US 4,362,018 A · Hydraulic rotation control circuit

Abstract

A hydraulic rotation control circuit for a rotational actuator such as a hydraulic motor for rotating a rotary frame of a hydraulic crane, the circuit employing a combination of a number of check and variable reducing valves in a manner which allows smooth and delicate control of the rotation of the actuator to provide an operation performance equivalent to that of mechanical drive, including coasting operation of the motor.

Drawings

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Drawings

Claims1

Dependent claims

A hydraulic rotation control circuit operating below a maximum pressure for rotating a rotary body under a driving pressure, comprising

a control valve assembly including a first, second, third and fourth port and first, second, third and fourth passages formed in said assembly wherein the cross sectional areas of said first and second passages are equal;
a first pump connected to said first port communicating with said first passage and producing a maximum pressure;
a first check valve communicating the second port with the second passage and allowing fluid flow from the first passage to the second port and passage;
a second check valve communicating the third port with the third passage and allowing fluid flow from the first passage to the third port and passage;
a third check valve allowing fluid flow from the third passage to the fourth passage;
a fourth check valve communicating the fourth port with the fourth passage and allowing fluid flow from the second passage to the fourth port and passage wherein said fourth check valve is substantially the same structurally and dimensionally as said second check valve such that said driving pressure may be maintained at a substantially constant predetermined level;
a first variable reducing valve communicating with said second and fourth check valves and including means for producing a variable pressure less than said maximum pressure by controlling blocking force of said second and fourth check valves against said first and second passages, respectively;
a second variable reducing valve communicating with said first and third check valves and including means for producing a variable pressure less than said maximum pressure by controlling a blocking force of said first and third check valves against said first and third passages, respectively;
and
a second pump for delivering a pressurized fluid to said first and second variable reducing valves;
a rotary actuator connected to said second and third ports and operable to rotate said rotary body;
a fifth passage formed in said control valve assembly, said control circuit further comprising a fluid storage tank and a fifth check valve, said fifth check valve being disposed in said fifth passage communicating with said fourth port, biased closed by means, and having an opening facing said fourth port such that said fluid flows from said fourth port through said fifth check valve and into said tank;
and
a first auxiliary passage connecting said third port with said fourth passage, a check valve provided in said first auxiliary passage and having an opening facing said fourth passage, a second auxiliary passage means connecting said fourth port with said second port, and a check valve provided in said second auxiliary passage and having an opening facing said fourth port.

11 more elements

Dependencies are inferred from the claim text.

Description3,876 words

Summary707 words

#1. Field of the Invention

#This invention relates to a hydraulic control circuit for an actuator such as a hydraulic motor for rotating a rotary frame of a crane.

#2. Description of the Prior Art

Brief description of the drawings20 words

#In the accompanying drawing:

#The sole FIGURE is a diagram of a hydraulic rotation control circuit embodying the present invention.

Detailed description3,149 words

#Referring to the accompanying drawing, there is shown a hydraulic rotation control circuit according to the invention, including a pump 1, a control valve 2, a motor 3, a rotary body 4, a pump 5, an unload valve 6, an accumulator 7, a first variable reducing valve 8, a second variable reducing valve 9, an operating lever 12, a filter 13 and a fluid storage tank 14. Reference numerals 10 and 11 denote rods of the reducing valves 8 and 9, respectively.

#The pump 1 is a main pump for operating an actuator, in the particular example shown, the hydraulic motor 3 which is employed for turning a rotary body 4, more particularly, a rotary frame of a hydraulic crane. The control valve 2 is provided with four ports 21 to 24, four passages 31 to 34 and four check valves 41 to 44 in its casing. The first port 21 communicates with the main pump 1, the second and third ports 22 and 23 communicate with the output port of the motor 3, and the fourth port 24 communicates with a return passage to the tank 14.

#The first check valve 41 is provided at the intersection of the first passage 31, leading from the first port 21, with the second port 22 and second passage 32, constantly communicating the second port 22 with the second passage 32 while resiliently closing with a spring 51 the open left end of the first passage 31, as seen in the drawing, to allow fluid flows from the first passage to the second port 22 and the second passage 32. The second check valve 42 is provided at the intersection of the first passage 31 with the third port 23 and the third passage 33, constantly communicating the third port 23 with the third passage 33 while closing with a spring 52 the open right end of the first passage 31, as seen in the drawing, to allow fluid flows from the first passage 31 to the third port 23 and the third passage 33.

Facts

Application

06/158,877Filed 12 Jun 1980

Granted

7 Dec 1982

Term ended

12 Jun 2000

Estimated · how

Pre-1995 term; greater of 17 years from grant or 20 years from filing when eligible. Maintenance-fee lapses, terminal disclaimers and statutory extensions have not been checked. The continuity chain may be incomplete; this is not an enforceability determination.

Classification11 codes

F15B 13/0405
Valve members; Fluid interconnections therefor: for seat valves, i.e. poppet valves
F15B 11/0445
By means in the return line: with counterbalance valves, e.g. to prevent overrunning or for braking
F15B 2211/30505
Characterised by the type of valves: non-return valves, i.e. check valves
F15B 2211/355
Directional control: pilot pressure control

Hydraulic rotation control circuit

Life of this patent

Hydraulic rotation control circuit

Life of this patent

Life of this patent

Abstract

Drawings

Drawings

Claims1

Description3,876 words

Drawings

Classification11 codes

Life of this patent

Description3,876 words