JP2016075201A - Hydraulic motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic motor capable of preventing the breakage of an oil seal by avoiding a pressure rise of leak oil in a casing.SOLUTION: A hydraulic motor includes: a casing; a supply port and a discharge port; a rotation power generating mechanism portion; a drain passage; and a make-up passage. A leak oil collecting portion is provided in the inside of the casing. The collecting portion and the make-up passage are connected by a communication path. The communication path is provided with communication control means which normally intercepts a flow of the oil from the make-up passage to the collecting portion, and permits the flow of the oil from the collecting portion to the make-up passage when the pressure of the leak oil in the casing is a predetermined value or more.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to a hydraulic motor.

  For example, a hydraulic motor such as a swash plate type piston motor is generally used as a revolving body drive motor for a construction machine such as a hydraulic excavator. In this type of hydraulic motor, a rotational power generation mechanism that provides rotational power to the motor shaft by supplying and discharging pressure oil is provided in the casing of the motor. The motor casing is provided with a drain passage for returning leak oil generated inside the casing to an external tank and a makeup passage connected to a hydraulic circuit for suppressing cavitation.

  The hydraulic circuit that suppresses cavitation is a circuit that prevents cavitation that occurs when the hydraulic motor rotates beyond the amount of oil supplied from the hydraulic pump by the inertial force of the swing body during the swing stop operation.

  By the way, the leak oil inside the casing is returned from the drain passage to the tank, but when a filter is installed between the drain passage and the tank, if the filter is clogged, the leak oil inside the casing There was a possibility that the oil seal that prevented the leaked oil from leaking outside the casing would be damaged due to an increase in pressure.

Japanese Patent Laid-Open No. 2007-177764

  The problem to be solved by the present invention is to provide a hydraulic motor capable of preventing the oil seal from being damaged by avoiding an increase in the pressure of leaked oil in the casing.

  The hydraulic motor of the embodiment has a casing, a supply port and a discharge port, a rotational power generation mechanism, a drain passage, and a makeup passage. The casing rotatably supports the motor shaft. The supply port and the discharge port are provided in the casing. The rotational power generation mechanism is provided inside the casing and applies rotational power to the motor shaft by pressure oil supplied and discharged via the supply port and the discharge port. The drain passage is provided in the casing, and leak oil generated inside the casing is returned to the external tank. The makeup passage is provided in the casing and is connected to a hydraulic circuit that suppresses cavitation. And the reservoir part of leak oil is provided in the inside of a casing. The pool portion and the makeup passage are connected by a communication passage. Communication control that always shuts off the oil flow from the makeup passage to the reservoir in the communication passage, and allows the oil flow from the reservoir to the makeup passage when the pressure of the leaked oil inside the casing exceeds a predetermined level. Means are provided.

A circuit diagram showing a hydraulic motor of an embodiment. The schematic block diagram which shows the hydraulic motor of embodiment.

  Hereinafter, a hydraulic motor according to an embodiment will be described with reference to the drawings.

  FIG. 1 is a circuit diagram of a hydraulic motor, and FIG. 2 is a schematic configuration diagram of the hydraulic motor. The hydraulic motor of this embodiment is, for example, a swash plate type piston motor that drives to rotate an upper swing body (not shown) of a hydraulic excavator.

  As shown in FIGS. 1 and 2, the swash plate type piston motor 1 has a casing 2. The casing 2 includes a front casing 2A that is formed in a cylindrical shape with the rear end (upper end in FIG. 2) opened, and a rear casing 2B that closes the rear end opening of the front casing 2A. Inside the casing 2, a swash plate 5, a plurality of pistons 10, a cylinder block 20, a valve plate (valve plate) 30, a motor shaft 3, a mechanical brake mechanism 40, and the like are provided.

  The front surface (lower surface in FIG. 2) of the swash plate 5 is fixed to the inner surface of the front casing 2A by bolts or the like, and the shoe 6 is attached to the rear surface (upper surface in FIG. 2) of the swash plate 5. It is slidably contacted. Each piston 10 has a spherical head 12 at the front end, and is engaged with the shoe 6 through the spherical head 12 so as to be swingable.

  The cylinder block 20 is formed in a columnar shape and is accommodated in the front casing 2A. A plurality of cylinder chambers 22 are formed in the cylinder block 20 to hold the piston 10 slidably. The plurality of cylinder chambers 22 are formed around the rotation axis of the cylinder block 20 at equal intervals in the circumferential direction, and each is configured as a working chamber to which pressure oil for operation is supplied.

  The valve plate 30 is formed in an annular shape, and is disposed between the rear end of the cylinder block 20 and the front end of the rear casing 2B. The valve plate 30 is provided with a crescent-shaped pressure oil supply / discharge port 32 for supplying and discharging pressure oil to and from the cylinder chamber 22 of the cylinder block 20.

  The motor shaft 3 has a retainer portion 4 at the rear end, and is coaxially integrated with the front end of the cylinder block 20 via the retainer portion 4. A ring-shaped leaf spring 8 that presses the shoe 6 against the swash plate 5 is attached to the retainer portion 4 via a return plate 7. The motor shaft 3 has a front end that is an output end that passes through the center hole of the swash plate 5 and projects outside the front casing 2A. The motor shaft 3 is rotatably supported by a tapered roller bearing 51 via an oil seal 55 on a boss portion 9 formed at the front end portion of the front casing 2A at a position slightly rearward of the protruding front end. Yes.

  The rear casing 2B is fixed to the front casing 2A with bolts 58 and the like. The rear casing 2B is provided with an A port and a B port for supplying and discharging pressure oil to and from a pressure oil supply / discharge port 32 of the valve plate 30 (see FIG. 1). These A port and B port are two pressure oil supply / discharge ports, one of which serves as a pressure oil supply port into the motor and the other of which serves as a pressure oil discharge port from the motor.

  A swash plate 5, piston 10, cylinder block 20, and valve plate 30 are mainly used to constitute a rotational power generation mechanism 90 that applies rotational power to the motor shaft 3. That is, the pressure oil is supplied to the cylinder chamber 22 through the supply port (A port or B port). Further, the pressure oil is discharged from the cylinder chamber 22 through the discharge port (B port or A port). The operating force acting on the flow of the pressure oil acts on the rotational power generation mechanism section 90, and the rotational power generation mechanism section 90 imparts rotational power to the motor shaft 3.

Further, the casing 2 has a makeup passage connected to a drain passage 60 and a drain port Dr for returning leakage oil generated in the casing 2 to the external tank T, and a hydraulic circuit 110 (see FIG. 1) for suppressing cavitation. 70 and a makeup port Mu are provided. The drain port Dr and the makeup port Mu are open to the rear casing 2B.
As shown in FIG. 1, the drain port Dr is connected to the tank T via the filter 102. The makeup port Mu is connected to the tank T via the makeup line L3 in the middle of the return line L2.

  A recess 24 is provided at the center of the rear end surface of the cylinder block 20, and a protrusion 26 protruding from the center of the front end surface of the rear casing 2 </ b> B is provided in the recess 24 via a needle bearing 52. It is fitted freely.

  A leak oil reservoir 80 is secured inside the casing 2 by a gap between the recess 24 and the protrusion 26. The pool portion 80 is connected to the makeup passage 70 by a communication passage 82 formed inside the rear casing 2B. The communication passage 82 is provided with a check valve 84 as communication control means.

  This check valve 84 always shuts off the flow of oil from the makeup passage 70 side to the reservoir 80 side, and when the pressure of the leaked oil inside the casing 2 is equal to or higher than a predetermined value, the check valve 84 moves from the reservoir 80 to the makeup passage 70. It functions to allow the flow of oil. In other words, the check valve 84 prevents the back flow from the makeup passage 70 side to the accumulation portion 80 side, and quickly increases the pressure of the leak oil to a predetermined pressure, and when the pressure exceeds the predetermined pressure, the check valve 84 increases the pressure of the leak oil. It is designed to perform the function of escaping.

  The mechanical brake mechanism 40 generates a braking force against the cylinder block 20 by friction engagement between the friction plate 42 on the cylinder block 20 side and the friction plate 43 on the casing 2 side by the biasing force of the spring 41. On the other hand, the brake force is released by the movement of the brake piston 44 against the urging force of the spring 41.

As shown in FIG. 1, the hydraulic circuit 110 for suppressing cavitation includes a pair of relief valves RF1 and RF2 and a pair of check valves CH1 and CH2, and communicates with a makeup port Mu and a makeup passage 70.
In FIG. 1, GA and GB are ports for connecting a pressure gauge. The hydraulic circuit 110 for suppressing cavitation can be formed outside the casing 2, but is formed inside the casing 2 in the present embodiment.

The A port and B port of the swash plate type piston motor 1 are connected to the control valve unit 150 via the supply / discharge line L1. A hydraulic pressure supply source 160 such as a hydraulic pump is connected to the control valve unit 150, and a return line L2 for returning the return oil from the swash plate type piston motor 1 to the tank T is connected.
The return line L2 is a line that returns the oil to the tank T via the check valve 120. The makeup port Mu is connected to the upstream side of the check valve 120 in the return line L2. The pressure of makeup port Mu is set by the spring force of check valve 120 so as to provide a function of suppressing cavitation, and is usually a low pressure of about 0.3 MPa.

Next, the operation of the swash plate type piston motor 1 will be described.
When pressure oil is supplied from the A port or B port to the cylinder chamber 22 of the cylinder block 20 via the pressure oil supply / discharge port 32 of the valve plate 30, the piston 10 is moved by the pressure oil supplied to the cylinder chamber 22. It moves in the direction pushed out from the cylinder chamber 22. Accordingly, when the shoe 6 is pressed against the swash plate 5, the reaction force at that time acts on the cylinder block 20 as a component force in the rotational direction via the piston 10, so that the cylinder block 20 and the motor shaft 3 rotate. start. From the cylinder chamber 22 where the piston 10 exceeds the top dead center, the pressure oil is discharged to the A port or the B port through the pressure oil supply / discharge port 32 of the valve plate 30 and returned to the tank T.

  When operating in this way, leak oil is generated in the casing 2. The leaked oil is supplied to the following lubrication and the like, then passes through the drain passage 60 and the drain port Dr, and is returned to the tank T through the filter 102. That is, the leak oil lubricates the sliding surfaces of the piston 10 and the cylinder block 20, lubricates the sliding surfaces of the swash plate 5 and the shoe 6, lubricates the rolling surfaces of the needle bearing 52 and the tapered roller bearing 51, and the valve plate 30. It is used for lubrication of the sliding surface between the cylinder blocks 20, lubrication between the friction plates 42 and 43 of the mechanical brake mechanism 40, and the like.

  In the unlikely event that the filter 102 is clogged and the pressure of the leak oil cannot be released from the drain passage 60 and the drain port Dr, the leak oil reservoir 80 is connected to the makeup passage 70 via the communication passage 82. Therefore, the pressure of the leaked oil can be released to the makeup passage 70 through the route.

At that time, the flow of oil from the makeup passage 70 side to the reservoir 80 side is always blocked in the communication passage 82, and when the pressure of the leaked oil inside the casing 2 is equal to or higher than a predetermined value, the makeup passage 80 Since the check valve 84 that allows the oil flow to the passage 70 is provided, the pressure of the leaked oil can be quickly increased to a predetermined pressure in normal times.
Further, even if the makeup passage 70 becomes high pressure, an increase in pressure inside the casing 2 can be avoided. For this reason, it is possible to prevent damage to the oil seal 55 that prevents oil leakage to the outside.

  In the above-described embodiment, the check valve 84 is taken as an example of the communication control means, but a relief valve may be used instead of the check valve, or a pressure regulator may be used.

According to at least one embodiment described above, the leak oil reservoir 80 inside the casing 2 is connected to the makeup passage 70 via the communication control means (check valve 84), and therefore via the drain port Dr. Even when the filter 102 in the line for returning the leaked oil to the tank T is clogged, an increase in the pressure of the leaked oil in the casing 2 can be safely avoided.
Further, due to the function of the communication control means, it is possible to safely avoid the increase in the pressure of the leaked oil in the casing 2 even if the pressure in the makeup passage should increase. Therefore, the oil seal 55 can be effectively prevented from being damaged.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 1 ... Swash plate type piston motor (hydraulic motor), 2 ... Casing, 2A ... Front casing, 2B ... Rear casing, 3 ... Motor shaft, 5 ... Swash plate, 10 ... Piston, 20 ... Cylinder block, 22 ... Cylinder chamber ( Working chamber), 24 ... concave portion, 26 ... convex portion, 30 ... valve plate, 90 ... rotational power generation mechanism portion, 60 ... drain passage, 70 ... make-up passage, 80 ... reservoir portion, 82 ... communication passage, 84 ... check Valve (communication control means), 102 ... filter, 110 ... hydraulic circuit for suppressing cavitation, A ... A port (supply port, discharge port), B ... B port (supply port, discharge port), Dr ... drain port, T …tank

Claims (3)

A casing that rotatably supports the motor shaft;
A pressure oil supply port and a discharge port provided in the casing;
A rotational power generating mechanism that provides rotational power to the motor shaft by pressure oil provided inside the casing and supplied and discharged via the supply port and the discharge port;
A drain passage provided in the casing for returning leaked oil generated inside the casing to an external tank;
A makeup passage provided in the casing and connected to a hydraulic circuit for suppressing cavitation;
In a hydraulic motor comprising:
A reservoir of the leaked oil is provided inside the casing;
The reservoir and the makeup passage are connected by a communication passage,
An oil flow from the make-up passage to the reservoir is constantly blocked in the communication passage, and the oil from the reservoir to the make-up passage when the pressure of the leaked oil inside the casing is equal to or higher than a predetermined value. A hydraulic motor provided with a communication control means for allowing the flow of air.   The hydraulic motor according to claim 1, wherein one of a check valve, a relief valve, and a pressure regulator is provided as the communication control means. The casing is composed of a front casing formed in a cylindrical shape with the rear end opened, and a rear casing that closes the rear end opening of the front casing,
The rotational power generation mechanism is
A swash plate provided in the front casing;
A plurality of pistons slidably engaged with the swash plate via shoes;
A cylinder block provided in the front casing and having a plurality of cylinder chambers for slidably holding the plurality of pistons, and the motor shaft being integrally formed on the front end side;
An annular valve plate provided between the cylinder block and the rear casing;
Have
A concave portion is provided on the rear end surface of the cylinder block, and a convex portion protruding from the front end surface of the rear casing is fitted into the concave portion via a bearing,
The reservoir of the leaked oil is formed by a gap between the concave portion and the convex portion,
The hydraulic motor according to claim 1, wherein the communication passage is formed in the rear casing.

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