JP7015467B2 - Fluid pump - Google Patents

Description

The present invention relates to a fluid pump mounted on a vehicle or the like and capable of significantly reducing the pulsation of discharge pressure when supplying various fluids such as hydraulic oil.

Conventionally, as a fluid pump aimed at reducing the pulsation of such discharge pressure, for example, there is one described in Patent Document 1 below.

The fluid pump described in Patent Document 1 includes a cylinder forming a pump chamber, a plunger slidably provided inside the cylinder and urged toward the bottom dead center side by a spring, and the plunger. It is equipped with a mover that touches and hits the plunger in the pushing direction. This mover is reciprocally driven by a motor having a crank mechanism.

The pump chamber is connected to a suction passage for sucking the fluid into the pump chamber via the suction valve and a discharge passage for discharging the fluid liquid from the pump chamber via the discharge valve. The intake valve and the discharge valve are check valves.

When the mover pushes the plunger, in the discharge path, the fluid in the pump chamber is opened and operated to be discharged to the outside, and in the suction path, the suction valve is closed so that the fluid in the pump chamber does not flow back. On the contrary, when the mover is pulled, the mover is separated from the plunger, and the plunger protrudes from the cylinder by the urging force of the spring.

In the pump of this configuration, the discharge and interruption of the fluid are repeated as the plunger reciprocates, and pulsation occurs in the flow of the discharged fluid. Therefore, in the technique according to Patent Document 1, by using a resin tube as a discharge path, the elasticity of the tube is utilized to reduce the pulsation of the fluid. Further, as another method, there is a description that a buffer tank is provided in the discharge path to reduce the pulsation of the fluid.

WO2007 / 015429A

However, in the fluid pump of Patent Document 1, a check valve is used as an intake valve and a discharge valve for controlling the flow direction of the fluid. In this check valve, when the flow of fluid is stopped, a part of the valve body comes into contact with the valve seat provided on the inner surface of the pipe to shut off the pipe, and when the fluid is circulated, a part of the valve body is a valve. Separate from the seat. On the opposite side of the valve seat, a regulating part for regulating the position of the valve body separated from the valve seat is provided.

In the technique of Patent Document 1, the mover reciprocates at high speed by a motor, and a striking force is momentarily applied to the plunger, particularly when the fluid is discharged. At this time, the pressure of the fluid rises sharply, and the suction valve and the discharge valve operate rapidly to generate a tapping sound that collides with the valve seat and the regulation portion.

As described above, in the above-mentioned conventional technique, although the pulsation of the hydraulic pressure generated from the fluid pump can be reduced, a violent tapping sound is generated from a part of the pump.

Further, although there is a possibility that pulsation and vibration may be reduced at the place where the resin tube is arranged, vibration due to pulsation occurs in the pump body. Therefore, when paying attention to the entire pump, it cannot be said that the vibration and noise are eliminated.

As described above, the conventional fluid pump has a limit in reducing vibration and noise, and a compact fluid pump that solves this limit is required.

(Characteristic composition)
In the fluid pump according to the present invention,
A cylinder provided with at least one first opening for sucking and discharging the fluid once stored and at least one second opening for permitting and blocking the flow of the fluid.
A piston provided with a communication passage that reciprocates while forming a fluid chamber inside the cylinder and that communicates with the second opening and circulates the fluid in a direction intersecting the direction of the reciprocating movement.
A plurality of plunger units having a supply path and a discharge path for supplying and discharging the fluid to and from the fluid chamber through the first opening.
The plurality of plunger units are provided with a cam for driving and controlling the reciprocating motion of each of the pistons so as to be different from each other by a quarter cycle.
The supply path and the discharge path of a specific plunger unit among the plurality of plunger units are connected to the second opening of the other plunger units of the plurality of plunger units.
The supply path and the discharge path of the other plunger unit may be connected to the second opening of the specific plunger unit.

(effect)
As in this configuration, at least two sets of pistons and cylinders that discharge fluid are arranged, and the fluid suction / discharge function and the flow path switching function are shared with each other, thereby reducing the total number of parts. However, it is possible to form a fluid pump having a predetermined discharge amount. In this case, the overall size becomes compact, and a fluid pump having excellent mountability on a vehicle or the like can be obtained.

Further, by using a plurality of pistons to make a difference in the discharge timing of the fluid, it is possible to suppress the pulsation of the hydraulic pressure at the time of discharging the fluid, and it is possible to obtain a fluid pump with less vibration and noise.

Explanatory drawing which shows the structure and operation mode of the fluid pump which concerns on 1st Embodiment Bluff showing the difference in operating phase between piston and valve body Explanatory drawing showing the opening shape of the valve body and the change in the instantaneous suction discharge amount Explanatory drawing which shows the structure of the fluid pump which concerns on 2nd Embodiment Explanatory drawing which shows the structure of the fluid pump which concerns on 3rd Embodiment

[First Embodiment]
(Overview)
The first embodiment of the fluid pump S according to the present invention will be described with reference to FIGS. 1 to 3. As shown in FIG. 1, the fluid pump S includes a plunger P having at least one opening 21 for supplying and discharging the fluid W. The plunger P includes a cylinder 2 and a piston 1 that reciprocates while forming a fluid chamber 22 inside the cylinder 2. The drive state of the piston 1 is controlled by the rotating cam C. In the present embodiment, one flow path R is connected to the cylinder 2, and after that, a supply path R1 for supplying the fluid W to the fluid chamber 22 and a discharge path for discharging the fluid W from the fluid chamber 22. It branches to R2. The supply path R1 and the discharge path R2 are switched by a switching valve KV driven by the cam C.

(Plunger)
As shown in FIG. 1, the plunger P of the present embodiment has, for example, a simple shape in which a piston 1 is inserted inside a cylindrical cylinder 2 so as to be reciprocating along a reciprocating shaft core X1. The cylinder 2 and the piston 1 form a fluid chamber 22 for accommodating the fluid W. Inside the fluid chamber 22, a first spring 3a that abuts between the wall portion of the cylinder 2 and the end portion of the piston 1 and urges the piston 1 toward the cam C is provided. The first spring 3a is, for example, a coil spring.

The flow path R is connected to the wall portion of the cylinder 2 at a position that does not overlap with the movement locus of the piston 1. When the cam C rotates, the fluid W is sucked in or discharged into the inside of the cylinder 2 through the flow path R. When there is only one flow path R, if the flow path R is connected to the end face of the cylinder 2 orthogonal to the reciprocating shaft core X1 as shown in FIG. 1, the fluid W can flow in and out smoothly. Resistance is reduced.

(cam)
The piston 1 is driven by a rotating cam C. The cam C of the present embodiment is, for example, an eccentric cam having a circular outer shape. The cam C is provided with a rotation shaft (not shown), and is rotationally driven around the rotation shaft core X by an arbitrary drive mechanism. FIG. 2 shows an operation mode of the piston 1 by the cam C. The horizontal axis is the rotation angle of the cam C, and the vertical axis is the stroke of the piston 1. The operation curve of the piston 1 becomes a sine curve in this way. The points a to d in this curve indicate the position of the piston 1 in each of the states (a) to (d) of FIG.

(Switching valve)
A switching valve KV for switching the direction of the fluid W is provided in the middle of the flow path R through which the fluid W supplied to the cylinder 2 and the fluid W discharged from the cylinder 2 flow. Specifically, as shown in FIG. 1, it includes a cylindrical casing K and a valve body V that reciprocates while being guided on the inner surface of the casing K by the action of the cam C. Inside the casing K, a coil spring is provided as a second spring 3b that constantly presses the valve body V toward the cam C. Further, a ventilation hole K1 is provided in the casing K so as not to communicate the inside and the outside of the casing K and hinder the movement of the valve body V.

The casing K is provided with a valve opening K2 forming a supply path R1 and a discharge path R2. On the outer peripheral surface of one of the valve bodies V, an annular groove portion 4a as a communication passage 4 through which the fluid W flows is formed. That is, the valve body V reciprocates, and the flow path R is switched by changing the overlapping state of the supply path R1 or the discharge path R2 and the groove portion 4a.

In the case of this configuration, the valve body V is not operated by the pressure of the fluid W as in the conventional one-way valve, but is driven by the cam C independent of the flow of the fluid W. The direction in which the pressure of the fluid W acts on the valve body V is a direction perpendicular to the reciprocating movement direction of the valve body V. Therefore, the valve body V is not easily affected by the pressure of the fluid W, and there are inconveniences such as the oil violence that the valve body V collides with the valve seat and the like, and the valve body V generating a tapping sound with the casing K. Does not occur either. As described above, with the valve body V having the present configuration, it is possible to obtain a switching valve KV having a simple configuration and stable reciprocating operation.

(Operation mode of piston and valve body)
The valve body V and the piston 1 are driven with a difference of a quarter cycle per rotation cycle of the cam C. For example, in both the case where the piston 1 is pushed up by the cam C and the case where the piston 1 is pushed down by the first spring 3a, the moving speed of the piston 1 when the piston 1 is substantially in the middle between the top dead center and the bottom dead center. Is the maximum and the flow rate of the fluid W is the maximum. Therefore, if the supply path R1 or the discharge path R2 of the switching valve KV is fully opened at this time, the flow resistance of the fluid W becomes the minimum. Therefore, in this configuration, the timings of the cams C acting on the piston 1 and the valve body V are different by a quarter cycle.

The lower part of FIG. 2 shows the reciprocating motion of the valve body V. The points a to d here correspond to the states (a) to (d) in FIG. Further, by driving the piston 1 and the valve body V with a periodic difference by one cam C in this way, the increase / decrease in the suction / discharge flow rate of the fluid W by the piston 1 and the communication passage 4 of the valve body V It is possible to link the increase / decrease in the opening area of. As a result, in the switching valve KV, the fluid pressure is suppressed from suddenly increasing or decreasing, and the fluid pump S having low flow resistance can be obtained.

In the fluid pump S of the present embodiment, as shown in FIG. 1, the groove portion 4a, which is the communication passage 4, is provided along the direction of reciprocating movement of the guide surface Va provided on the outer surface of the valve body V. Provide it in the center position.

In particular, when the fluid W is hydraulic oil or the like, the hydraulic oil diffuses into the gap between the guide surface Va of the valve body V and the inner surface of the casing K. Thereby, the sliding resistance of the valve body V can be reduced. In this configuration, since the connecting passage 4 is provided at the center position of the guide surface Va, the hydraulic oil diffused from this is easily diffused to the entire surface of the guide surface Va. Therefore, with this configuration, the sliding resistance of the valve body V can be kept small and the operability of the valve body V can be improved.

(Shape of valve opening)
In order to further reduce the increase in flow resistance in the communication passage 4 of the valve body V, it is effective to devise the opening shape of the valve opening K2 provided in the casing K. When the opening shape of the supply path R1 and the discharge path R2 with respect to the casing K moves in a direction in which the groove portion 4a increases the overlapping area with the supply path R1 or the discharge path R2, the supply path R1 intersects with the edge portion of the groove portion 4a. Alternatively, it is convenient that the discharge path R2 is formed so as to be wider toward the inner side in the direction of increasing opening width.

This changes the overlapping area between the communication passage 4 of the valve body V and the supply passage R1 or the communication passage 4 and the discharge passage R2 when the valve body V reciprocates, and the discharge amount of the fluid W is changed according to the position of the piston 1. Is to deal with the change. In the present embodiment, when the communication passage 4 of the valve body V is the groove portion 4a, the opening shape of the supply path R1 that overlaps the groove portion 4a is assumed to be widened as the overlap with the groove portion 4a increases. There is.

FIG. 3 shows how the instantaneous suction / discharge flow rate of the fluid W in the cylinder 2 changes depending on the opening shape of the valve opening K2 formed in the casing K. The upper figure of FIG. 3 shows the transition of the overlapping state of the valve opening K2 and the groove 4a when the groove 4a of the valve body V moves relative to the valve opening K2 whose shape is quadrangular, circular, or substantially triangular. Shows. FIG. 3 shows a state in which the upper surface 4a1 of the groove portion 4a coincides with the end portion of each valve opening K2, and the valve opening K2 has not yet opened. On the other hand, each dotted line overlapping each valve opening K2 shows how the groove 4a moves to increase the opening area with the valve opening K2. The lower part of FIG. 3 shows the change mode of the instantaneous suction / discharge amount of the fluid W in the cylinder 2 according to the rotation of the cam C for each shape of the valve opening K2.

The valve body V reciprocates while constantly changing the speed according to the rotation of the cam C. The groove portion 4a of the valve body V changes the overlapping region with the valve opening K2, and when the valve body V reaches the top dead center, the opening area between the groove portion 4a and the valve opening K2 becomes maximum. It is desirable that the shape of the opening region of the valve opening K2 changes according to the flow rate of the fluid W sucked and discharged to the cylinder 2. That is, if the opening area of the valve opening K2 suddenly changes when the piston 1 moves up and down to suck and discharge the fluid W, the flow state of the fluid W is disturbed and pulsation occurs in the switching valve KV. Causes the problem.

In FIG. 3, first, as a basic curve, the instantaneous suction / discharge amount calculated is shown by a solid line. The instantaneous suction discharge amount is the amount of the fluid W sucked and discharged to the cylinder 2 by moving the piston 1 when the cam C rotates from a predetermined angle by a unit angle. Since the shape of the cam C is circular, the change in the instantaneous suction discharge amount becomes a sine curve.

On the other hand, when the shape of the valve opening K2 is a quadrangular shape (broken line in FIG. 3), the opening area rapidly increases immediately after the valve body V rises and the groove portion 4a and the valve opening K2 start communicating with each other. That is, the fluid W discharged from the cylinder 2 cannot fill the groove portion 4a whose opening area has increased sharply, and the groove portion 4a may have a negative pressure. As a result, the fluid W discharged to the discharge path R2 is pulled back to the groove portion 4a, and pulsation of the fluid W is likely to occur.

When the shape of the valve opening K2 is circular (dashed line in FIG. 3), the change in the opening area is similar to the case of the square cross section. However, at the moment when the groove portion 4a and the valve opening K2 start communicating with each other, the increase in the opening area is smaller than in the case of the square cross section. However, when the groove 4a reaches the position of B1 in FIG. 3, the maximum width of the circular opening communicating with the groove 4a becomes larger than the width of the square opening. Therefore, after this, the degree of increase in the opening area of the circular opening exceeds. That is, in the case of the circular opening, the increase in the instantaneous suction discharge amount is slightly delayed as compared with the case of the square opening, but the tendency is almost the same as a whole. Therefore, even in the case of the circular opening, a negative pressure is likely to be generated in the groove portion 4a of the valve body V at the time of discharge, and pulsation is likely to occur.

On the other hand, the second broken line (broken line longer than the square cross section) in FIG. 3 has a substantially triangular shape of the valve opening K2, and in particular, the valve opening K2 becomes wider as the valve body V moves and the opening area increases. It is configured so that the opening width is wide. The edges on both sides of the valve opening K2 have a curved shape, because this is adapted to the change in the instantaneous discharge amount of the fluid W from the cylinder 2 obtained corresponding to the rising position of the groove portion 4a of the valve body V. Is. According to this opening shape, the tendency of increasing / decreasing the instantaneous suction / discharging amount of the fluid W and the tendency of increasing / decreasing the opening area substantially coincide with each other. It does not occur and the flow velocity of the fluid W is stable. Therefore, it is possible to obtain a fluid pump S with less vibration and noise without oil impact when the switching valve KV is operated.

[Second Embodiment]
FIG. 4 shows a second embodiment of the present invention. Here, an example is shown in which a plurality of plunger unit PUs having both the function of the piston 1 and the function of the switching valve KV are combined to form the fluid pump S. Here, an example in which the four plunger units PU1 to PU4 of the first plunger unit PU1 to the fourth plunger unit PU4 are combined is shown.

For example, the first plunger unit PU1 as a specific plunger unit PU has at least one first opening 21a for sucking and discharging the fluid W once stored and at least one second opening 21b for permitting / blocking the flow of the fluid W. The cylinder 2 provided with the above is provided. The cylinder 2 is the same as the casing K used in the first embodiment. However, in the first embodiment, the portion used as the ventilation hole K1 is the first opening 21a.

Inside the cylinder 2, a piston 1 that reciprocates while forming a fluid chamber 22 is provided. The piston 1 is urged toward the cam C by the spring 3. The piston 1 is provided with a communication passage 4 that communicates with the second opening 21b provided in the wall portion of the cylinder 2 and allows the fluid W to flow in a direction intersecting the direction of reciprocating movement. The communication passage 4 is, for example, the same as the groove portion 4a in the first embodiment.

Further, the first plunger unit PU1 includes a supply path R1 and a discharge path R2 for supplying and discharging the fluid W to and from the fluid chamber 22 through the first opening 21a. As shown in FIG. 4, in these supply passages R1 and discharge passages R2, a single flow path R is connected to the first opening 21a, and the second opening of the second plunger unit PU2 as another plunger unit PU. It is branched and connected to 21b. Further, the supply path R1 and the discharge path R2 of the fourth plunger unit PU4 as another plunger unit PU adjacent to the first plunger unit PU1 are connected to the second opening 21b of the first plunger unit PU1.

Each piston 1 of the four plunger units PU1 to PU4 is operated and controlled by one cam C. Each piston 1 is brought into contact with the cam C with a quarter cycle difference from each other. Thereby, as shown in the first embodiment, the flow rate control of the fluid W can be performed in the communication passage 4 provided in the other piston 1 in accordance with the suction / discharge of the fluid W by one piston 1.

In this way, the supply path R1 and the discharge path R2 related to the four plunger units PU1 to PU4 are connected to each other. Regarding the flow path R of the supply path R1 and the discharge path R2 connected to each cylinder 2 on the opposite side of the flow path R connected to the first opening 21a of the cylinder 2, the supply paths R1 and the discharge path R2 Each of them may be combined into a single flow path R.

As in this configuration, a plurality of plunger unit PUs are provided, and the piston function for sucking and discharging the fluid W and the switching function for switching between the supply path R1 and the discharge path R2 are shared among the different plunger unit PUs, so that the whole can be shared. It is possible to obtain a fluid pump S having a predetermined discharge amount while suppressing the number of parts. In this case, the overall size becomes compact, and a fluid pump S having excellent mountability on a vehicle or the like can be obtained.

Further, by using a plurality of pistons 1 to make a difference in the discharge timing of the fluid W, it is possible to suppress the pulsation of the hydraulic pressure at the time of discharging the fluid W, and it is possible to obtain the fluid pump S with less vibration and noise. can.

[Third Embodiment]
FIG. 5 shows a third embodiment of the present invention. Here, an example in which two sets of the same plunger unit PUs used in the second embodiment are used is shown.

Assuming that the first plunger unit PU1 and the second plunger unit PU2 are used, the first opening 21a of the first plunger unit PU1 and the supply path R1 and the discharge path R2 of the second plunger unit PU2 are connected to each other. Further, the first opening 21a of the second plunger unit PU2 and the supply path R1 and the discharge path R2 of the first plunger unit PU1 are connected to each other.

As described above, by providing two sets of plunger unit PUs, the discharge timing of the fluid W by each piston 1 does not completely cancel each other out, but the pulsation generated from the entire fluid pump S is an example of the first embodiment. It is reduced to some extent compared to. Therefore, even with the fluid pump S having the present configuration, it is possible to obtain the fluid pump S in which the oil intensity and the pulsation of the fluid W at the time of switching the flow path are reduced.

[Other embodiments]
The communication passage 4 provided in the valve body V or the piston 1 shown above may be a through hole extending in a direction intersecting the reciprocating direction of the valve body V instead of the groove portion 4a as described above. The number of through holes is not one, and for example, a through hole for opening and closing the supply path R1 and a through hole for opening and closing the discharge path R2 may be provided separately. In this case, the cylinder 2 is also provided with a valve opening K2 serving as a supply path R1 and a valve opening K2 serving as a discharge path R2 separately. Further, as a configuration in which the instantaneous suction / discharge flow rate is changed according to the movement of the valve body V or the like, at least one of the through hole and the valve opening K2 has a deformed shape, and the through hole and the valve opening K2 overlap. Any configuration can be adopted so that the opening area increases as the degree increases.

The fluid pump according to the present invention can be widely applied to a fluid pump using a plunger and a cam.

1 Piston 2 Cylinder 21 Opening 21a 1st Opening 21b 2nd Opening 22 Fluid Chamber 4 Continuous Passage 4a Groove C Cam K Casing KV Switching Valve PU Plunger Unit R1 Supply Path R2 Discharge Path S Fluid Pump V Valve Body Va Guide Surface W Fluid

Claims (1)

A cylinder provided with at least one first opening for sucking and discharging the fluid once stored and at least one second opening for permitting and blocking the flow of the fluid.
A piston provided with a communication passage that reciprocates while forming a fluid chamber inside the cylinder and that communicates with the second opening and circulates the fluid in a direction intersecting the direction of the reciprocating movement.
A plurality of plunger units having a supply path and a discharge path for supplying and discharging the fluid to and from the fluid chamber through the first opening.
The plurality of plunger units are provided with a cam for driving and controlling the reciprocating motion of each of the pistons so as to be different from each other by a quarter cycle.
The supply path and the discharge path of a specific plunger unit among the plurality of plunger units are connected to the second opening of the other plunger units of the plurality of plunger units.
A fluid pump in which the supply path and the discharge path of the other plunger unit are connected to the second opening of the specific plunger unit.

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