JPH0996277A - Bellows pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a stable flow characteristic by providing an extensible/ contractible bellows, which partitions the first working chamber having a suction/delivery valve of transfer feed fluid, and, the second working chamber charged with an operating fluid, and, forming a reservoir chamber in an upper side from the second working chamber, go as to easily discharge a bubble generated, in the second working chamber. SOLUTION: An eccentric cam 37 is rotated, by rotating a drive shaft 38, a lift amount of the eccentric cam 37 is transmitted to a plunger 32 through a seat cam 40. By a stroke of the plunger 32 from a side of a reservoir chamber 28 to a side of the second working chamber 5, a communication hole 34 formed in a barrel part of the plunger 32 is closed, by an internal peripheral surface of a cylinder hole 31, and a pressure in the second working chamber 5 rises. In this way, a bellows 19 partitioning the first/second working chambers 4, 5 is press contracted, a pressure in the first working chamber 4 rises. A spherical valve 16 of a delivery valve 12 is separated, against a spring 17 from a valve seat 14a of a hollow plug 14, the delivery valve 12 is opened, and a fluid, is delivered to a delivery port through the delivery valve 12 and a delivery passage 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bellows pump applied as a fluid pump.

[0002]

2. Description of the Related Art As this type of bellows pump, for example, the one described in JP-A-4-321781 is known. In this pump, as shown in FIG. 4, an expandable bellows c is arranged in a cylinder chamber b in which a piston a is housed so that it can reciprocate.
The inside is partitioned into a first working chamber f having a suction valve d and a discharge valve e for the transfer fluid, and a second working chamber g in which the piston a is arranged, and the piston a is reciprocally moved to produce a second
The bellows c is expanded / contracted via the working fluid in the working chamber g, and the volume in the first working chamber f is expanded / contracted in accordance with this expansion / contraction operation to give a pumping action to the transfer fluid.

[0003]

However, in the above-mentioned conventional example, the oil storage chamber h for the working fluid in the second working chamber g has the oil housing j separate from the pump body i and the side of the cylinder chamber b. Further, a communication hole k between the oil storage chamber h and the second working chamber g is formed in the pump body i and opens relatively below the second working chamber g.

Therefore, when a bubble is generated in the second working chamber g due to aeration or the like, the bubble is communicated with the communication hole k.
It is difficult for the oil to be discharged into the oil storage chamber h through the above, and there is a risk that it will stay above the second working chamber g.

Then, the pressure characteristic in the second working chamber g is disturbed due to the reciprocating movement of the piston a, and the operation of the bellows c which expands and contracts due to the pressure in the second working chamber g becomes unstable. As a result, The flow rate characteristic of the transferred fluid will become unstable.

Further, since the communication hole k is formed in the pump body i, the length of the communication hole k becomes long, which may make the processing difficult.

Further, since the oil storage chamber h is formed with a separate oil housing j on the side of the cylinder chamber b, the size of the pump may be increased.

The present invention has been devised in view of the above-mentioned conventional circumstances, and it is easy to discharge bubbles generated in the second working chamber,
An object of the present invention is to provide a bellows pump that can prevent the flow characteristics of the transferred fluid from becoming unstable and can be downsized.

[0009]

SUMMARY OF THE INVENTION Therefore, according to the present invention, there is provided an expandable bellows for partitioning a first working chamber having a suction valve and a discharge valve for a transfer fluid and a second working chamber filled with the working fluid, A reservoir chamber for working fluid in the second working chamber formed above the second working chamber, a cylinder hole having both ends open to the reservoir chamber and the second working chamber, and in the cylinder hole, A bottomed cylindrical plunger that is accommodated and arranged so as to be able to reciprocate under a one-way bias by a spring means, and a communication that is formed in the body of the plunger and that communicates the cylindrical interior of the plunger with the reservoir chamber. The hole and the driving means for reciprocating the plunger are provided.

The dependent claims relate to advantageous embodiments of the invention.

A coil spring is preferably used as the spring means for urging the bottomed cylindrical plunger in one direction, that is, the reservoir chamber side or the second working chamber side, in order to obtain a long stroke of the plunger. To be done.

Further, as the driving means for reciprocating the plunger, a rotationally driven eccentric cam or an electromagnetic solenoid can be applied. The drive means, in conjunction with the spring means associated with the plunger, will drive the plunger against the bias of the spring means.

In this bellows pump, the plunger is reciprocally driven in the cylinder hole by the driving means. At this time, the communication hole formed in the body portion of the plunger at a predetermined stroke of the plunger is closed by the inner peripheral surface of the cylinder hole, and the communication between the reservoir chamber and the second working chamber is performed through the communication hole and the cylindrical inside of the plunger. Is cut off. In this state, the stroke of the plunger toward the second working chamber increases the pressure in the second working chamber corresponding to the volume of the plunger that has entered the second working chamber. Second
Due to the pressure increase in the working chamber, the expandable bellows is compressed and the pressure in the first working chamber increases. The discharge valve is opened due to the pressure increase in the first working chamber, and the fluid (transfer fluid) in the first working chamber is discharged through the discharge valve.

Subsequently, the plunger returns to the reservoir chamber side from the second working chamber side by the spring force of the spring means attached to the plunger, so that the second actuation of the plunger corresponds to the volume withdrawn from the second working chamber. The pressure in the room drops.
Due to the pressure decrease in the second working chamber, the expandable bellows extends toward the second working chamber, and the pressure in the first working chamber decreases. The suction valve is opened due to the pressure drop in the first working chamber,
The transferred fluid is introduced into the first working chamber through the suction valve to prepare for the next discharge operation.

When the plunger strokes to the reservoir chamber side by a predetermined amount, the communication hole closed by the inner peripheral surface of the cylinder hole opens again in the reservoir chamber, and the second working chamber and the reservoir chamber communicate with each other. However, during the stroke of the plunger, the working fluid in the second working chamber is not discharged while being filled in the second working chamber. Therefore, even if the communication hole is opened to the reservoir chamber, the working fluid is normally operated from this communication hole. The fluid is not sucked in, and the amount of the working fluid in the second working chamber becomes constant only when the volume of the working fluid in the second working chamber changes due to temperature change or the like during the stroke of the plunger. The working fluid is exchanged between the second working chamber and the reservoir chamber through the communication hole.

At the same time, when bubbles are generated in the second working chamber due to aeration or the like, since the reservoir chamber is formed above the second working chamber, the bubbles pass through the cylindrical inside of the plunger and the communication hole. It is quickly discharged into the reservoir chamber.

Thereby, the bubbles do not stay in the second working chamber and the pressure characteristic in the second working chamber becomes stable, so that the stable flow rate characteristic of the transferred fluid can be obtained.

Further, since the communication hole is provided in the body portion of the plunger, the degree of freedom in selecting the diameter and length of the communication hole is increased, the formation is facilitated, and the communication hole is opened. Since the reservoir chamber can be formed inside the pump body, the size of the pump can be reduced.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will now be described in detail with reference to the drawings as an embodiment in which a fuel pump for an automobile is applied.

FIG. 1 is a sectional view of a bellows pump showing an embodiment of the present invention. In the figure, reference numeral 1 denotes a pump body, which is composed of an upper pump body 2 and a lower pump body 3 integrally connected to the upper pump body 2 by bolts (not shown). Four
1 is a first working chamber formed inside the pump body 1, 5 is also a second working chamber, and the second working chamber 5 is filled with working fluid.

Reference numeral 6 denotes a suction valve for the transfer fluid, that is, fuel, provided in the first working chamber 4, and the suction valve 6 is used for the first working chamber 4.
A ball valve 9 is pressed by a check spring 10 against a valve seat 8a of a hollow plug 8 provided between the suction passage 7 and the suction passage 7. Reference numeral 11 denotes a plug screwed and fixed to the pump body 1, which also serves as a spring receiver for the check spring 10.

A discharge valve 12 is also provided in the first working chamber 4, and the discharge valve 12 is a ball valve on a valve seat 14a of a hollow plug 14 provided between the first working chamber 4 and the discharge passage 13. 16
Is pressed by a check spring 17. 18 is a plug screwed and fixed to the pump body,
It also serves as a spring receiver for the check spring 17.

Numeral 19 is an expandable bellows which divides the first working chamber 4 and the second working chamber 5, and the bellows 19 is made of a metallic material, and a bottom plate 20 is attached to one end thereof to form a bottomed cylinder as a whole. The upper open end 21 is attached to the bottom 24 of the hollow plug 23 which is screwed and fixed to the screw hole 22 of the first working chamber 4. Therefore, the inside of the bellows 19 is the first working chamber 4 and the outside is the second working chamber 5. A hollow sheet 25 is provided in the screw hole 22, and the coil spring 26 is compressed between the sheet 25 and the bottom plate 20 of the bellows 19 by penetrating the hollow inside of the hollow plug 23. The coil spring 26 urges the bellows 19 to extend toward the second working chamber 5, and the bottom plate 20 is in contact with the bottom surface 27 of the second working chamber 5.

28 is a reservoir chamber for the working fluid in the second working chamber 5, and the reservoir chamber 28 is formed above the second working chamber 5 (upward in the direction of gravity). In addition, an opening 29 for filling the working fluid into the reservoir chamber 28 is provided above the reservoir chamber 28, and is sealed by a screw plug 30.

Reference numeral 31 is a cylinder hole formed in the pump body 1, and both ends of this cylinder hole 31 are the second working chamber 5
The inside and the inside of the reservoir chamber 28 communicate with each other.

Reference numeral 32 denotes a plunger accommodated and arranged in the cylinder hole 31 so as to be reciprocally movable.
Has a bottomed tubular shape as a whole, a tubular interior 33 opens toward the second working chamber 5 side, and a tubular interior 3 is provided in the body of the plunger 32.
3 and the reservoir chamber 28 are communicated with each other through a communication hole 34 formed in the radial direction. The diameter dimension of the communication hole 34,
The formation position, the formation quantity, etc. are appropriately selected according to the desired pump performance. Further, the plunger 32 has a coil spring (spring means) for urging the plunger 32 in one direction.
35 is attached, and the coil spring 35 biases the plunger 32 toward the reservoir chamber 28.
Reference numeral 36 denotes a spring receiving member for the coil spring 35, which is screwed and fixed to the lower housing 3.

Reference numeral 37 denotes an eccentric cam as a driving means for reciprocating the plunger 32. The eccentric cam 37 is
It is formed integrally with the drive shaft 38 housed in the reservoir chamber 28 and is in contact with the sealed bottom surface of the plunger 32 via a flat bearing 39 and a seat cam 40.

The first working chamber 4, the second working chamber 5, the suction valve 6, the discharge valve 12, the bellows 19, the plunger 32 and the eccentric cam 37 constitute one bellows pump, and in this embodiment. Each of these components is shown in FIGS.
As shown in FIG. 3, three sets are provided in the pump body 1 and three bellows pumps are arranged in the axial direction.
Each of the suction valves 6 of these three bellows pumps is
As shown in FIG. 2, it communicates with a common suction passage 7, and this suction passage 7 communicates with a suction port to which a fuel tank (not shown) is connected. Further, the discharge passages 13 of the discharge valve 12 are communicated with each other by a passage 42 and a discharge port 43.

Eccentric cams 37 for driving the plungers 32 of the bellows pumps are provided corresponding to the plungers 32, and the maximum lift positions of the eccentric cams 32 are shifted by 120 degrees in the rotational direction of the eccentric cams. is there.

Reference numerals 44 and 45 are bearings for supporting the drive shaft 38, and 46 is a seal member.

In such a structure, the eccentric cam 37 is rotated by the rotation of the drive shaft 38, and the seat cam 40 is rotated.
The lift amount of the eccentric cam 37 is transmitted to the plunger 32 via this, and the plunger 32 reciprocates under the bias of the spring force of the coil spring 35. As a result, the pressure in the second working chamber 5 changes, and the first working chamber 4 and the second working chamber 5 change.
The bellows 19 that separates and expands and contracts, and along with this, the first
The pressure in the working chamber 4 changes, and the transfer fluid (fuel) in the first working chamber 4 is pumped.

That is, from the state shown in FIG. 1, the drive shaft 38 rotates and the eccentric cam 37 causes the plunger 32 to move to the second working chamber 5.
Push to the side. The plunger 32 is second from the reservoir chamber 28 side.
By making a predetermined stroke to the side of the working chamber 5, the communication hole 34 formed in the body portion of the plunger 32 is closed by the inner peripheral surface of the cylinder hole 31, and the communication hole 34 and the cylindrical interior 33 of the plunger 32 pass through. , Reservoir chamber 2
The communication between the inside of 8 and the inside of the second working chamber 5 is cut off. When the plunger 32 further strokes to the second working chamber 5 side in this state, the pressure in the second working chamber 5 increases corresponding to the volume of the plunger 32 entering the second working chamber 5.

As the pressure in the second working chamber 5 rises, the expandable bellows 19 is compressed and the pressure in the first working chamber 4 increases. Due to the pressure increase in the first working chamber 4, the ball valve 16 of the discharge valve 12 moves against the spring force of the check spring 17 and moves away from the valve seat 14a of the hollow plug 14 to open the discharge valve 12, The transfer fluid (fuel) in the first working chamber 4 is discharged to the discharge port 43 via the discharge valve 12 and the discharge passage 13.

When the drive shaft 38 further rotates and the lift amount of the eccentric cam 37 is reduced, the plunger 32 is biased by the spring force of the coil spring 35 to move from the second working chamber 5 side to the reservoir chamber 28 side. Return. As a result, the pressure in the second working chamber 5 decreases corresponding to the volume of the plunger 32 withdrawn from the second working chamber 5. Due to the pressure drop in the second working chamber 5, the expandable bellows 19 causes the coil spring 2 to move.
Under the urging force of 6, the pressure in the first working chamber 4 decreases as it extends toward the second working chamber 5 side. Due to the pressure drop in the first working chamber 4, the ball valve 9 of the suction valve 6 moves against the spring force of the check spring 10 and moves away from the valve seat 8a of the hollow plug 8 to open the suction valve 6. The transfer fluid (fuel) is guided from the suction port 41 into the first working chamber 4 via the suction passage 7 and the suction valve 6 to prepare for the next discharge operation.

When the plunger 32 strokes toward the reservoir chamber 28 by a predetermined amount, the communication hole 34 closed by the inner peripheral surface of the cylinder hole 31 reopens to the reservoir chamber 28, and the second working chamber 5 and the reservoir chamber 28 are opened. Communicates with. However, during the stroke of the plunger 32, the working fluid in the second working chamber 5 is not discharged while being filled in the second working chamber 5, so that the communication hole 34 is formed in the reservoir chamber 28.
Normally, the working fluid is not sucked from the communication hole 34, and only when the volume of the working fluid in the second working chamber 5 changes due to temperature change or the like during the stroke of the plunger 32. , The second working chamber 5 and the reservoir chamber 28 so that the amount of working fluid in the second working chamber 5 becomes constant.
The working fluid is exchanged with the inside through the communication hole 34.

At the same time, when bubbles are generated in the second working chamber 5 due to aeration or the like, since the reservoir chamber 28 is formed above the second working chamber 5, the bubbles are formed inside the cylindrical shape of the plunger 32. It is quickly discharged into the reservoir chamber 28 via 33 and the communication hole 34.

As a result, the bubbles do not stay in the second working chamber 5 and the pressure characteristic in the second working chamber 5 becomes stable, so that a stable flow rate characteristic of the transfer fluid (fuel) can be obtained. Especially when the transfer fluid is fuel such as gasoline, there is a possibility that problems such as vapor lock may occur when the flow rate characteristic becomes unstable. According to this embodiment, this can be solved advantageously.

Further, since the communication hole 34 is provided in the body portion of the plunger 32, the degree of freedom in selecting the diameter and length of the communication hole 34 is increased, the formation is facilitated, and the communication hole is formed. Since the reservoir chamber 28 having the opening 34 can be formed inside the pump body 1, the size of the pump can be reduced.

Further, since the drive shaft 38 having the eccentric cam 37 is accommodated in the reservoir chamber 28, the reservoir chamber 28 also serves as the accommodating chamber of the drive shaft 38.
It becomes unnecessary to form a housing chamber for the special drive shaft 38,
The size and cost of the pump can be advantageously reduced.

Furthermore, three bellows pumps are configured to be driven by one drive shaft 38, and the maximum lift positions of the eccentric cams 37 corresponding to the respective pumps are arranged at equal intervals in the rotational direction, and Since the suction passage 7 and the discharge passage 13 of each pump are communicated with each other, the pulsation of suction and discharge can be prevented as much as possible.

Although the embodiment has been described with reference to the drawings, the specific configuration is not limited to this embodiment, and can be changed without departing from the spirit of the invention.
For example, the eccentric cam 37 that is rotationally driven has been described as the drive unit that reciprocates the plunger 32, but an electromagnetic solenoid can be applied. In this case, in relation to the spring means attached to the plunger, it can be arbitrarily selected whether the plunger is pushed toward the second working chamber side or pulled toward the reservoir chamber side.

Further, the embodiment in which the respective suction passages 7 and discharge passages 13 of the three bellows pumps are communicated with each other has been described, but the respective suction passages and discharge passages may be provided independently. . In this case, each pump can handle different transfer fluids and supply the transfer fluids to the respective actuators.

Further, although the coil spring 26 attached to the bellows 19 is arranged on the first working chamber 4 side, it may be arranged on the second working chamber 5 side. Also, by utilizing the elastic force of the bellows 19 itself,
It is also possible to eliminate the coil spring 26.

[0044]

As described above in detail, according to the present invention, it is possible to easily discharge the bubbles generated in the second working chamber and prevent the flow characteristic of the transferred fluid from becoming unstable. It is possible to obtain a bellows pump that can be downsized.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a bellows pump showing an embodiment of the present invention, which is a cross-sectional view taken along the line CC of FIG.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a sectional view taken along line BB of FIG.

FIG. 4 is a drawing showing a conventional example.

[Explanation of symbols]

 4 1st working chamber 5 2nd working chamber 6 Suction valve 12 Discharge valve 19 Bellows 28 Reservoir chamber 31 Cylinder hole 32 Plunger 33 Cylindrical interior 34 Communication hole 35 Coil spring (spring means) 37 Eccentric cam (driving means)

Claims (3)

[Claims] 1. An expandable bellows for partitioning a first working chamber having a suction valve and a discharge valve of a transfer fluid and a second working chamber filled with the working fluid, and a bellows formed above the second working chamber. A reservoir chamber for the working fluid in the second working chamber, a cylinder hole whose both ends open into the reservoir chamber and the second working chamber, and a unidirectional biasing force of a spring means in the cylinder hole. Reciprocatingly moving the plunger, and a bottomed cylindrical plunger that is reciprocally accommodated and arranged, and a communication hole that is formed in the body of the plunger and that communicates the cylindrical interior of the plunger with the reservoir chamber. Drive means,
A bellows pump characterized by comprising: 2. The bellows pump according to claim 1, wherein the drive means is an eccentric cam that is rotationally driven. 3. The bellows pump according to claim 2, wherein the eccentric cam is housed and arranged in the reservoir chamber.