JPH06249155A - Gear pump - Google Patents

Abstract

PURPOSE:To eliminate waste consumption of energy in adjustment of pump delivery pressure. CONSTITUTION:Pump chambers P of which volume increases or decreases periodically by the movement made according to the rotation of an internal gear body 1 rotated drivingly and an external gear body 2 rotated in engagement with the internal gear body 1 are formed between these gear bodies 1 and 2. A fluid sucked from a suction port 31 to the pump chambers P is delivered under compression to a delivery port 32. The internal gear body 1 is divided into an inner ring body 11 which is connected directly to a rotating shaft for rotation and an outer ring body 12 which is located on the outside of the inner ring body 11 and around which teeth are formed. Also frictional members 4 comprising curved spring plate members are provided around the outer periphery of the inner ring body 11, and their top surfaces are made in contact at a specified frictional force with the bottom surface of grooves 17 formed all around the inner periphery of the outer ring body 12. Then pressure leading holes 13 are formed in the side walls of the grooves 17, and pump delivery pressure is led into the grooves to force the frictional members 4 inward at a delivery pressure over a specified limit for movement.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gear pump, and more particularly to a structure for adjusting its discharge pressure.

[0002]

2. Description of the Related Art Gear pumps are widely used as vehicle-mounted pumps because they are simple in structure, compact, and inexpensive. In such a gear pump,
A relief valve is provided in order to avoid an excessive increase in pump discharge pressure when the load fluctuation is large or when the pump rotational speed is widely changed due to being connected to the engine (for example, Japanese Patent Laid-Open No. 3-237281). issue).

[0003]

However, in the pressure adjustment by the relief valve, excess energy that is not supplied to the load and bypassed through the relief valve causes a pressure loss, so that pump energy is wasted during the pressure adjustment. , Causing deterioration of engine fuel consumption.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a gear pump that does not waste energy consumption when adjusting the pump discharge pressure.

[0005]

The structure of the present invention will be described. Between the inner gear body 1 which is rotationally driven and the outer gear body 2 which is meshed with the inner gear body 1 and is rotated, these gear bodies 1,
In the gear pump which forms a pump chamber P that moves in accordance with the rotation of 2 and periodically expands or contracts its capacity, and compresses and discharges the fluid sucked from the suction port 31 into the pump chamber P to the discharge port 32. The gear body 1 is divided into an inner ring body 11 which is directly coupled to a rotating shaft and rotates, and an outer ring body 12 which is located outside of the inner ring body 11 and has a tooth profile on the outer periphery thereof. In addition, a friction member 4 having a spring property and protruding outwardly so that the tip 4b contacts the inner circumference of the outer ring body 12 with a predetermined friction force is provided, and the pump discharge pressure is applied to the pressure receiving surface 4a formed on the friction member 4. Introduce,
A pressure introducing passage 13 for pressing and moving the friction member 4 inward with a discharge pressure of a predetermined value or more is provided.

[0006]

In the above structure, when the pump discharge pressure does not reach the predetermined upper limit value, the friction member 4 contacts the inner circumference of the outer ring body 12 with a predetermined frictional force, and the inner ring body 11 is attached to the outer ring body 12. Is transmitted to supply and discharge the fluid.

When the pump discharge pressure reaches an upper limit value of a predetermined value or more, the friction member 4 is pressed and moved inward, its tip is separated from the inner circumference of the outer ring body 12, and the inner ring body 11 is moved.
And the outer ring body 12 are separated. As a result, the rotational force of the inner ring body 11 is not transmitted to the outer ring body 12, the rotation of the outer ring body 12 is stopped, the pump discharge is stopped, and the rise of discharge pressure is prevented.

Thus, no excess fluid is discharged when adjusting the pump discharge pressure, so that no wasteful energy is consumed.

[0009]

FIG. 1 shows the overall structure of a gear pump. In the drawing, an inner gear body 1 and an outer gear body 2 are housed in a circular space of a housing 3, and the outer gear body 2 has a circular outer circumference slidably contacting an inner circumference of the housing 3. A large number of trochoidal tooth profiles are formed on the inner peripheral surface of the outer gear body 2, and an inner gear body 1 having a small diameter is arranged in the gear body 2 in an eccentric state, and the tooth profile formed on the outer periphery of the inner gear body 1 is an outer gear. It meshes with the tooth profile of body 2.

Therefore, a large number of pump chambers P are formed between these tooth profiles, and the volume of these pump chambers P periodically increases or decreases as the gear bodies 1 and 2 rotate. On the side wall of the housing 3, a suction port 31 is formed in a substantially half circumference facing the pump chamber P that gradually expands as the gear bodies 1 and 2 rotate counterclockwise, and faces the pump chamber P that gradually shrinks. A discharge port 32 is formed on the half circumference.

The inner gear body 1 is divided into an inner ring and an outer ring, and is composed of an outer ring body 12 having a tooth profile on the outer circumference, and an inner ring body 11 located in contact with the inner circumference.
The inner ring body 11 is rotationally driven by being connected to a rotation shaft (not shown) by a spline 14 formed on the inner circumference.

Between the inner ring body 11 and the outer ring body 12, four friction members 4 are arranged at equal intervals in the circumferential direction to connect them. The details will be described with reference to FIG. 2.
In some places, the center of the peripheral surface is deleted to have an arc cross section to form a recess 15, and the friction member 4 is disposed in the recess 15.

The friction member 4 is formed by curving a rectangular spring plate into an arc shape, and both ends thereof are joined to both end edges of the recess 15, and the top surface 4b thereof is an inner ring body as shown in FIG. It projects outward from the outer peripheral surface of 11. Recess 1
A drain hole 16 penetrating to the inner periphery is provided at the center of the bottom surface of the friction member 5, and a low pressure drain pressure is introduced behind the friction member 4.

As shown in FIG. 2, on the inner peripheral surface of the outer ring body 12, a rectangular groove 17 having the same width as the recess 15 is formed at the center of the peripheral surface, and the friction member 4 projects. The top surface 4b enters the groove 17 and is pressed against the groove bottom surface by a predetermined frictional force by its own spring force.

A large number of pressure introducing holes 13 are formed in the side wall of the rectangular groove 17 at equal intervals in the circumferential direction, and these pressure introducing holes 13 are formed when passing over the discharge port 32. In communication with each other, the pump discharge pressure is introduced into the groove.

However, the surface of the friction member 4 except the top surface 4b becomes the pressure receiving surface 4a (FIG. 3) and receives the pump discharge pressure,
The back side receives drain pressure.

When the load is low, the pump discharge pressure is in the normal range where it does not reach the upper limit value. Therefore, each friction member 4 resists the discharge pressure introduced from the pressure introducing hole 13 and, by its own spring force, has a predetermined value. It is in contact with the groove bottom surface of the outer ring body 12 by frictional force. As a result, the rotational force of the inner ring body 11 is transmitted to the outer ring body 12 and the two rotate integrally, and the pump chamber P rotates and moves to suck and discharge the fluid.

When the pump discharge pressure increases and reaches the upper limit value under high load, the differential pressure between the discharge pressure and the drain pressure increases, and the friction member 4 receives the pressing force and is deformed into the recess 15. . The top surface 4b of the friction member 4 is separated from the bottom surface of the groove of the outer ring body 12, the rotational force of the inner ring body 11 is not transmitted, and the rotation of the outer ring body 12 is stopped. As a result, the discharge of the fluid is stopped, and the pump discharge pressure is prevented from rising above the upper limit value.

[0019]

As described above, according to the gear pump of the present invention, when the discharge pressure exceeds the upper limit value, the rotation of the pump is substantially stopped and the fluid discharge is stopped, so that pump energy is wasted. It is possible to prevent the pump discharge pressure from rising excessively without being consumed.

[Brief description of drawings]

FIG. 1 is a front view of the inside of a pump showing an embodiment of the present invention.

FIG. 2 is an enlarged exploded perspective view of a main part of the pump.

FIG. 3 is an enlarged side view of a main part of a pump.

[Explanation of symbols]

 1 Inner gear body 11 Inner ring body 12 Outer ring body 13 Pressure introduction hole (pressure introduction path) 2 Outer gear body 3 Housing 31 Suction port 32 Discharge port 4 Friction member 4a Pressure receiving surface 4b Top surface (tip) P Pump chamber

Claims (1)

[Claims] 1. A pump chamber between an inner gear body that is rotationally driven and an outer gear body that is meshed with the inner gear body and is rotated by the rotation of these gear bodies to cyclically expand or reduce the capacity. In the gear pump that forms the above, and compresses and discharges the fluid sucked into the pump chamber from the suction port to the discharge port, the inner gear body is directly connected to the rotation shaft and is rotated to the inner ring body and positioned outside the inner ring body. The outer ring body is divided into outer ring bodies having a tooth profile on the outer circumference, and the outer ring body has a spring member that projects outward and has a tip contacting the inner circumference of the outer ring body with a predetermined friction force. And a pressure introducing passage for introducing a pump discharge pressure onto the pressure receiving surface formed on the friction member and for moving the friction member inward at a discharge pressure of a predetermined value or more. .