JPH05240166A - Internal gear pump - Google Patents

Abstract

PURPOSE:To suppress an increase in discharge quantity and required power accompanying a rise of rotating speed in an internal gear pump. CONSTITUTION:A discharge port is divided to a front discharge port 8 forward in rotating direction and a rear discharge port 9 backward in rotating direction. The rear discharge port 9 is connected to a discharge passage 10, and a connecting passage 12 for connecting the front discharge port 9 to the discharge passage 10 is provided. The inlet passage 14 to the inlet port 7 has a throttle 15 and a bypass passage 16 bypassing this. The connecting passage 12 and the bypass passage 16 have control valves 11, 17 for continuing them in low rotating speed state and closing them in high rotating speed state, respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is driven by a drive source whose rotational speed fluctuates greatly, such as an automobile engine, and increases the discharge amount accordingly even if the rotational speed rises above a certain value. The present invention relates to an internal gear pump capable of suppressing the increase in power required to drive the pump.

[0002]

2. Description of the Related Art Such an internal gear pump is disclosed in Japanese Patent Publication No. 46-14946. That is, the discharge ports provided in the volume reduction area of the pump working chamber formed between the internal teeth, the external teeth, and the tooth grooves of the internal and external gears that mesh with each other are divided into the front and the rear in the rotational direction, respectively. The discharge port on the rear side in the rotation direction is always connected to the discharge passage, and the discharge port on the front side in the rotation direction is connected to the discharge passage when the rotation speed is low, so that the rotation speed increases and the pressure in the discharge passage increases. When it becomes larger than a predetermined value, the connection destination is changed by a valve from the discharge passage to the tank, so that the pump action of the pump working chamber in the range leading to the discharge port on the front side in the rotation direction becomes the unload state, The increase in the discharge amount and the increase in the power required to drive the pump are suppressed.

[0003]

However, in such a structure, even after the discharge port on the front side in the rotation direction is connected to the tank, the discharge amount obtained from the discharge port on the rear side in the rotation direction increases as the rotation speed increases. Therefore, in a high-speed state in which the rotation speed is further increased, there is a problem that the ejection amount becomes much larger than the required amount. The present invention solves such a problem and provides an internal gear pump in which the discharge amount hardly changes even when the rotation speed rises above a certain value without being affected by this. is there.

[0004]

For this reason, in the internal gear pump of the present invention, the discharge port is divided into a front discharge port on the front side in the rotational direction and a rear discharge port on the rear side in the rotational direction, and these both discharge ports are divided. The pump working chamber is provided so as to be spaced in the direction of rotation so as not to be communicated by the pump working chamber, and the discharge passage is connected to the rear discharge port and the connection passage for connecting the front discharge port to the discharge passage is provided. A throttle valve is provided in the suction passage to be connected and a bypass circuit is provided to bypass this throttle valve, and a control valve that connects the connection passage and the bypass circuit at a low rotation speed and closes at a high rotation speed is installed. ..

[0005]

According to the internal gear pump of the present invention constructed as described above, at a low rotational speed at which the bypass and the connection passage are brought into conduction by the control valve, the suction passage is throttled from the suction port to the pump working chamber. The liquid that has passed through the bypass is supplied, is discharged to the front discharge port and the rear discharge port, and is sent to the use unit via the discharge passage. Then, as the number of rotations increases, the control valve closes the bypass and the connection passage so that the liquid to the suction port is throttled without passing through the bypass and the liquid to the discharge passage is discharged to the rear discharge port. Only discharged from. In this state, the liquid sent from the suction passage to the suction port is subject to the resistance due to the throttle, so that the good suction property cannot be radiated, and the pump working chamber passing through the suction port is partially filled with the liquid. It moves to the volume reduction area without being filled and reaches the front discharge port while reducing the volume. At this time, the pump working chamber is only partially filled with liquid, and the front discharge port is not communicated with the rear discharge port via the preceding pump working chamber, and the connection passage is closed. Therefore, the discharge liquid is prevented from flowing back to the front discharge port and instantaneously filling the pump working chamber reaching the front discharge port, so that the volume reduction of the pump working chamber simply means that the volume of the non-liquid portion is reduced. No more discharging, no more power is consumed for discharging. Then, the pump working chamber moves while further reducing the volume thereof, and after the non-liquid portion thereof disappears or becomes sufficiently small, the pump working chamber reaches the post discharge port, and the discharge action is performed. On the other hand, when the bypass is closed, resistance is imparted by the restriction of the suction passage, and as a result, cavitation is generated downstream of the restriction and bubbles are generated accordingly. The air bubbles further hinder the inhalation of liquid, and as the number of revolutions increases, the cavitation and the accompanying foaming action become more significant, so the air bubbles further obstruct the inhalation and close the bypass. After that, even if the rotation speed increases, the flow rate of the liquid supplied to the suction port hardly increases and becomes almost constant. As a result, the discharge amount discharged from the post discharge port is almost constant regardless of the rotation speed. Becomes

[0006]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1 showing the first embodiment, reference numeral 1 is a casing, and a ring-shaped internal gear 3 is provided in a concave hole 2 thereof, and an external gear 4 is rotatably eccentrically provided in the internal gear 3. It is housed. Incidentally, here, a lid member is further provided so as to close the opening side of the concave hole 2 so as to cover the casing 1 and both gears 3, 4, but this is not shown in the drawing. Each gear 3,
4 has a plurality of inner teeth 3a and outer teeth 4a.
a and the outer teeth 4a mesh with each other, so that the meshing portions A, A
The plurality of pump working chambers 5 separated in the circumferential direction by the inner teeth 3
It is formed between a, the outer tooth 4a, and these tooth grooves 3b, 4b.

A drive shaft 6 is connected to the external gear 4 and is rotated counterclockwise in the illustrated state. Reference numeral 7 denotes a suction port, which is a region where the volume of the pump operating chamber 5 increases when the gears 3 and 4 are rotated by the drive shaft 6, that is, in the left side of the line connecting the centers of the gears 3 and 4 in the illustrated state. Room 5
As is well known, the bottom wall of the concave hole 2 is provided so as to be able to communicate with. 8 and 9 are the front discharge port and the rear discharge port,
In the volume reduction area of the pump operating chamber, that is, on the right side of the line connecting the centers of the gears 3 and 4 in the illustrated state, the bottom wall of the recessed hole 2 is provided so as to be able to communicate with the pump operating chamber 5.

Here, the front discharge port 8 which is the front in the rotational direction and the rear discharge port 9 which is the rear in the rotational direction are such that the pump working chamber 5 that moves with rotation has the rear end side of the front discharge port 8. And the discharge ports 8 and 9 are not connected to each other at the same time by the front end side of the rear discharge port 9 and the discharge ports 8 and 9 are communicated with each other through the pump working chamber 5. 10
In the discharge passage to which the rear discharge port 9 is connected, the front discharge port 8 to the discharge passage 10 are provided with a connection passage 12 in which a 2-port normally open solenoid valve 11 serving as a control valve is installed.

A throttle 15 is installed in the suction passage 14 connecting the suction port 7 and the tank 13, and a bypass 16 bypassing the throttle 15 is used as a control valve for a 2-port normally open solenoid valve. 17 is installed and provided. Also,
Reference numeral 18 detects the number of revolutions of the drive shaft 6, and when it is below a predetermined value, each solenoid valve 11, 17 is kept open, and when it is above a predetermined value, the solenoid valves 11, 16 are opened and closed to close each solenoid valve 11, 17. It is an operating device for. Reference numeral 19 denotes a use portion of the discharged liquid connected to the discharge passage 10, 20 is a return passage for returning the liquid from the use portion 19 to the tank 13, and 21 is a relief valve.

Next, the operation of the first embodiment will be described.
Now, when the drive shaft 6 is rotated and the number of rotations thereof is equal to or lower than a predetermined value, the solenoid valves 11 and 17 are open, and the connection path 12 and the detour 16 are kept conductive. In this state, the suction of the liquid is not affected by the throttle 15 by the bypass 16, and the good suction property is radiated, and the pump working chamber 5 passing through the suction port 7 in the volume increasing region is filled with the liquid. The volume of the pump working chamber 5 is discharged from the front discharge port 8 and the rear discharge port 9 in accordance with the decrease in the volume. Here, if the interval in the rotation direction between the discharge ports 8 and 9 is made extremely large with respect to the length of the pump operation chamber 5 in the rotation direction, the pump operation chamber 5 closed between the discharge ports 8 and 9 will be described. Although the liquid leaks from the sliding gap between the internal gear 3 and the external gear 4, a situation occurs in which the liquid is excessively compressed and becomes extremely high pressure, resulting in a wasteful power loss. To select the space between both discharge ports so as not to copy,
This can be appropriately performed by an experiment or the like while considering the sliding gap of 4 and the like.

When the rotation speed increases, the suction amount and the discharge amount increase accordingly. When the rotation speed reaches a predetermined value, the solenoid valves 11, 17 are operated by the operating device 18.
Is closed, and the connection path 12 and the detour 16 are closed. In this state, the suction of the liquid is hindered by the action of the throttle 15, and the pump working chamber 5 passing through the volume increasing region is not sufficiently supplied with the liquid from the suction port 7 and the volume thereof is partially filled with the liquid. Move to the reduction zone. Then, the pump working chamber 5 passes through the front discharge port 8 while reducing its volume, but the front discharge port 8 has the connection passage 12 closed, and communicates with the rear discharge port 9 by the preceding pump working chamber 5. Since the discharge liquid does not flow back to the front discharge port 8 and fills the pump working chamber 5 passing therethrough instantly, the situation of the pump working chamber 5 passing through the front discharge port 8 is prevented. The volume reduction is merely a reduction in the volume of the non-liquid portion, no ejection action is performed, and no power for ejection is consumed.

Then, the pump working chamber 5 reaches the post discharge port 9 in a state where the non-liquid portion thereof disappears or becomes sufficiently small due to the volume reduction, and the discharge action to the post discharge port 9 is performed. On the other hand, the liquid sucked into the suction port 7 is given a resistance by the throttle 15 of the suction passage 14, as a result of which the suction property deteriorates, and cavitation occurs on the downstream side of the throttle 15, and along with this, bubbles are generated. Occurs. The suction of the liquid is again hindered by the air bubbles, and further, the cavitation and the foaming action accompanying it become remarkable as the number of revolutions increases. As a result of the air bubbles being hindered, the bypass 16 is closed. However, even if the number of rotations increases, the amount of liquid sucked in is substantially constant and becomes substantially constant. As a result, the amount of liquid discharged from the rear discharge port 9 also becomes substantially constant, so that the number of rotations is further increased. Even in the extremely high speed state in which the liquid is further raised, it is possible to prevent a situation in which the discharge amount of the liquid becomes much larger than the necessary amount at the use place 19. As a result, from the discharge passage 10 to the tank 13
Relief valve 2 installed to discharge the excess flow to the
1 can be downsized to a smaller capacity, and the relief valve 21
The relief valve 21 can be
It is possible to reduce the wasteful power loss due to the pressure override of.

Further, even if the number of rotations is increased in this way, the suction amount and the discharge amount of the liquid passing through the pump are substantially constant, so that the degree of shearing that the liquid used receives by passing through the pump is small. The life of the liquid used can be improved. Therefore, it is suitable for a case where compactness is required and a large amount of liquid to be used is not held in the tank, such as a pump for power steering of a vehicle or an automatic transmission.

2 to 4 show second to fourth embodiments, respectively. In addition, in FIGS. 2 to 4, in FIG.
Use point 19, return passage 20 and relief valve 21 in
However, these are connected and installed in the same manner as in the case of FIG. The difference from the case of the first embodiment of FIG. 1 will be described below. In the second embodiment of FIG. 2, the control valve is a single 4-port 2-position electromagnetic switching valve 22, which is operated by the operating device 18, respectively. The connection path 12 and the detour 16 are electrically connected and closed.

In the third embodiment of FIG. 3, the control valve for connecting and closing the connecting path 12 and the bypass 16 is raised by the increase in the discharge amount as the number of revolutions increases. The normally open type pilot on-off valves 23 and 24 are pilot-operated by the pressure of the discharge passage 10 so as to be closed when the pressure of the discharge passage 10 reaches a set value regulated by the springs 23a and 24b. It is a thing.

In the fourth embodiment of FIG. 4, the control valve for closing the conduction of the connecting passage 12 is a check valve 25 which free-flows from the front discharge port 8 side to the discharge passage 10 side. .. Also, in each of the embodiments shown in FIGS. 2 to 4, it is possible to obtain the same effect as that of the first embodiment shown in FIG. It should be noted that the single control valve of the 4-port 2-position type as shown in FIG. 2 and the control valve provided in the detour of FIG.
It is also possible to carry out the switching operation by the pilot operation by the pressure of the discharge passage as in the above.

[0017]

As described above, according to the present invention, when the connecting passage and the bypass are closed even if the rotation speed is increased, the liquid sucked in receives a resistance due to the restriction of the suction passage, and cavitation caused by this Due to the bubbling effect of the liquid, the amount of liquid suction and the amount of liquid discharge can be made almost constant regardless of the increase in the number of revolutions. It can be prevented.
In addition, since the suction amount and the discharge amount, that is, the amount of the liquid passing through the pump is substantially constant regardless of the increase in the number of rotations, the degree of shearing of the liquid due to passing through the pump is reduced and It is possible to improve the life, and it is suitable when compactness is not required and a large amount of liquid is not retained in the tank, such as a pump for a power steering or an automatic transmission for an automobile.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part showing a first embodiment of the present invention with a partial hydraulic circuit diagram.

FIG. 2 is a sectional view of an essential part showing a second embodiment of the present invention with a partial hydraulic circuit diagram.

FIG. 3 is a cross-sectional view of an essential part showing a third embodiment of the present invention with a partial hydraulic circuit diagram.

FIG. 4 is a cross-sectional view of an essential part showing a fourth embodiment of the present invention with a partial hydraulic circuit diagram shown.

[Explanation of symbols]

 3 Internal tooth gear 4 External tooth gear 3a Internal tooth 4a External tooth 3b, 4b Tooth groove 5 Pump working chamber 7 Suction port 8 Front discharge port 9 Rear discharge port 10 Discharge passage 12 Connection passage 14 Suction passage 15 Throttle 11, 17, 22 , 23,24,25 control valve

Claims (1)

[Claims] 1. An internal tooth of an internal gear and an external tooth of an external gear eccentrically arranged in the internal gear are meshed with each other to be formed between the internal tooth, the external tooth and these tooth grooves. An internal gear pump in which a suction port is provided in a volume increase area and a discharge port is provided in a volume decrease area due to rotation of both gears in the pump working chamber, and the discharge port is in the rotation direction. It is divided into a rear side rear discharge port and these both discharge ports are provided in the rotational direction at intervals so that they are not communicated by the pump working chamber, and the discharge passage is connected to the rear discharge port and the front side. A connection path is provided to connect the discharge port to the discharge path, a throttle is provided to the suction path connected to the suction port, and a bypass circuit is provided to bypass this restriction. Control that closes at a high speed with conduction. Internal gear pump with control valve installed.