JPH0732202U - Flow controller - Google Patents

Abstract

(57) [Summary] [Purpose] The objective is to enable the maximum oil amount of the actuator to be controlled by a simple structure regardless of the oil amount of the pump. [Structure] A spool having a small diameter portion at both front and rear ends and a front and rear land between the front and rear small diameter portions, and an intermediate land, and a front annular groove communicating with the bleed-off control chamber between the front and intermediate lands so that the spool is slidably fitted. And a casing having a meter-in control chamber between the middle and rear lands, an intermediate annular groove communicating with the pump passage, and a rear annular groove communicating with the switching valve via the meter-in control chamber and a discharge passage having a throttle, and the front small-diameter portion. The oil hole in the spool that connects the front pressure chamber to be fitted and the meter-in control chamber, the control passage that connects the rear pressure chamber to which the small rear diameter part is fitted and the downstream side of the throttle, and the spring chamber behind the rear land. The flow rate control device has a compressed spring and a pilot pressure passage for supplying an external pilot pressure to the pilot chamber immediately before the front land.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a flow control device suitable for vehicles for construction machines such as power shovels and cranes.

[0002]

[Prior art]

 As shown in FIG. 2, in the case of controlling a plurality of actuators with one pump 1, if it becomes necessary to regulate the flow rate of only one of the actuators (for example, the turning hydraulic motor 2), conventionally This was done by installing one flow control valve (flow control valves 5, 6) in each of the regulated lines (passages 3, 4). Reference numeral 7 is a pump passage, 8 is a relief valve, 9 is a check valve, 10 and 11 are switching valves, and 12 is a tank. However, in the above-mentioned conventional structure, the two flow control valves 5 and 6 are required, and not only the cost becomes high, but also the pressure of the pump 1 becomes abnormally high. An unstable phenomenon is likely to occur due to the interference between the metering characteristics of the spool of the switching valve 10 and the control of the flow control (flow control valves 5, 6).

[0003]

[The purpose of the device]

 An object of the present invention is to enable the maximum oil amount of the actuator to be controlled by a simple structure regardless of the oil amount of the pump. It is also a part of the purpose of the present invention that the maximum oil amount can be freely controlled by the external pilot pressure.

[0004]

[Constitution of device]

 The present invention relates to a spool having a small diameter portion at both front and rear ends and front and rear lands between the front and rear small diameter portions, and an intermediate land, and a spool is slidably fitted to the spool before the communication with the bleed-off control chamber between the front and intermediate lands. A casing having an annular groove and a meter-in control chamber between the intermediate and rear lands, an intermediate annular groove communicating with the pump passage, a meter-in control chamber and a rear annular groove communicating with the switching valve via a discharge passage having a throttle, and a front small diameter Oil hole in the spool that connects the front pressurizing chamber that fits with the meter-in control chamber, the control passage that connects the rear pressurizing chamber that fits with the rear small diameter part to the downstream side of the throttle, and the spring behind the rear land. This is a flow control device consisting of a spring compressed in the chamber, a pilot pressure passage that supplies external pilot pressure to the pilot chamber immediately before the front land, and a notch with a front opening provided on the outer periphery of the first half of the intermediate land.

[0005]

【Example】

 The flow control valve 15 of FIG. 1 includes a spool 16 and a casing 17 into which the spool 16 is slidably fitted. The spool 16 has front and rear end portions (left and right end portions in FIG. 1) of the same small front diameter portion 18, and rear small diameter portion. Portion 19, and a front land 20, a rear land 21, and an intermediate land 22 between the front and rear small-diameter portions 18, 19 are concentrically provided, and the casing 17 has a bleed-off control chamber between the front and intermediate lands 20, 22. 23, a front annular groove 24 communicating with 23, a meter-in control chamber 25 between the intermediate and rear lands 22, 21 and an intermediate annular groove 26 communicating with the pump passage 7a, a meter-in control chamber 25, a throttle 27, and a check valve 28. A rear annular groove 31 communicating with the turning switching valve 30 via a discharge passage 29 having a front pressure chamber 32 into which the front small diameter portion 18 is fitted, and a rear pressure chamber into which the rear small diameter portion 19 is fitted. And 33. Further, the spool 16 is provided with a diametrical hole 34 connecting the meter-in control chamber 25 and the front pressurizing chamber 32 and a central hole 35 (oil hole) communicating with the hole 34, and the intermediate land 22 is provided with a front opening notch 36 in the front half portion. And a rear opening notch 37 at the rear end. 38 and 39 are inner land.

The pump passage 7 a branches from the pump passage 7 and has a check valve 42. The pump passage 7b downstream of the pump passage 7 communicates with the front annular groove 24. The bleed-off passage 43, one end of which is connected to the front annular groove 24, communicates with the tank 12 via switching valves 44 and 45. The intermediate annular groove 26 communicates with the switching valve 44 via a passage 47 having a check valve 46. The switching valve 44 communicates with a cylinder 50 which is another actuator via passages 48 and 49. The control passage 51, which branches from the discharge passage 29 between the throttle 27 and the check valve 28, communicates with the rear pressurizing chamber 33. A coil spring 53 is contracted in a spring chamber 52 behind the rear land 21, and the spring chamber 52 communicates with the tank 12.

The pilot chamber 56 immediately before the front land 20 is connected to an electromagnetic proportional valve 58 via a pilot pressure passage 57, and the electromagnetic proportional valve 58 communicates with a pump 60 via a pump passage 59. Reference numeral 61 is a relief valve. When the solenoid proportional valve 58 is operated by, for example, a lever (not shown) in the cockpit, the hydraulic pressure that increases in proportion to the increase of the scale of the lever can be supplied to the pilot chamber 56, and can be supplied to the pilot chamber 56. When the hydraulic pressure increases, the elasticity of the coil spring 53 is relatively decreased, and the set pressure of the flow control valve 15 is decreased. Reference numeral 62 is a return passage, 63 is a hydraulic pressure take-out passage branched from the pump passage 7a, and a check valve 64 is provided in the middle thereof and communicates with another purpose switching valve 65. 66 is a switching valve for another actuator.

FIG. 1 shows the neutral state. The hydraulic oil pressurized by the pump 1 is supplied to the pump passage 7, the switching valve 66, the pump passage 7b, the front annular groove 24, the bleed-off control chamber 23, and the bleed-off passage. It is discharged to the tank 12 via 43 and the switching valves 44 and 45. When the switching valve 30 is switched to, for example, the b position, the pump passage 7b is shut off, and the pressurized hydraulic oil is throttled from the check valve 42, the pump passage 7a, the intermediate annular groove 26, the meter-in control chamber 25, and the rear annular groove 31. 27, the discharge passage 29 having the check valve 28, the switching valve 30, and the hydraulic fluid supplied to the hydraulic motor 2 through the passage 3 and discharged from the hydraulic motor 2 pass through the passage 4, the switching valve 30, and the return passage 62. After that, it is returned to the tank 12. Meanwhile, the depressurized hydraulic pressure on the downstream side of the throttle 27 is supplied to the rear pressurizing chamber 33 via the control passage 51, and biases the spool 16 together with the coil spring 53 forward (to the left in FIG. 1). On the other hand, the high hydraulic pressure in the meter-in control chamber 25 on the upstream side of the throttle 27 is supplied to the front pressurizing chamber 32 through the holes 34 and 35, and the spool 16 is operated in cooperation with the pilot hydraulic pressure supplied to the pilot chamber 56. When the pressure is urged rearward (to the right in FIG. 1) and the differential pressure between the upstream side and the downstream side of the throttle 27 increases by a predetermined amount or more, the spool 16 retracts and the notch 36 passes through the inner land 38 rearward. The intermediate annular groove 26 communicates with the tank 12 through the notch 36, the bleed-off control chamber 23, the front annular groove 24, and the bleed-off passage 43 to discharge excess hydraulic oil, and when the balance is reached, the spool 16 stops, The flow rate of hydraulic oil passing through the throttle 27 becomes constant. When the pilot pressure in the pilot chamber 56 is reduced by the solenoid proportional valve 58, the set pressure of the flow control valve 15 increases and the flow rate of the hydraulic oil passing through the throttle 27 increases. When the pilot pressure in the pilot chamber 56 is increased, the flow rate increases. The set pressure of the control valve 15 decreases and the flow rate of the hydraulic oil passing through the throttle 27 decreases.

As described above, in the present invention, the meter-in control flow control valve (flow control valve 15) is arranged in the parallel line in front of the spool valve (switching valve 30) that controls the actuator (for example, the hydraulic motor 2). However, a flow control valve that allows bleed-off control with the same flow control spool 16 was installed. When the flow control is in the control state, the excess oil of the pump oil amount is configured to escape from the bleed-off control section to the bleed-off line (bleed-off passage 43). In addition, the amount of control oil can be changed by guiding the pilot pressure from the outside to the pilot chamber 56 on the opposite side of the spring chamber 52.

[0010]

[Effect of device]

 (1) The maximum oil amount of the actuator (hydraulic motor 2) can be controlled regardless of the oil amount of the pump 1. (2) The maximum oil amount can be freely controlled by the external pilot pressure. (3) The above (1) and (2) can be performed even in the case of a composite operation.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram.

FIG. 2 is a hydraulic circuit diagram showing a conventional example.

[Explanation of symbols]

 7a Pump passage 16 Spool 17 Casing 18 Front small diameter portion 19 Rear small diameter portion 20 Front land 21 Rear land 22 Intermediate land 23 Bleed-off control chamber 24 Front annular groove 25 Meter-in control chamber 26 Intermediate annular groove 27 Throttling 29 Discharge passage 30 Switching valve 31 Rear annular groove 32 Front pressure chamber 33 Rear pressure chamber 34 Diameter hole (oil hole) 35 Center hole (oil hole) 36 Notch 51 Control passage 52 Spring chamber 53 Coil spring 56 Pilot chamber 57 Pilot pressure passage

Claims (1)

[Scope of utility model registration request] 1. A spool having a small diameter portion at both front and rear ends and front and rear lands between the front and rear small diameter portions, and an intermediate land, and before the spool is slidably fitted to communicate with a bleed-off control chamber between the front and intermediate lands. A casing having an annular groove and a meter-in control chamber between the intermediate and rear lands, an intermediate annular groove communicating with the pump passage, a meter-in control chamber and a rear annular groove communicating with the switching valve via a discharge passage having a throttle, and a front small diameter Oil hole in the spool that connects the front pressurizing chamber that fits with the meter-in control chamber, the control passage that connects the rear pressurizing chamber that fits with the rear small-diameter part to the downstream side of the throttle, and the spring behind the rear land. A flow control device comprising a spring compressed in the chamber, a pilot pressure passage for supplying an external pilot pressure to the pilot chamber immediately before the front land, and a front opening notch provided on the outer periphery of the front half of the intermediate land.