control of the pump as well as flow rate control such as long ramp system constant horsepower control, a variable throttle valve is interposed in the discharge passage of the pump, and the Pa valve and flow He developed and proposed a variable volume filtration type hydraulic device equipped with a convencator valve (hereinafter referred to as Pa valve). (Special application 1973
5-177752) Specifically, as shown in FIG.
) is interposed with a pressure-type variable throttle valve (20) whose throttle amount is variable in response to the discharge pressure, and a position control valve (60) is installed on the secondary side of this throttle valve (20). ), the Pa valve (40) is connected between the throttle valve (20) and the pump (Mu), and one end is connected to the discharge passage (17).
and the other end is connected to the secondary side of the throttle valve (20) and the downstream side of the position control valve (60), and the pump (
A Pa valve (50) is provided between the 1 Pa valve (40) and the 1 Pa valve (40), with one end communicating with the discharge passage (17).
The a valve (50) and the Pa valve (40) are connected to the control passage (
47), and this passage (47) is connected to the rear chamber (1) of the operation 1 plunger (14) in the pump (M).
4&).

The pressure of the fluid discharged from the pump (A) by L2 is smaller than the pressure set by the Pa valve (50), and the pressure difference between before and after the throttle valve (20) is smaller than the pressure set by the Pa valve (50). 40
), the pressure is lower than the set pressure of the pump (A) without operating the Pa valve (40) and the Pa valve (50), that is, without operating the operation plunger (14) in the pump (A). ) at the maximum flow source, and the load pressure of the fluid increases, causing the throttle valve (2U
), when the differential pressure before and after the throttle valve (20) rises above the set pressure of the 70 valve (40), the 1PO valve (40) is activated and the control passage ( 47) and the Pa valve (50) to the back chamber (14a) of the plunger (14), actuating the plunger (14) and adjusting the amount of fluid discharged from the pump (mu) to al. [In addition, when the fluid discharge pressure reaches the set pressure of the Pa valve (50), pressure compensator control is performed by the Pa valve (50), as shown in the solid line graph in Fig. 4. The aim was to perform constant horsepower control of the pump. This FIG. 4 will be explained in detail later.

By the way, according to the hydraulic device, constant horsepower control as shown in Fig. 4 is possible, but it is not possible to control the device within the characteristic range shown in Fig. 4, and furthermore, it does not have a feathering function. Therefore, when controlling a working machine connected to the secondary side of the position control valve (60), depending on the work process etc., the fourth
Even though flow source control within the characteristic range shown in the figure is sufficient, performing the constant horsepower control resulted in energy loss.The present invention was invented in view of the above problems. The purpose is to use a low pressure sensing type shuttle valve,
By associating the shuttle nose with a position control valve and a variable throttle valve, it is possible to control the pump discharge flow lid within a constant horsepower control range, and it is also equipped with a feathering function to save energy with LIT function. This is what I did.

More specifically, a pressure type U-engineered throttle valve with variable throttle filtration in response to the discharge pressure is installed in the discharge passage of the variable displacement pump, and a position control valve is interposed on the secondary side of the throttle valve. and a flor compensator valve connected to the feedback line communicating with the downstream side of the throttle valve and the primary side of the position control valve; 'ii a low pressure sensing-type shuttle valve with a two-person port and an outlet port;
The first artificial port of the shuttle valve was connected to the discharge passage side of the feedback line, the outlet boat was connected to the valve side, and the second artificial port was connected to the secondary side of the position control valve. The Pa valve (40) is characterized in that by controlling the control valve (60), the Pa valve (40) is controlled via the shuttle valve (70) regardless of the throttle amount of the variable throttle valve (20). Therefore, fL1iii control should be performed within the constant horsepower control range.

The variable displacement hydraulic device of the present invention will be explained below with reference to the actual side of the drawings.

Fig. 1 shows a swash plate type axial piston pump (mm) as a variable displacement hydraulic device.
One drive shaft (4) is supported via bearings (2) and (5), and a pair of cylinder blocks (5) are attached to this drive shaft (4).
, (5) are spline-coupled, and swash plates (6), (6) are connected to each cylinder block (5), (5), respectively.
) is shown.

The device of the present invention can be applied to any variable displacement hydraulic machine including a single pump other than the dual pump shown in FIG.

@1 The hydraulic device shown in the figure is a two-stroke pump, but since the structure is the same, for the sake of explanation, the pump on the left side will be explained.

Therefore, the cylinder block (5') 4i and a large number of pistons (7
) are provided to freely reciprocate, and each of these pistons (7)
On the head of the shoe (
9) are respectively attached, and these shoes (9) are in contact with the swash plate (6).

This swash plate (6) is supported through a trunnion shaft (10) so that it can swing freely within a certain range of inclination angle, and connecting rods (11) and (12) are connected by pins at positions displaced by 180°.
) are connected to a bias plunger (16) that presses the swash plate (6) in the direction of the maximum inclination angle and an operation plunger (14) that adjusts the inclination angle of the swash plate (6). There is.

The bias plunger (16) is an operating plunger (
14) The diameter is smaller than that of the housing (1).
A cylinder (15) fixed to the end cap (1&) of ) is supported freely and a spring (16) is interposed between the cylinder (15) and the head of the plunger (13). Both K, the back chamber (13 &
) communicates with the high-pressure side pressure passage of the pump (A), that is, the discharge passage (17) described later, and the plunger (16)
Further, the operating plunger (14) is movably supported by a cylindrical body (18) fixed to the end cap (1a), and is placed in the rear chamber (14m). A control passage (47), which will be described later, is open so that control pressure acts on the back surface of the operating plunger (14).

Therefore, the control passage (
47), the swash plate (6) reaches its maximum angle of inclination to obtain the maximum discharge lid, and the control pressure is applied to the operating plunger (14). When this occurs, the angle of inclination of the swash plate (6) is adjusted, and a discharge lid commensurate with the angle of inclination can be obtained.

In addition, as shown in detail in FIG.
A pressure variable throttle valve (20) whose throttle amount is variable in response to the discharge pressure is interposed in the discharge passage (17) of the pump (mu), and discharge pressure is applied to one end side. A spool (46) that applies the pressing force of a pressing body (45) made of a coil spring and the load pressure on the secondary side of the throttle valve (20) to the other end side, and the pressing force of the spool (46). An FO valve (40) is provided with the control passage (47) that opens when moved in the direction of the body (45) and communicates with the discharge passage (17), and the control passage (47)
It is connected to the rear chamber (14&) of the operation plunger (14), so that long ramp control or constant horsepower control can be performed.

Further, the throttle valve (20) is located in the discharge passage (17).
) A proportional center-closed position control valve (60) is connected to the load side passage (60), which will be described later, on the secondary side of the
A cylinder (80) is connected to the secondary side of this control valve (60), and the piston of the cylinder (8,0) is actuated by the pressure fluid sent from the throttle valve (20) through the control valve (60). I'm trying to make it happen.

The hydraulic devices shown in FIGS. 2 and 6 are as shown in FIG.
The pressure variable valve ( 20 ) is used to vary the throttle amount in response to pressure and control the flow rate to match the pressure.
The valve body (21) is provided with a spool chamber (22), and the spool chamber (22) includes a spool (26) having a pair of first and second lands (26&) and (23b) at both longitudinal ends.
) is freely movable inside, and a large diameter coil spring (24) with different spring constants is installed outside the first land (2ta).
and a small-diameter coil spring (25) are provided via an adjusting screw (white), and a piston (27) is provided outside the second land (23b), while a piston (27) is provided on the outside of the second land (23b).
1), an annular chamber (2) opening into the spool chamber (22);
8) is provided, and this annular chamber (28) is provided with the discharge passage (
17) to form an orifice (29) between the annular chamber (28) and the second land <2.6b>;
And on the secondary side of the orifice (29), the control valve (
A load-side passageway (60) that constantly communicates with the spool chamber (22) and a feedback line (61) of the 11a valve (40) are connected to the downstream side of the piston (27). A high pressure passage (62) communicating with the discharge passage (17) is connected to the rear chamber (27m).

The springs (24) and (25) are used to set the discharge pressure at which the yO valve (40) starts operating, and the reason why the two springs (24) and (25) are provided is to control the pump. This is to make the characteristics curved in the center as shown in FIG. 4 and to approximate the theoretical constant horsepower characteristics.

That is, the small-diameter coil spring (25) is shorter in length than the large-diameter coil spring (24), and when the discharge pressure is low, the large-diameter coil spring (25) is shorter than the large-diameter coil spring (24).
Only the force 4) acts on the spool (26), and due to the increase in discharge pressure, the small diameter coil spring (25) acts. Then, each spring (24
).

When the pressing force of (25) overcomes the discharge pressure acting on the piston (27), the spool (26-) is moved and the opening degree of the orifice (29) is maintained at the maximum opening degree. When the spool (26) moves due to the increase in the discharge pressure, the opening degree of the orifice (29) H1j decreases, and the flow through the orifice (29) is controlled. This causes the ya valve (40), which will be explained next, to start operating.

Further, the 70 valve (40) is for setting the differential pressure between the discharge pressure and the load pressure constant by the pressing body (45), and detecting the differential pressure between the discharge pressure and the load pressure. As shown in the figure, the spool (46) is movably installed in the spool chamber (42) of the valve body (41) having a spool chamber (42), and the discharge passageway is provided at one end of the spool (46). A communication path (44) communicating with the spool (17) is connected to apply discharge pressure, and the spool (44)
3) The suppressing body (45) is provided on the other end side, and the secondary side of the throttle valve (20) is provided in the accommodation chamber (46) of the pressing body (45) on the downstream side of the control valve (60). While connecting the feedback line (61) that communicates with the valve body (4),
1), the said spool chamber (42) is opened and communicated with the communication passage (44) which is communicated with the discharge passage (17) by movement of the spool (46) toward the suppressor (45). Control! One passage (47) is provided, and in FIG. 2, it is arranged in parallel with the PO valve (50).

This PO valve (50) is for setting the best product pressure, and a spool chamber (51) is provided in the valve body (41) constituting the 70 valve (40) in parallel with the spool chamber (42).
A spool (52) is freely movable inside this spool chamber (51), and one end side of the primary spool chamber (51) is opened to the communication path (44), so that the spool (52)
) A suppressor (56) that applies discharge pressure and is made of a coil spring on the other end and sets the maximum pressure.
A storage chamber (54) is provided in communication with the storage chamber (54).
), the pressing body (56) is provided so as to face the discharge pressure, and the storage chamber (54) is communicated with the tank.

Therefore, the present invention provides a hydraulic device configured as described above, with a pair of first and second artificial ports (71) and (72).
) and one outlet boat (76), and using a low pressure sensitive shuttle valve (70) comprising two first and second valve bodies (74), (75) connected to each other, By interposing the shuttle valve (70) in the piping system of the pump (70), the flow rate is controlled within the constant horsepower control range shown in FIG.

Specifically, as shown in FIG. 6, the first port (71) of the shuttle valve (70) is placed on the discharge passage (17) side of the feedback line (61), and the outlet port) (73) are respectively connected to the FO valve (40) side, and a second artificial boat (72) of the shuttle valve (70) is connected to the secondary side of the control valve (60). By comparing the load-side pressure applied 1 which remains constant due to the operation of (60) and the secondary-side pressure of the throttle valve (20),
If the differential pressure is greater than the spring (76) force,
activating the shuttle valve (70) and communicating the $2 robot (72) with the feedback line (61);
Accordingly, the FO valve (40) is controlled to control the flow rate within the constant horsepower control range.

The present invention is configured as described above, and the pump (A
), the fluid sucked from the suction passage (19) is discharged to the discharge passage (17), and the fluid flowing through the passage (17) is controlled by the variable throttle valve (20) and the position control valve (60).
is sent to the cylinder (80) via the cylinder (80).
) is actuated.

However, if the pressure of the fluid flowing through the discharge passage (17) is lower than the pressure set by the throttle valve (20), and the differential pressure across the throttle valve (20) is lower than the set pressure of the 70 valve (40), The 10th valve (40) is not activated, so the swash plate (6) of the pump (A) is at the maximum angle of inclination, and the maximum flow is discharged from the throttle valve (20), i.e. the 4th valve (40) is inoperative.
As shown in the solid line graph in the figure, in the (&) range H until the set pressure by the throttle valve (20) is reached, the fluid flows out at the maximum flow source.

Further, when the pressure of the fluid flowing through the discharge passage (17) becomes higher than the set pressure N of the throttle valve (20), the opening degree of the orifice (29) is reduced by the movement of the spool (26), and the discharge The pressure in the passageway (17) further increases, and accordingly the ya valve (40) is actuated to operate the operating plunger (14) via the control passageway (47);
The inclination angle of the swash plate (6) is adjusted to reduce the number of discharge devices; that is, in the range (b) of Fig. 4, the yo valve (
Flow compensator control is performed according to 40), and in this range (b), as mentioned above, 1
By interposing two springs (24) and (25) in the 0 valve (40), a curved graph is obtained.

Further, when the fluid pressure in the discharge passage (17) becomes higher and exceeds the pressure set by the PO valve (50), the PO valve (50) is operated and the discharge flow rate is increased through the swash plate (6). is cut off, that is, (
0), pressure compensator control is performed by the FO valve (50).

By the way, when operating the cylinder (80) using the hydraulic device, during the operation, oIJ control valve (
60) may be controlled to narrow the a-section leading to the cylinder (80) or to switch to a closed section.

Now, when the flow rate at point (d) shown in FIG. When the pressure difference of the secondary side pressure (P, ) of the control valve (60) becomes larger than the force of the spring (76), each valve body (74) of the shuttle valve (70) ( 75), but
The shuttle valve (7) is switched upward in FIG.
The second artificial boat (72) of 0) and the outlet boat (76) are communicated, and the secondary side of the control valve (60) is communicated with the ya valve (40). Therefore, the F and O valves (4o) communicate with the downstream side of the throttle valve (20), and the discharge pressure (P), in other words, the downstream pressure (Po) of the throttle valve (20) acts on the F and O valves (4o). one end side and the discharge pressure (P
) A differential pressure is generated between the opposing suppressor (45) and the accommodation chamber (46), and as a result, the discharge pressure (P), that is, the primary side pressure (P, ) is equal to the set pressure of the throttle valve (20). Even if the pressure difference between the outlet side pressure (PI) and the -outlet side pressure (P, ) is activated, and the discharge flow rate of the pump (mu) is reduced from the maximum flow rate to the flow rate at point d in Figure 3.

In FIG. 4, as the discharge pressure (P) increases in region a, the differential pressure (Ps) between the outlet pressure (P, ) and the outlet pressure (Pl) at the throttle valve (20) increases.
'+) increases, even if the control valve (60) is held at a constant opening degree, the flow Ji (Ql
also decreases slightly or enters region b, the differential pressure becomes −°
Since it becomes a pot, a constant flow rate can be obtained regardless of the increase in the discharge pressure ('') until the point e, that is, the constant horsepower line is reached.

Furthermore, if the discharge pressure (P) increases from the pressure at the point e, the secondary pressure (Pl) of the throttle valve (2o) and the secondary pressure (P, ) of the control valve (60) are , if pressure loss is ignored, the pressure will be substantially the same, so the discharge flow rate will change along the constant horsepower line.

In addition, when the control valve (60) described in iiJ is switched to the closed section, the shuttle valve (7o) is opened to the second artificial boat (72) or the tank, so the accommodation chamber of the FO valve (40) is (46) becomes the tank pressure, and the IPO valve (4o) operates to reduce the discharge flow rate of the pump (mu) to zero, making it possible to perform so-called feathering that compensates for the pressure with a low discharge pressure (Pt). .

As described above, by operating the control valve (60) and operating the FO valve (40) via the shuttle valve (70) described in 8ij, the constant horsepower control characteristic of the pump (M) shown in FIG.
In this case, it is possible to control the discharge tiL'fIl of the pump (mu), and feathering is also possible.

As explained above, in the hydraulic system of the present invention, the position control valve (60) is switched and controlled to control the FO valve (FO valve) via the shuttle valve (70) regardless of whether the variable throttle valve (20) is in the
By operating 40), it is possible to perform flow compensation by reducing the flow rate of the pump flow source to a low flow rate within the constant horsepower control range, and therefore, when controlling the working machine connected to the secondary side of the control valve. If it is sufficient to control hot rice within the constant horsepower control range, such as in a work process, the pump can be operated at a flow rate lower than that without constant horsepower control, thereby reducing the consumption of excess pump power. This makes it possible to save energy by eliminating this, and also enables pressure-compensating feathering at low pressure within the constant horsepower control range, further promoting energy savings.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway plan view of a hydraulic system showing an embodiment of the present invention, Fig. iJ2 is a sectional view of its main parts, Fig. 6 is a symbol diagram of the same equipment, and Fig. 4 is a constant horsepower control Characteristic diagram, Fig. 5 is a symbol diagram showing a conventional example (mu)...Pump (17)...Discharge passage (20)...Summer throttle valve (61)...Feedback line (40) )...Flow compensator valve (60)
・・Position control valve (70)・Shuttle valve (71)・1st artificial boat (72)・2nd artificial boat (76)・Exit port agent Patent attorney Tsu 1) Hisashi Nao Figure 4 r

Claims (1)

[Claims] (1) A pressure-type variable throttle valve (20) whose throttle amount is variable in response to the discharge pressure is installed in the discharge passage (17) of the variable displacement pump (mu), and the throttle valve (20) is A position control valve (60) is interposed on the secondary side, and a flow compensator valve (40) is provided, and the valve (40) has the following functions:
A feedback line (6) is connected to the downstream side of the throttle valve (20) and to the downstream side of the position control valve (60)
1) while connecting a pair of first and second artificial boats (
71), (72) and one outlet port (7!l) is provided, and *i inlet water boat 71) of the shuttle valve (70) is connected to the feedback line. (61) to the discharge passage side, and an outlet port (73) connected to the valve side.
A variable volume hydraulic device characterized in that an artificial boat (72) is connected to the secondary side of the position control valve (60).