JP5744155B2 - Electric pump - Google Patents

Description

  The present invention relates to an electric pump.

  2. Description of the Related Art Conventionally, there is an electric pump that causes fluid to flow into a discharge passage through a suction passage and a pressure increasing chamber as the piston reciprocates. In recent years, electric pumps are used, for example, in idle stop systems. This idle stop system is being adopted as a technology that can be expected to improve fuel efficiency and reduce exhaust gas relatively easily, while improving fuel economy and exhaust gas regulations for automobiles, etc. This is a system that stops the engine when traveling and restarts the engine when restarting. In this idle stop system, the electric pump is used to reduce the starting shock immediately after the engine restart, to generate pressure in the transmission during idle stop, or to fill the transmission with oil. .

  The electric pump sucks fluid from the suction passage and pumps it to the discharge passage by the reciprocating movement of the piston. If the discharge flow rate of the electric pump is larger than the required flow rate on the transmission side, or the volume of the transmission suddenly increases. When fluctuations occur, the discharge pressure may become extremely large. For this reason, in the electric pump, a relief valve for relief of fluid from the discharge passage (high pressure side) to the low pressure side is provided in order to prevent an unexpected load from being generated in the pump functional parts (for example, Patent Document 1).

JP 2010-14012 A

  By the way, in the relief valve as described above, when the passage flow rate to the relief valve becomes large or accompanied by a sudden change in the flow rate, the lift of the valve body becomes unstable, abnormal noise (oscillation), etc. May occur. Further, when this oscillation phenomenon continues, there is a concern that the reliability (durability) of the relief valve is deteriorated.

  The present invention has been made in view of the above, and provides an electric pump including a relief valve that can prevent generation of abnormal noise (oscillation) and the like and can improve reliability (durability). For the purpose.

  The present invention for achieving the above-described object includes a pump unit and a motor unit that operates the pump unit. The pump unit includes a plurality of pistons and a plurality of cylinder chambers that accommodate the plurality of pistons. And an swash plate that is driven by the motor unit to reciprocate the pistons, and the pump unit has a constant pressure on the discharge side of the electric pump. A relief valve is provided for opening the valve when the pressure exceeds the pressure and relieving the fluid discharged from the cylinder chamber, and the cylinder has a relief path for relieving the fluid discharged from the cylinder chamber, and the relief valve Is provided in the relief path, and includes a valve seat, a valve body selectively seated on the valve seat, and a spring hob with one end connected to the valve body. And a cap having one end supported by the spring holder, and a cap for supporting the other end of the spring and inserting the other end of the spring holder to guide the movement of the spring holder, The clearance in the radial direction between the central portion in the axial direction of the spring and the portion defining the relief path in the cylinder is defined as a clearance w1, and the one end of the spring holder and the relief path in the cylinder. The clearance in the radial direction between the portions defining the clearance is defined as a clearance w2, and the radial spacing between the axial end of the spring and the portion defining the relief path in the cylinder Is the clearance w3, the clearance w1 is smaller than the clearance w2, and the clearer Smaller than both of the scan w3.

  According to the present invention, it is possible to prevent abnormal noise (oscillation) and the like and improve reliability (durability).

It is sectional drawing which shows the inside of the piston pump which concerns on Embodiment 1 of this invention. It is a figure which shows the state of the relief valve in the suction process regarding this Embodiment 1. FIG. It is a figure which shows the state of the relief valve in the discharge process regarding this Embodiment 1. FIG. It is a figure which shows the state at the time of valve opening of the relief valve regarding this Embodiment 1. FIG. It is a figure which shows the structure of the relief valve of the piston pump which concerns on Embodiment 2 of this invention. It is a figure which shows the structure of the relief valve of the piston pump which concerns on Embodiment 3 of this invention.

  DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment in which an electric pump according to the present invention is implemented as a piston pump used in an automobile idle stop system will be described with reference to the accompanying drawings. In the drawings, the same reference numerals indicate the same or corresponding parts.

Embodiment 1 FIG.
FIG. 1 is a cross-sectional view showing the inside of the piston pump according to the first embodiment. The piston pump shown in FIG. 1 is used to generate pressure in the transmission during idle stop or to fill the transmission with oil in an idle stop system in order to reduce start shock immediately after engine restart. Used for.

  The piston pump 100 includes a pump unit 1 and a motor unit 2 that operates the pump unit 1. The pump unit 1 has a pump case 5 in which a suction passage 3 and a discharge passage 4 are formed.

  A cylinder 6 is accommodated in the pump case 5, and a plurality of cylinder chambers (sliding holes) 6 a are formed in the cylinder 6. The plurality of cylinder chambers 6a are arranged at an equiangular pitch in the circumferential direction, and are arranged on a line that forms a ring around the rotation axis of the piston pump 100 (rotation axis of the rotor 16 described later). A corresponding piston 7 is arranged in each of the plurality of cylinder chambers 6a.

  In addition, the pump unit 1 is provided with a suction valve 8, a valve plate 9, and a discharge valve 10. The suction valve 8 is in surface contact with the cylinder 6 and seals so that the fluid sucked by the reciprocating motion of the piston 7 does not flow backward. The valve plate 9 constitutes a passage that connects the pressure increasing chamber and the suction passage 3 / discharge passage 4. Further, the discharge valve 10 is in surface contact with the valve plate 9 and seals so that the discharged fluid does not flow backward.

  The motor unit 2 has a resin motor case 12 connected to the pump case 5 via a seal member 11. A stator 13 around which a coil is wound is fixed inside the motor case 12, and a rotor 16 rotatably supported by bearings 14 and 15 is provided inside the stator 13. . The rotor 16 has a shaft 16a fitted to the bearings 14 and 15, and a ring-shaped permanent magnet 17 fixed to the shaft 16a by, for example, resin molding. Further, a swash plate 19 is provided on the shaft 16 a via a bearing 18.

  Further, a motor drive driver 20 is provided on the motor case 12 on the side opposite to the pump unit 1, and the electric power supplied from the outside is coiled in the stator 13 via the driver 20. To be supplied. Thus, when a rotating magnetic field is applied to the coil, the rotor 16 is rotated by the action of the permanent magnet 17. In the pump unit 1, the inclination of the swash plate 19 is changed by the rotational movement of the shaft 16 a, and each piston 7 reciprocates. With this reciprocating motion, fluid enters from the suction passage 3 and is discharged from the discharge passage 4.

  Next, the relief valve 101 provided in the pump unit 1 will be described. The relief valve 101 is provided in the cylinder 6 in the pump unit 1, and more specifically, is disposed in a relief path 6 b formed in the cylinder 6. The relief path 6b is formed inside the plurality of cylinder chambers 6a (inside in the radial direction around the rotation axis of the rotor 16), in other words, on the extension of the shaft 16a of the rotor 16 (on the rotation axis of the rotor 16). ). The relief valve 101 includes a valve seat 21, a valve body 22, a spring holder 23, a spring 24, and a cap 25.

  The valve seat 21 is disposed in a relief passage 6b that communicates the suction passage 3 (low pressure side) and the discharge passage 4 (high pressure side) formed in the cylinder 6, and has a fluid circulation hole. The valve seat 21 is fixed in the relief path 6b, for example, by press fitting.

  The valve body 22 is selectively seated on the valve seat 21 and selectively closes / opens the fluid flow hole of the valve seat 21. The valve body 22 is comprised with the steel ball, for example.

  The spring holder 23 and the spring 24 are disposed on the opposite side of the valve seat 21 with respect to the valve body 22 in the relief path 6b. One end of the spring holder 23 is connected to the valve body 22. The other end of the spring holder 23 is supported by a cap 25 provided in the relief path 6b. More specifically, the spring holder 23 is supported by the cap 25 so as to be movable in the extending direction of the relief path 6b (the axial direction of the relief valve 101 / the approaching / separating direction with respect to the valve body 22). The other end of the spring holder 23 is slidably inserted into the cap 25, and the cap 25 guides the movement of the relief path 6 b in the extension direction of the spring holder 23. Further, a plurality of protrusions 23a (for example, three locations in this example) are provided on the outer peripheral portion of the spring holder 23 at an equiangular pitch for guiding the lift of the spring holder 23, for example. In the partially enlarged portion of FIG. 1, a cross section of a portion where the projection 23a is not present on the upper side of the spring holder 23 on the paper surface of FIG. A cross section appears. The cap 25 is fixed in the relief path 6b by, for example, press fitting or caulking.

  The spring 24 is disposed between the spring holder 23 and the cap 25, and one end of the spring 24 is connected to the spring holder 23, and the other end of the spring 24 is connected to the cap 25. As a result, the valve body 22 is always urged in the direction of seating with the valve seat 21 by the elastic force of the spring 24. The spring 24 determines a load for bringing the valve body 22 into contact with the valve seat 21, that is, sets a pressure for closing the relief valve 101.

  As shown in the partially enlarged portion of FIG. 1, the spring 24 has a shape in which the diameter changes in a barrel shape (the diameter is not constant) when viewed from the direction orthogonal to the axial direction. . That is, the diameter of the central portion in the axial center direction of the spring 24 is the largest, and the diameter of the spring 24 changes so as to become smaller as the portion is away from the central portion in the axial center direction in the axial direction. Here, the radial interval between the axial center portion of the spring 24 and the portion 6d defining the relief path 6b in the cylinder 6 is defined as a clearance w1, and the protrusion 23a of the spring holder 23 and the cylinder The radial distance between the portion 6d defining the relief path 6b in 6 is the clearance w2, the axial end of the spring 24, and the portion 6d defining the relief path 6b in the cylinder 6 The clearance w3 is smaller than the clearance w2 and smaller than the clearance w3. In other words, the spring 24 is formed in a barrel shape so as to satisfy the relationship between the clearances w1, w2, and w3, and the spring 24 and the portion 6d that defines the relief path 6b, The positional relationship with the protrusion 23a is designed and adjusted.

  In addition, it can be said that the relief valve 101 is directly accommodated in the relief path 6 b formed by only the cylinder 6. In other words, the valve seat 21, the valve body 22, the spring holder 23, and the spring 24 are all directly accommodated in the relief path 6b, that is, directly accommodated only in the cylinder 6.

  Next, the operation of the relief valve 101 will be described with reference to FIGS. FIG. 2 is a diagram illustrating a state of the relief valve in the suction process, and FIG. 3 is a diagram illustrating a state of the relief valve in the discharge process. FIG. 4 is a view showing the opened state of the relief valve. In addition, the arrow shown in FIGS. 2-4 shows the flow of a fluid.

  At the time of normal intake / exhaust when the relief valve 101 is closed, as shown in FIG. 2, when the cylinder chamber 6a expands due to the movement of the piston 7, the fluid passes through the intake valve 8 which is opened, and the cylinder Inhaled into the room. Subsequently, as shown in FIG. 3, when the cylinder chamber shrinks due to the movement of the piston 7, the fluid is pushed out of the cylinder chamber 6 a and passes through the opened discharge valve 10 to the discharge passage 4. Discharged.

  On the other hand, when the pressure on the discharge side exceeds a certain pressure and the load acting on the pump functional parts is likely to be excessive, the fluid to be discharged from the cylinder chamber 6a to the discharge passage 4 as follows. At least a part of is relieved.

  That is, one end side of the bypass path 4a communicates with the path from the cylinder chamber 6a to the discharge path 4, and the other end side of the bypass path 4a communicates with the relief path 6b (the flow hole of the valve seat 21). ing. Therefore, the pressure downstream of the discharge valve 10 in the discharge passage 4 always acts on the valve body 22 via the bypass passage 4a. Therefore, when the pressure on the discharge side acting on the valve body 22 exceeds a certain pressure, the pressure on the discharge side acting on the valve body 22 overcomes the valve closing force by the spring 24 and is shown in FIG. As a result, the valve body 22 is opened. Thereby, at least a part of the fluid to be discharged from the cylinder chamber 6a to the discharge passage 4 is relieved in the relief passage 6b through the bypass passage 4a. It is assumed that the spring holder 23 and the cap 25 are provided with a through hole or a clearance forming portion (a clearance generated between the defining surface of the relief path 6b) for relieving the fluid.

  Further, when an excessive flow rate flows through the relief valve 101 or when a sudden flow rate change occurs, the lift of the valve body 22 increases or the position of the valve body 22 changes abruptly. It may become unstable and lead to abnormal noise (oscillation). On the other hand, in the piston pump according to the first embodiment, since the spring 24 has a barrel shape, when the valve body 22 tries to behave in an unstable manner, the central portion in the axial center direction of the spring 24 is , Guided to the portion 6d defining the relief path 6b. That is, when the valve body 22 is likely to fall into an unstable behavior due to the relationship of the clearance w1 <clearance w2 and w3, the spring 24 and the spring 24 have an axial center end before the end of the spring 24. The central portion in the axial direction can be guided by the portion 6d that defines the relief path 6b. In addition, since the central portion in the axial direction of the spring 24 is to be guided, the guide action can be obtained more reliably than in the case where the axial end portion of the spring 24 is to be guided. Thus, the guide action to the spring holder 23 via the spring 24 and the portion 6d can suppress the unstable behavior of the valve body 22 and prevent the above abnormal noise (oscillation) and the like.

  Further, when the pressure on the discharge side is less than a certain pressure, that is, during normal intake / exhaust, the valve body 22 contacts the valve seat 21 by the action of the spring 24 as shown in FIGS. The distribution hole is sealed.

  In the piston pump according to the first embodiment configured as described above, the central portion of the spring is guided by the portion defining the relief path in the cylinder, so that an excessive flow rate flows through the relief valve. Even when the flow rate changes suddenly, the phenomenon that the behavior of the valve element becomes unstable can be suppressed, and abnormal noise (oscillation) or the like can be prevented. Further, by suppressing the unstable behavior of the valve body, it is possible to prevent the unexpected part from abutting or sliding in the relief valve component, and the durability of the relief valve component to be significantly reduced.

  In addition, in the first embodiment, not only the increase in the number of parts and man-hours can be suppressed, but also the relief valve is directly accommodated in the relief path formed in the cylinder having the cylinder chamber. (In the first embodiment, the valve seat, the valve body, the spring holder, and the spring) are assembled in advance (sub-assembly process) with different elements different from the cylinder, and the assembled relief valve is further incorporated in the pump. It will end. That is, since the sub-assembly process can be omitted, an increase in the number of parts associated with the relief valve installation can be suppressed, an increase in processing man-hours and an increase in assembly man-hours can be suppressed, and cost can be reduced. it can. Therefore, according to the piston pump of the first embodiment, it is possible to protect the pump functional parts against overload while suppressing the increase in the number of parts and the increase in the man-hours.

  Further, in the piston pump of the first embodiment that can suppress the increase in the number of parts and the man-hour as described above, the lift of the valve body is guided only by the sliding portion of the spring holder and the cap, so that the relief Although it can be said that the generation of abnormal noise or the like is more likely to occur when the valve passage flow rate increases or when there is a sudden flow rate change, as described above, in the first embodiment, the relief path in the cylinder Instability of the behavior of the valve body can be suppressed by guiding the central portion of the spring by the portion that defines. In other words, according to the first embodiment, the increase in the number of parts associated with the installation of the relief valve can be minimized, the occurrence of abnormal noise (oscillation), etc. can be prevented, and the reliability (durability) can be improved. Can be planned.

  In order to obtain the advantages as described above, the relief valve is directly accommodated in the cylinder. However, the relief valve is arranged in a vacant space inside the cylinder inside the plurality of cylinder chambers via a relief path. A relief valve is added. For this reason, this embodiment can be carried out without changing the product size by utilizing the empty space inside the cylinder, avoiding the enlargement of the product and the large-scale redesign of the cylinder, and relatively easily. The function of the relief valve can be obtained. Also, the cost can be reduced by such an action.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 5 is a view showing the structure of the relief valve of the piston pump according to Embodiment 2 of the present invention. The second embodiment is the same as the first embodiment described above except for the parts described below.

  The relief valve 201 in the second embodiment has a spring 224 in which the maximum diameter portion 224a is spread over a predetermined range over the axial direction. The maximum diameter portion 224a of the spring 224 includes the central portion in the axial direction of the spring 224, and the range of the maximum diameter portion 224a is on both sides in the axial direction with respect to the central portion in the axial direction of the spring 224. Exists.

  Further, as described in the first embodiment, when viewed from the direction orthogonal to the axial direction, the spring 224 has a portion (maximum diameter portion 224a) swelled outward in the radial direction in the barrel shape. It is formed in a straight shape so as to extend along the direction (along the portion 6d defining the relief path 6b). The diameter of the spring 24 is changed so as to become smaller as it is away from the straight-shaped maximum diameter portion 224a in the axial direction.

  As in the case of the first embodiment, the clearance in the radial direction between the axial center portion of the spring 224 and the portion 6d defining the relief path 6b in the cylinder 6 is defined as a clearance w1, and the spring holder The radial distance between the projection 23a of the cylinder 23 and the portion 6d defining the relief path 6b in the cylinder 6 is defined as a clearance w2, and the axial end of the spring 224 and the relief path 6b in the cylinder 6 Is the clearance w3, the clearance w1 is smaller than the clearance w2 and smaller than the clearance w3.

  The piston pump according to the second embodiment configured as described above also has the same advantages as those of the first embodiment described above. In addition, since the outermost diameter part of the spring is straight, the unstable behavior of the valve body that can occur when an excessive flow rate flows through the leaf valve or a sudden flow rate change occurs is significantly suppressed. It becomes possible to do.

Embodiment 3 FIG.
Next, Embodiment 3 of the present invention will be described with reference to FIG. FIG. 6 is a view showing the structure of the relief valve of the piston pump according to Embodiment 3 of the present invention. In addition, this Embodiment 3 shall be the same as that of Embodiment 1 mentioned above except the part demonstrated below.

  The relief valve 301 is disposed in a relief path 6 c formed in the cylinder 6 in the pump unit 1. The relief path 6c is formed inside the plurality of cylinder chambers 6a (inside in the radial direction around the rotation axis of the rotor 16), in other words, on the extension of the shaft 16a of the rotor 16 (on the rotation axis of the rotor 16). ). The relief valve 301 includes a valve seat 21, a valve body 22, a spring holder 23, a spring 324, and a cap 25.

  In the third embodiment, in the cylinder 6, the convex portion 6 d ′ is provided in a portion 6 d that defines the relief path 6 c. The convex portion 6d ′ protrudes toward the spring 324 disposed in the relief path 6c, and is opposed to the axially central portion when the spring 324 disposed in the relief path 6c is closed. (It is formed near the center of the set length of the spring 324). The projecting tip of the convex portion 6d 'extends over a predetermined range over the axial direction. In other words, when viewed from a direction orthogonal to the axial direction, the protruding tip of the convex portion 6d ′ is formed to have a straight shape so as to extend along the axial direction (along the spring 324). Yes.

  In the third embodiment, the spring 324 has a shape with a constant diameter.

  Further, similarly to the case described in the first embodiment, the clearance in the radial direction between the central portion in the axial center direction of the spring 324 and the portion 6d ′ that defines the relief path 6c in the cylinder 6 is defined as a clearance w1. The radial distance between the protrusion 23a of the spring holder 23 and the portion 6d defining the relief path 6c in the cylinder 6 is defined as a clearance w2, and the axial end of the spring 324 and the cylinder 6 When the radial distance between the relief path 6c and the portion 6d defining the relief path 6c is defined as a clearance w3, the clearance w1 is smaller than the clearance w2 and smaller than the clearance w3.

  The piston pump according to the third embodiment configured as described above has the same advantages as those of the second embodiment described above.

  Although the contents of the present invention have been specifically described with reference to the preferred embodiments, various modifications can be made by those skilled in the art based on the basic technical idea and teachings of the present invention. It is self-explanatory.

  DESCRIPTION OF SYMBOLS 1 Pump part, 2 motor part, 6 cylinder, 6a Cylinder chamber, 6b, 6c Relief path, 6d Relief path demarcated part, 6d 'convex shape part, 7 Piston, 19 Swash plate, 21 Valve seat, 22 Valve Body, 23 spring holder, 24, 224, 324 spring, 25 cap, 100 piston pump, 101, 201, 301 relief valve.

Claims (5)

A pump unit, and a motor unit for operating the pump unit,
The pump unit is provided with a plurality of pistons, a cylinder having a plurality of cylinder chambers that accommodate the plurality of pistons, and a swash plate that is driven by the motor unit to reciprocate the pistons, respectively. An electric pump,
The pump portion is provided with a relief valve that opens when the pressure on the discharge side of the electric pump is equal to or higher than a certain pressure and relieves the fluid discharged from the cylinder chamber,
The cylinder has a relief path for relief of fluid discharged from the cylinder chamber;
The relief valve is provided in the relief path, and includes a valve seat, a valve body selectively seated on the valve seat, a spring holder having one end connected to the valve body, and one end being the spring holder a spring supported by the, co and you support the other end of the spring, the other end of the spring holder is inserted and a cap for guiding the movement of the spring holder,
The clearance in the radial direction between the central portion in the axial direction of the spring and the portion defining the relief path in the cylinder is defined as a clearance w1, and the one end of the spring holder and the relief path in the cylinder. The clearance in the radial direction between the portions defining the clearance is defined as a clearance w2, and the radial spacing between the axial end of the spring and the portion defining the relief path in the cylinder Is the clearance w3, the clearance w1 is smaller than the clearance w2 and smaller than the clearance w3.
Electric pump. The diameter of the spring is the largest in the central portion in the axial direction of the spring, and the smaller the portion away from the central portion in the axial direction in the axial direction,
The electric pump according to claim 1. The maximum diameter portion of the spring extends in the axial direction of the spring, and the maximum diameter portion of the spring includes a central portion in the axial direction of the spring.
The electric pump according to claim 1. The portion defining the relief path is provided with a convex portion,
The convex portion protrudes toward the spring disposed in the relief path, and is formed at a position facing a central portion in the axial direction when the spring disposed in the relief path is closed. Being
The electric pump according to claim 1. The valve seat, the valve body, the spring holder, the spring and the cap are all stored directly in the relief path.
The electric pump according to any one of claims 1 to 4.

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