JP2003028055A - Fluid force-feed device and tank for storing fluid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluid force-feed device having a structure advantageous in integrating two pumps and thus their driving sources into one unit. SOLUTION: A fuel supply system of an internal combustion engine is provided with a pump unit 12 for force-feeding dimethyl ether as fuel. The unit 12 includes a first pump part P1 having a gear pump, a second pump part P2 having a piston pump arranged on a downstream of the first pump part P1, and a motor part M having an electric motor. Both of the pump parts P1, P2 share the motor part M as the driving source, and housings 21-24 of both of the pump parts P1, P2, and the motor part M are integrated to form the one unit 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluid pumping device used in a fuel supply system for an internal combustion engine using dimethyl ether as a fuel, and a fluid storage tank having the device.

[0002]

2. Description of the Related Art In this type of fluid pumping apparatus, in order to reliably pump dimethyl ether (hereinafter referred to as DME) from a tank to an internal combustion engine (more specifically, a fuel injection apparatus) without vaporizing it, It has been proposed to dispose a gear pump on the upstream side of the main piston pump. That is, in order to prevent the pressure of the DME from falling below the saturation pressure due to the expansion (suction) stroke of the piston pump, the DME is pressurized by the gear pump having no expansion stroke.

[0003]

However, in the conventional fuel supply system, the two pumps are independent of each other, and the electric motor as the drive source is also provided in each of them. Therefore, there has been a problem that the fuel supply system becomes large and expensive.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a fluid pumping device having a structure advantageous in that two pumps and even their driving sources are combined into one unit, and a fluid storage tank having the device. .

[0005]

In order to achieve the above object, the invention of claim 1 is a fluid pumping device used for pumping a fluid that becomes a gas at a saturation pressure or lower, and has no expansion stroke. It is composed of a first pump and a second pump having an expansion stroke in which the suction side is connected to the discharge side of the first pump, and the drive source of the first pump and the drive source of the second pump are made common. It is a characteristic fluid pumping device.

In this structure, since the fluid is pressurized by the first pump, it is possible to prevent the fluid from being vaporized in the expansion stroke of the second pump. Further, as compared with the case where a drive source for each pump is separately provided, the fluid pressure feeding device can be downsized and the configuration can be simplified, and the manufacturing cost can be reduced.

Further, the common use of the drive source for the first pump and the drive source for the second pump is advantageous in that both pumps, and thus the drive sources, are made into one unit. According to a second aspect of the present invention, in the first aspect, the drive source is an electric motor, and the housing of the electric motor, the housing of the first pump, and the housing of the second pump are integrated.

In this structure, both pumps and the electric motor are one unit. According to a third aspect of the present invention, in the first or second aspect, the drive shaft of the first pump and the drive shaft of the second pump are arranged on the same axis and are uniaxial.

In this structure, for example, when the first pump is operatively connected to the drive source and the second pump is operatively connected to the first pump, a complicated power transmission structure is formed between the two pumps. It is not necessary and the structure of the fluid pressure feeding device can be simplified.

The invention according to claim 4 is based on any one of claims 1 to 3, wherein an excessive pressure in the passage is connected to the communication passage connecting the discharge side of the first pump and the suction side of the second pump. It is characterized in that a relief valve that releases the gas to the upstream side of the first pump is also provided.

In this structure, the relief valve can prevent an excessive increase in pressure in the communication passage.
It is possible to prevent the power loss from increasing due to excessive pressurization of the pump.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the second pump is a piston pump,
A crank chamber for accommodating a cam body for converting the rotational movement of the drive shaft into the reciprocating movement of the piston is defined in the housing of the second pump.
It is characterized in that it is connected to the upstream side of the pump through a drain passage.

In this structure, for example, even if the fluid leaking into the crank chamber is vaporized by the heat generated at the sliding portion in the crank chamber, the vaporized fluid is directed to the upstream side of the first pump through the drain passage. Will be returned. Therefore, it is possible to avoid a situation in which the vaporized fluid in the crank chamber eventually accumulates in the cylinder bore and the fluid from the first pump cannot be sucked, and the reliability of the fluid pressure device is improved.

According to a sixth aspect of the present invention, in any one of the first to fifth aspects, the preferred embodiment of the first pump is limited. That is, the first pump is a gear pump or a centrifugal pump.

According to a seventh aspect of the present invention, in any one of the first to sixth aspects, the suction passage connected to the suction side of the first pump allows the gas generated in the suction passage to float to the upstream side. It is characterized by having possible forms.

In this structure, for example, even if cavitation occurs in the suction passage, the bubbles float up in the suction passage to the upstream side and are sucked into the first pump, and thus sucked into the second pump. It can be prevented from being done.

According to an eighth aspect of the present invention, the fluid pressure feeding device according to any one of the first to seventh aspects is provided, and the fluid stored inside can be delivered to the outside by the fluid pressure feeding device. It is a characteristic fluid storage tank.

In this structure, the fluid pressurizing device is integrated with the tank.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION First and second embodiments in which the present invention is applied to a fuel supply system for an internal combustion engine will be described below. In the second embodiment, only the differences from the first embodiment will be described, the same or corresponding members will be denoted by the same reference numerals, and description thereof will be omitted.

First Embodiment (Fuel Supply System for Internal Combustion Engine) FIG. 2 is a diesel type internal combustion engine (not shown) which is a driving source of a vehicle.
FIG. 3 is a schematic diagram showing a fuel supply system for supplying dimethyl ether (hereinafter referred to as DME) as a fuel to a fuel injection device 101 including, for example, an in-line piston pump, which is provided in FIG. This fuel supply system is
A fluid storage tank (hereinafter referred to as a tank) 11 for storing ME, and a fluid pressure feeding device provided in the tank 11 for feeding DME in the tank 11 in a liquid state toward the fuel injection device 101. Pump unit 12 as
It consists of The DME is a fluid that becomes a gas at a saturation pressure or lower, in other words, a fluid that becomes a gas at room temperature and atmospheric pressure.

(Outline of Pump Unit and Motor Section) As shown in FIG. 1, the housing of the pump unit 12 is joined and fixed to a pair of upper and lower center housings 21 and 22 and an upper end of an upper first center housing 21. And a second end housing 24 fixedly joined to the lower end of the second center housing 22 on the lower side. The pump unit 12 is inserted and fixed in a mounting hole 11 a that is provided through the lower portion of the tank 11 by the first end housing 23. The upper surface of the first end housing 23, in other words, a small part of the pump unit 12 is exposed inside the tank 11.

A crank chamber 25 is defined in the second center housing 22. The crank chamber 25 and the inside of the tank 11 are arranged from the first end housing 23 to the first
The center housing 21 is always communicated with each other through a drain passage 26 formed through the center housing 21. The same passage 26 is
It extends vertically between the tank 11 and the crank chamber 25.

A motor chamber 27 is defined in the second end housing 24. A drive shaft 28 is rotatably supported between the first center housing 21 and the second end housing 24 so as to pass through the crank chamber 25 and the motor chamber 27. The crank chamber 25 and the motor chamber 27 are blocked by a shaft sealing device 60 that seals the intermediate position of the drive shaft 28.

A stator 29 is fixed to the inner peripheral surface of the second end housing 24 in the motor chamber 27. Similarly, a rotor 30 is fixed to the outer peripheral surface of the drive shaft 28 in the motor chamber 27 at a position facing the stator 29. Therefore, this configuration forms the motor unit M as an electric motor, and the motor unit M is externally connected to the stator 2
When power is supplied to 9, the drive shaft 28 is rotationally driven via the rotor 30.

The pump unit 12 has a first
First pump portion P1 including a gear pump as a pump
And a second pump portion P2 including a piston pump as a second pump. The gear pump has a lower volumetric efficiency than the piston pump, but has a feature that it does not have an expansion (suction) stroke. Piston pump
Although it has an expansion stroke, it has the feature of higher volumetric efficiency than a gear pump. Therefore, the second pump portion P
2 is positioned as a main pump for pumping the DME toward the fuel injection device 101. In addition, the first pump portion P1 is D in the expansion stroke of the second pump portion P2.
It is positioned as a pump for pressurization to prevent vaporization of ME.

Both the pump parts P1 and P2 share the above-mentioned motor part M as a drive source. That is, the drive shaft 28 of the first pump unit P1 and the drive shaft 28 of the second pump unit
Are arranged on the same axis and are uniaxial,
The housings 21 to 24 of the pump parts P1 and P2 and the motor part M are integrated into one unit.
The DME discharge amount per one rotation of the drive shaft 28 in each of the pump parts P1 and P2 is set so that the relationship of the first pump part P1> the second pump part P2 is satisfied.

(First Pump Section of Pump Unit) As shown in FIG. 1, in the first pump section P1, a pump chamber 31 is defined at a joint portion of the first center housing 21 with the first end housing 23. ing. The upper end of the drive shaft 28 is disposed in a protruding manner in the pump chamber 31,
The first gear 32 is integrally rotatably fixed to the protruding portion. Further, in the pump chamber 31, a second gear 33 meshing with the first gear 32 is rotatably arranged in the same plane as the first gear 32.

On the upper surface of the first end housing 23, a suction port 34 is formed vertically above the pump chamber 31. In the first end housing 23, an intake passage 35 that connects the intake port 34 and the low-pressure side (left side in FIG. 3) of the pump chamber 31 is formed so as to extend in the vertical direction. In the first center housing 21, a communication passage 36 extending downward from the high pressure side of the pump chamber 31 (right side in FIG. 3) is formed. The communication passage 36 is
It is connected to the suction side of the second pump portion P2.

When the drive shaft 28 rotates, the first
The gear 32 is rotated, and the second gear 33 is rotated by the rotation of the first gear 32. Therefore, the tank 1
The DME that has flowed into the low-pressure side of the pump chamber 31 from the inside of 1 through the suction port 34 and the suction passage 35 has the respective gears 32, 33.
Is transferred toward the high pressure side of the pump chamber 31 by the transfer space formed between the tooth space of the pump chamber 31 and the inner surface of the pump chamber 31. The DME transferred to the high pressure side of the pump chamber 31 is discharged toward the communication passage 36.

As shown in FIG. 3, a pressure release passage 37 connecting the high pressure side of the pump chamber 31 and the inside of the tank 11 is formed in the first end housing 23 so as to extend in the vertical direction. . In the middle of the pressure release passage 37,
Relief valve 38 including a ball valve 38a and a spring 38b
Is provided. In the relief valve 38, the ball valve 38a normally closes the pressure release passage 37 by the urging force of the spring 38b. In the relief valve 38, when the pressure on the high pressure side of the pump chamber 31, that is, the pressure in the communication passage 36 becomes excessive, the ball valve 38a moves against the spring 38b to open the pressure release passage 37.

(Second Pump Section of Pump Unit) As shown in FIG. 1, the second pump section P2 has a crank chamber 25.
Inside, a cylinder block 39 is spline-fitted to the drive shaft 28 so as to be integrally rotatable and relatively movable in the axial direction. Drive shaft 2 in cylinder block 39
A plurality of cylinder bores 39a are formed around the circumference of the cylinder 8. A piston 40 is provided in each cylinder bore 39a.
Is housed. The second center housing 22 has a cam body 41 that is positioned below the crank chamber 25.
Is fixed. The drive shaft 2 is provided on the upper surface of the cam body 41.
An inclined surface 41a that is inclined with respect to the axis of 8 is formed.

A shoe 43 is connected to the piston 40 via a spherical joint 42. A valve plate 44 is fixed to the inner wall surface of the crank chamber 25 in the first center housing 21. Cylinder block 39
An accommodation chamber 39b is formed in the center of the. A pressing spring 45 is housed in the housing chamber 39b so as to surround the drive shaft 28. The spring force of the pressing spring 45 is
The spring block 46 acts on the cylinder block 39, and the spring block 47, the pin 48, and the pivot 49 act on the shoe retainer 50. Therefore, the shoe 43 on the shoe retainer 50 is attached to the slope 41 of the cam body 41.
While being pressed against a, the cylinder block 39 is pressed against the valve plate 44. This pressing force is
Along with the pressing force of the cylinder block 39 itself against the valve plate 44 caused by the pressure difference between the inside and outside of the cylinder bore 39a, the sealing property between the cylinder block 39 and the valve plate 44 is enhanced.

By rotating the cylinder block 39 integrally with the drive shaft 28, each piston 4
0 is reciprocated in a stroke defined by the inclination angle of the inclined surface 41a of the cam body 41, and the cylinder bore 3
9a are alternately communicated with the suction port 44a and the discharge port 44b, which are formed in the valve plate 44 and have an arc shape. As a result, D pressurized by the first pump portion P1
ME is sucked into the cylinder bore 39a from the suction port 44a through the communication passage 36, and the DME in the cylinder bore 39a is discharged from the discharge port 44b by the pumping action. The DME discharged from the discharge port 44b is
Discharge passage 5 formed in the first center housing 21
1 and the external pipe 13 to the fuel injection device 101.

The present embodiment having the above-mentioned structure has the following effects. (1) The drive source of the first pump portion P1 and the drive source of the second pump portion P2 are shared by the motor portion M. Therefore, the fuel supply system can be made compact and the configuration can be simplified, and the manufacturing cost thereof can be reduced, as compared with the case where the drive sources of the pump units P1 and P2 are separately provided. Further, the common use of the drive source of the first pump portion P1 and the drive source of the second pump portion P2 is advantageous in that both pumps P1 and P2, and thus the motor portion M, are made into one unit 12.

(2) The electric motor (motor portion) M has a simpler structure than an internal combustion engine or the like, and the housings 21 to 24 can be easily integrated with the pump portions P1 and P2. Also, the electric motor M is suitable as a drive source of the pump unit 12 for the fuel supply system from the viewpoint of safety.

(3) The drive shaft 28 of the first pump portion P1, the drive shaft 28 of the second pump portion P2, and further the output shaft 28 of the motor portion M are arranged on the same axis and are uniaxial. Therefore, for example, a complicated power transmission configuration is not required between the motor unit M and the second pump unit P2 and between the second pump unit P2 and the first pump unit P1, and the pump unit 1
The configuration of 2 can be simplified and the unit 12 can be downsized.

(4) In the communication passage 36 connecting the discharge side of the first pump portion P1 and the suction side of the second pump portion P2, an excessive pressure in the passage 36 is put in the tank 11 in other words, the first pump. Relief valve 38 that escapes to the upstream side of portion P1
Is attached. Therefore, the relief valve 38 can prevent an excessive increase in pressure in the communication passage 36, and can prevent the pressurization of the second pump portion P2 from becoming excessive and the power loss of the pump unit 12 to increase.

(5) Crank chamber 25 of the second pump portion P2
Is open to the inside of the tank 11 (in other words, upstream of the first pump portion P1) via the drain passage 26. Therefore, the DME that leaks into the crank chamber 25 will not move to the sliding portion (for example, the cam body 41 and the shoe 4) inside the crank chamber 25.
Even if vaporized by the heat generated in 3), the vaporized DME will be returned to the inside of the tank 11 through the vent passage 26. Therefore, it is possible to avoid a situation in which the vaporized DME in the crank chamber 25 eventually accumulates in the cylinder bore 39a and the suction of the DME from the suction port 44a becomes impossible, and the reliability of the pump unit 12 is improved. Also,
The vent passage 26 can prevent an excessive increase in pressure in the crank chamber 25.

It should be noted that the extraction passage 26 is formed in the crank chamber 2
5 is provided so as to extend vertically upward from 5 to ensure the vaporized DME in the crank chamber 25.
It can be said that this is a particularly effective passage form in that it can be lifted inward.

(6) In the pump unit 12, the suction passage 35 is provided so as to extend vertically upward from the pump chamber 31 of the first pump portion P1. Therefore, even if cavitation occurs in the suction passage 35, the bubbles rise in the tank 11, in other words, toward the upstream side of the passage 35, and are sucked into the first pump portion P1, and thus the second pump portion P1. It can prevent being inhaled by P2.

(7) The tank 11 has a pump unit 12
Are integrated. Therefore, the tank 11 and the pump unit 12 can be easily assembled to the vehicle. In addition, piping for connecting the tank 11 and the pump unit 12 is not required.

(8) The pump unit 12 is almost entirely exposed to the outside of the tank 11. Therefore, maintenance of the unit 12 becomes easy. Second Embodiment As shown in FIGS. 4 and 5, in the present embodiment, the pump unit 12 is entirely housed in the tank 11 and fixed to the bottom of the tank 11. Unlike the arrangement of the first embodiment in which the pump unit 12 is vertically oriented, that is, the drive shaft 28 is vertical, the pump unit 12 is disposed horizontally, that is, the drive shaft 28 is horizontal. Further, the discharge passage 51 of the pump unit 12 is communicated with a discharge port 52 penetrating the bottom of the tank 11, and is connected to the external pipe 13 via the discharge port 52. Furthermore, the passage 26
Are provided so as to penetrate the peripheral wall of the second center housing 22 and extend in the vertical direction.

In the present embodiment, the first pump portion P1
A centrifugal pump is used in the pump chamber 31, and an impeller 55 that constitutes the centrifugal pump is integrally rotatably fixed to the drive shaft 28 in the pump chamber 31. Therefore, the rotation of the impeller 55 accompanying the rotation of the drive shaft 28 causes the pump chamber 31 to pass through the suction port 34 and the suction passage 35 from the inside of the tank 11.
DME flows into the low-pressure side (left side in FIG. 5) of the. The DME flowing into the low pressure side of the pump chamber 31 is transferred to the high pressure side of the pump chamber 31 (upper side in FIG. 5) by the transfer space formed between the adjacent blades of the impeller 55 and the inner surface of the pump chamber 31. Be transferred to. The DME transferred to the high pressure side of the pump chamber 31 is discharged toward the communication passage 36 by the centrifugal force applied by the rotation of the impeller 55.

Also in this embodiment, the same effects as (1) to (5) and (7) of the first embodiment can be obtained. In addition, the following effects are achieved. (1) The entire pump unit 12 is housed in the tank 11. Therefore, there is no protrusion outside the tank 11, and the tank 11 and the pump unit 12 can be more easily assembled to the vehicle. Further, as is clear from comparison with FIG. 1, the extraction passage 26 can be shortened, and (5) of the first embodiment can be more effectively achieved. Furthermore, even if the suction passage 35 extends in the horizontal direction, the same effect as (6) of the first embodiment can be obtained. That is, the degree of freedom in setting the form of the suction passage 35 increases.

(2) The centrifugal pump used as the first pump portion P1 has a simple structure as compared with, for example, a gear pump. Therefore, the structure of the pump unit 12 can be simplified.

The following modes can also be implemented without departing from the spirit of the present invention. In addition to DME, CFCs, propane, and the like can be cited as fluids that become a gas at a saturated pressure or lower. That is, the present invention is embodied in a fluid pumping device for pumping freon or propane.

As the pump having no expansion stroke, a screw pump, a roots pump, etc. may be mentioned in addition to the gear pump and the centrifugal pump. That is, use a screw pump or a roots pump as the first pump.

In each of the above embodiments, the pressure release passage 37 and the relief valve 38 may be omitted. in this case,
In each of the pump parts P1 and P2, the DME discharge amount per one rotation of the drive shaft 28 is set so that the relationship of the first pump part P1 = the second pump part P2 is established.

In each of the above embodiments, the second pump portion P2 (crank chamber 25) and the motor portion M (motor chamber 2)
7) is provided with a shaft sealing device 60 (see FIG. 1), but the coaxial sealing device 60 is omitted and the motor chamber 27 is also DME.
Good atmosphere.

In each of the above embodiments, the motor unit M should be independent of the pump unit 12. In this case, the motor section M and the drive shaft 28 of the pump unit 12 are operatively connected via a power transmission mechanism such as a pulley and a belt.

The technical idea that can be understood from the above embodiment will be described. (1) The fluid storage tank according to claim 8, wherein substantially the entire fluid pumping device is exposed outside the tank.

(2) The fluid storage tank according to claim 8, wherein the fluid pressure feeding device is housed and arranged in the tank. (3) A fuel supply system for an internal combustion engine, comprising the fluid storage tank according to claim 8 or (1) or (2) as a fuel tank.

(4) A vehicle characterized in that the internal combustion engine is used as a drive source and the fuel supply system of (3) is used to supply fuel to the internal combustion engine. (5) The fuel supply system according to (3), wherein the internal combustion engine is a diesel type, or the vehicle according to (4).

[0054]

According to the present invention having the above structure, the drive source of the first pump and the drive source of the second pump are shared.
Therefore, as compared with the case where a drive source for each pump is separately provided, the fluid pressure feeding device can be downsized and the configuration can be simplified, and the manufacturing cost can be reduced. Further, the common use of the drive source of the first pump and the drive source of the second pump is advantageous in that both pumps and, in turn, the drive sources are made into one unit.

[Brief description of drawings]

FIG. 1 is a sectional view of a pump unit.

FIG. 2 is a schematic diagram of a fuel supply system.

FIG. 3 is a sectional view taken along line 1-1 of FIG.

FIG. 4 is a schematic diagram of a fuel supply system according to a second embodiment.

FIG. 5 is a partial sectional view of a pump unit.

[Explanation of symbols]

12 ... Pump unit as a fluid pumping device, P1 ... 1st pump part as a 1st pump, P2 ... 2nd pump part as a 2nd pump, M ... Motor part as a drive source.

Continued front page    F-term (reference) 3D038 CA15 CB01 CC06 CC18                 3H070 AA02 BB04 BB06 CC34 CC35                       DD32 DD91 DD93                 3H071 AA07 BB01 BB02 BB03 BB12                       BB13 BB14 BB15 CC33 CC34                       DD72 DD74 DD83 DD84

Claims (8)

[Claims] 1. A fluid pumping device used for pumping a fluid which becomes a gas at a saturated pressure or lower, wherein a first pump having no expansion stroke and a suction side connected to a discharge side of the first pump. , A second pump having an expansion stroke, wherein the drive source of the first pump and the drive source of the second pump are made common. 2. The drive source is an electric motor, and the housing of the electric motor, the housing of the first pump, and the housing of the second pump are integrated.
The fluid pressure-feeding device according to. 3. The fluid pumping device according to claim 1, wherein the drive shaft of the first pump and the drive shaft of the second pump are arranged on the same axis and are uniaxial. 4. A relief valve is provided in a communication passage that connects the discharge side of the first pump and the suction side of the second pump so as to release an excessive pressure in the passage to an upstream side of the first pump. The fluid pressure feeding device according to any one of claims 1 to 3. 5. The second pump comprises a piston pump, and a crank chamber for accommodating a cam body for converting a rotational movement of a drive shaft into a reciprocating movement of a piston is defined in a housing of the second pump. The fluid pressure feeding device according to claim 1, wherein the crank chamber and the upstream side of the first pump are connected via a drain passage. 6. The fluid pumping device according to claim 1, wherein the first pump is a gear pump or a centrifugal pump. 7. The suction passage connected to the suction side of the first pump has a form capable of lifting the gas generated in the suction passage to the upstream side.
The fluid pressure feeding device according to any one of 6 above. 8. A fluid storage device comprising the fluid pressure feeding device according to claim 1, wherein the fluid stored inside can be delivered to the outside by the fluid pressure feeding device. For tank.