JP2005297768A - Full hydraulic type power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a full hydraulic type power steering device capable of expanding/contracting a single rod type steering cylinder with the same characteristic without complicating a steering hydraulic circuit, or introducing any new hydraulic equipment. <P>SOLUTION: One oil chamber 2b of a single rod type steering cylinder 1 is communicated with and connected to one port 4b of a pair of ports 4a, 4b formed in a metering pump 4, the other port 4a of the metering pump 4 is communicated with and connected to one secondary port 3a of a control valve 3 interlocked with a steering handle 7, and the other oil chamber 2a of the steering cylinder 1 is communicated with and connected to the other secondary port 2a of the control valve 3. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fully hydraulic power steering apparatus using a single rod type steering cylinder.

  The all-hydraulic power steering system using a single rod type steering cylinder is advantageous in that it is cheaper and smaller than a double rod type steering cylinder and has a higher degree of freedom when it is mounted on the fuselage. On the other hand, the left and right steering characteristics differ depending on the piston area difference between the bottom side and the rod side.

Therefore, for example, as disclosed in Patent Document 1 or Patent Document 2, a technique has been proposed in which the characteristics of the steering cylinder are equalized when the steering cylinder is extended and shortened by controlling the flow rate to the steering cylinder. Has been.
Japanese Utility Model Publication No. 2-44613 JP-A-7-205823

  As described above, by controlling the flow rate to the steering cylinder, the means for aligning the characteristics when the steering cylinder is extended and shortened, the hydraulic circuit for the steering becomes complicated, the flow divider valve mechanism, etc. It was necessary to introduce hydraulic equipment, resulting in increased costs.

  The present invention has been made paying attention to such points, and the same one rod type steering cylinder is used without complicating the steering hydraulic circuit and without introducing new hydraulic equipment. An object of the present invention is to provide an all-hydraulic power steering device that can be expanded and contracted with characteristics.

  An all-hydraulic power steering apparatus according to the present invention connects one oil chamber of a single rod type steering cylinder to one of a pair of ports provided in a metering pump, and connects the other oil metering pump to the other of the metering pump. The port and one secondary port of the control valve linked to the steering handle are connected in communication, and the other oil chamber of the steering cylinder and the other secondary port of the control valve are connected in communication. It is characterized by.

  According to the above configuration, for example, as shown in FIG. 1, the bottom side oil chamber 2 b of the steering cylinder 1 is connected to one port 4 b of the metering pump 4 and the other port 4 a of the metering pump 4 is connected. Is connected to one secondary port 3a of the control valve 3 and the oil chamber 2a on the rod side of the steering cylinder 1 and the other secondary port 3a of the control valve 3 are connected to each other. In both the shortening operation and the extension operation, the amount of oil supplied to and discharged from the bottom oil chamber 2b is measured, so that the left and right steering characteristics are the same.

  Therefore, according to the present invention, an all-hydraulic power that can extend and retract a single rod type steering cylinder with the same characteristics without complicating the steering hydraulic circuit and without introducing new hydraulic equipment. A steering device can be configured.

  FIG. 1 shows a hydraulic circuit diagram of a fully hydraulic power steering apparatus according to the present invention. This all-hydraulic power steering device is mainly mounted on a four-wheel drive type work vehicle such as a tractor or a mower, and is a steering cylinder that drives and steers steering wheels (not shown) (mainly front wheels). 1 is a single rod type in which a piston rod 1a protrudes only on one side, and oil chambers 2a and 2b formed on both sides of the piston 1b include a control valve 3 and a metering pump 4. Are connected to the output ports 5a and 5b of the control unit 5 via pipes 6a and 6b such as pressure-resistant hoses.

  The output port 5a connected to the rod-side oil chamber 2a in the steering cylinder 1 is connected to one secondary port 3a of the control valve 3 via the oil passage a and also connected to the bottom-side oil chamber 2b. The connected output port 5b communicates with one port 4b of the metering pump 4 via an oil passage b, and the other port 4a of the metering pump 4 is connected to the other secondary port 3b of the control valve 3. It communicates via an oil passage c. That is, the steering cylinder 1, the control valve 3, and the metering pump 4 are connected in series.

  According to the above configuration, for example, when the steering handle 7 is rotated in the direction in which pressure oil is supplied to the oil passage a and the steering cylinder 1 is shortened, the metering pump is discharged from the bottom oil chamber 2b. 4 is measured by the metering pump 4, and the steering handle 7 is reversely rotated in the direction in which the pressure oil is sent out from the oil passage b, so that the steering cylinder 1 is extended. When operating, the amount of oil delivered from the oil passage b and supplied to the bottom oil chamber 2b is measured by the metering pump 4, and the bottom of the steering cylinder 1 is shortened and extended. By measuring the amount of oil supplied to and discharged from the side oil chamber 2b, the left and right steering characteristics are the same.

  In addition, as shown in FIG. 2, this invention can also be implemented by comprising a hydraulic circuit so that the metering pump 4 may measure the amount of oil entering and exiting the rod-side oil chamber 2a.

Hydraulic circuit diagram of fully hydraulic power steering system Hydraulic circuit diagram of another embodiment

Explanation of symbols

1 Steering cylinder 2a Oil chamber 2b Oil chamber 3 Control valve 3a Secondary port 3b Secondary port 4 Metering pump 4a Port 4b Port 7 Steering handle

Claims (1)

  One oil chamber of a single rod type steering cylinder is connected to one of a pair of ports provided in the metering pump, and one of control valves linked to the other port of the metering pump and a steering handle. And a secondary oil port of the steering cylinder and the other secondary port of the control valve are connected in communication with each other.

Images