JP2005233103A - Positive-displacement pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a positive-displacement pump which can make a diameter of a cam ring small. <P>SOLUTION: The pump is integrally provided with a pump part 10 and a motor part 12 that drives the pump part 10. A pump housing 14 and a pump rotor 40 are arranged at the pump part 10. The pump housing has the cam ring 15 concentrically, and the pump rotor rotates eccentrically to a cam profile 60 arranged at the inner radius of the cam ring 15. A motor housing 18 and an armature 30 are arranged at the motor part 12. The motor housing is concentric to the pump housing 14, and the armature rotationally drives the pump rotor 40 on the same center of rotation. A fluid discharged from the pump part 10 by the drive of the motor part 12 is discharged outside by way of the interior of the motor part 12. Then the center of rotation 40c of the armature 30 and the pump rotor 40 is made eccentric to the motor housing 18 and the pump housing 14. Then the cam profile 60 is formed concentrically to the cam ring 15. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a positive displacement pump such as a radial piston pump, a vane pump, or a trochoid pump that performs a fluid pumping action using a volume change.

2. Description of the Related Art Conventionally, positive displacement pumps include radial piston pumps that perform a pumping action such as suction and discharge of fluid using a volume change caused by a reciprocating motion of a piston accompanying rotation of a pump rotor.
A conventional example of a radial piston pump will be described. As shown in FIG. 7, the radial piston pump integrally includes a pump unit 110 that sucks and discharges fuel, which is a fluid, and a motor unit 112 that drives the pump unit 110. The pump housing 114 of the pump unit 110 includes a pump housing cylinder 115 and a pump cover 116. The motor housing 118 of the motor unit 112 includes a motor housing cylinder 119 and a motor cover 120. The pump housing cylinder 115 and the motor housing cylinder 119 are connected via a partition wall 122.

In the pump part 110, there is a pump rotor 140 that is rotatably fitted to a pump shaft part 144 provided in the pump housing 114 and is movably fitted to the motor output shaft 131 of the armature 130 of the motor part 112. Is provided.
In a cylinder hole 156 formed in the outer peripheral portion of the pump rotor 140, for example, three spherical pistons 157 are accommodated so as to reciprocate in the radial direction of the pump rotor 140.

The pump housing cylinder 115 also serves as a cam ring, and a cam profile 160 on which the piston 157 moves, slides and / or rolls is formed on the inner peripheral surface thereof. The center 160c of the cam profile 160 is eccentric with respect to the rotation center 140c of the pump rotor 140 (see FIG. 9). The rotation center 140c of the pump rotor 140 is located on the same axis as the pump shaft portion 144 and the motor output shaft 131 (see FIGS. 7 and 8).
Therefore, when the pump rotor 140 is rotated by driving the motor unit 112, the piston 157 urged outward by centrifugal force reciprocates in the cylinder hole 156 of the pump rotor 140 while moving along the cam profile 160. Due to the reciprocation of the piston 157, the volume in the cylinder hole 156 changes. By performing the pumping operation of the fuel using the volume change, the fuel discharged from the pump unit 110 is discharged outside through the motor unit 112.

In addition to the above, for example, there is a radial piston pump described in Patent Documents 1 and 2.
Japanese Patent Laid-Open No. 3-15672 JP-A-6-330848

  According to the above-described radial piston pump (see FIG. 7), the cam ring or pump housing cylinder 115 and the armature 130 are arranged concentrically. At the same time, the cam profile 160 is eccentric with respect to the outer peripheral surface 115a of the pump housing cylinder (cam ring) 115 (see FIG. 9). For this reason, the thickness 115t of the pump housing cylinder (cam ring) 115 must be non-uniform, and there is a problem that the diameter of the cam ring must be increased.

  The problem to be solved by the present invention is to provide a positive displacement pump capable of reducing the diameter of a cam ring.

The above-described problems can be solved by a positive displacement pump having the gist of the configuration described in the claims of the present invention.
That is, according to the positive displacement pump described in claim 1, the rotation center of the motor rotor and the pump rotor is eccentric with respect to the motor housing and the pump portion, and the cam profile is formed concentrically with respect to the cam ring. Has been. For this reason, it is possible to avoid an increase in the diameter of the cam ring due to the eccentricity of the cam profile and to reduce the diameter of the cam ring. This is effective for downsizing the positive displacement pump.

  According to the positive displacement pump described in claim 2 of the claims, the motor part is constituted by a brushless motor, the stator is provided in the motor part, and the magnet is provided in the pump rotor. And the internal space of a pump part and the internal space of a motor part are divided by the partition wall which has a communicating port which connects the discharge passage of a pump rotor, and the internal space of a motor part. Therefore, by partitioning the internal space of the pump part and the internal space of the motor part in pressure, a decrease in pump efficiency due to pressure leakage between the internal spaces can be avoided, and the pump efficiency can be improved.

  According to the positive displacement pump of the present invention, an increase in the diameter of the cam ring due to the eccentricity of the cam profile can be avoided, and the diameter of the cam ring can be reduced. This is effective for downsizing the positive displacement pump.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the following examples.

A positive displacement pump according to Example 1 of the present invention will be described. In this embodiment, a radial piston pump as a positive displacement pump used in a fuel pump that pumps fuel as a fluid is illustrated.
As shown in FIG. 1, the radial piston pump is integrally provided with a pump unit 10 that sucks and discharges fuel and a motor unit 12 that drives the pump unit 10.
The housing 13 that forms the outline of the radial piston pump includes a pump housing 14 that forms the outline of the pump section 10 and a motor housing 18 that forms the outline of the motor section 12. The pump housing 14 includes a substantially cylindrical pump housing cylinder 15 and a pump cover 16 that closes one end face (left end face in FIG. 1). The motor housing 18 includes a substantially cylindrical motor housing cylinder 19 and a motor cover 20 that closes one end face (the right end face in FIG. 1).
The pump housing cylinder 15 and the motor housing cylinder 19 are connected via a partition wall 22. The partition wall 22 partitions the interior of the housing 13 into an internal space 24 of the pump unit 10 and an internal space 26 of the motor unit 12.
Further, the motor cover 20 is formed with a discharge port 27 that allows the internal space 26 of the motor unit 12 to communicate with the outside. Although not shown, the motor cover 20 incorporates a brush that is in sliding contact with a commutator of an armature 30 (described later), a choke coil that is conductively connected to the brush, and the like.

The motor unit 12 is constituted by a well-known DC motor, and is disposed on the inner peripheral surface of the motor housing cylinder 19 and the armature 30 that rotates integrally with the motor output shaft 31 in the internal space 26 of the motor unit 12. A plurality of magnets 32 are provided. The armature 30 corresponds to a “motor rotor” in this specification.
Further, one end portion (right end portion in FIG. 1) of the motor output shaft 31 is rotatably supported by the motor cover 20 via a bearing 37. Further, a pump rotor 40 described later is fitted to the other end portion of the motor output shaft 31 so as to be driven.

The pump unit 10 includes a substantially circular pump rotor 40 that rotates following the motor output shaft 31 in the internal space 24 of the pump unit 10. A substantially bottomed cylindrical fitting hole 41 that opens to the pump cover 16 side and a substantially columnar rotor shaft portion 42 that projects to the opposite side of the shaft center of the pump rotor 40 are on the same axis. Is formed.
A substantially cylindrical pump shaft portion 44 projects from the inner surface of the shaft center portion of the pump cover 16. A fitting hole 41 of the pump rotor 40 is rotatably fitted to the pump shaft portion 44. The protruding end surface 44a of the pump shaft portion 44 and the bottom surface of the fitting hole 41 of the pump rotor 40 are opposed to each other with a predetermined gap.
A rotor shaft portion 42 is rotatably supported by the partition wall 22 via a bearing 48. Further, the rotor shaft portion 42 is formed with a fitting connection hole 42a having an irregular cross section (for example, a D cross section). In the fitting connection hole 42a, a connecting shaft portion 31a having a deformed cross section (for example, a D-shaped cross section) at the left end portion of the motor output shaft 31 is fitted so as to be interlocked.

A suction passage 50 and a discharge passage 52 are formed in the pump shaft portion 44 of the pump cover 16.
One end of the suction passage 50 (the left end in FIG. 1) communicates with the outside. Further, the other end portion (the right end portion in FIG. 1) of the suction passage 50 can communicate with a communication hole 43 formed on the peripheral wall of the fitting hole 41 of the pump rotor 40 and communicating with a cylinder hole 56 (described later). Is formed.
Further, one end portion (left end portion in FIG. 1) of the discharge passage 52 is formed to be able to communicate with the communication hole 43 of the pump rotor 40. Further, the other end portion (the right end portion in FIG. 1) of the discharge passage 52 is opened to the protruding end surface 44 a of the pump shaft portion 44.
A communication passage 54 is formed in the rotor shaft portion 42 of the pump rotor 40. One end portion (left end portion in FIG. 1) of the communication path 54 is open to the bottom surface of the fitting hole 41. Further, the other end portion (the right end portion in FIG. 1) of the communication path 54 is opened to the internal space 26 of the motor portion 12.

  A plurality (two are shown in FIG. 1) of cylindrical cylinder holes 56 extending radially are formed in the outer peripheral portion of the pump rotor 40 in a cylindrical portion equally divided in the circumferential direction. A spherical piston 57 is accommodated in each cylinder hole 56 so as to be reciprocally movable in the radial direction of the pump rotor 40. The cylinder hole 56 communicates with the communication hole 43.

Since the pump housing cylinder 15 also serves as a cam ring, it is also referred to as a cam ring 15. A cam profile 60 on which the piston 57 moves, slides and / or rolls is formed on the inner peripheral surface of the cam ring 15 (see FIG. 3). The cam ring having the cam profile 60 can be provided separately from the pump housing cylinder 15.
The center 60c of the cam profile 60 is eccentric with a predetermined amount x with respect to the rotation center 40c of the pump rotor 40 (see FIGS. 1 and 2). The rotation center 40 c of the pump rotor 40 is located on the same axis 40 c as the pump shaft portion 44 and the motor output shaft 31. As shown in FIG. 3, the cam ring 15 is formed with a uniform wall thickness 15t, and has an outer peripheral surface 15a concentric with the center 60c of the cam profile 60. The pump housing 14 and the motor housing 18 of the housing 13 are formed concentrically with the center 60 c of the cam profile 60.

  Therefore, when the pump rotor 40 rotates, the piston 57 urged outward by the centrifugal force reciprocates in the cylinder hole 56 while moving along the cam profile 60. The reciprocating motion of the piston 57 changes the volume in the cylinder hole 56 (specifically, the cylinder chamber 58 that is a space closed by the piston 57). The pumping action of the fuel is performed using the volume change.

  Thus, the rotation center 40c of the armature 30 and the pump rotor 40 is eccentric with a predetermined amount x with respect to the center of the motor housing 18 and the pump housing 14 of the housing 13 (that is, the center 60c of the cam profile 60). (See FIG. 2). For this reason, the magnet 32 is biased and arranged in a space portion extending in one half (upper half in FIG. 2) of the internal space 26 of the motor portion 12 due to the eccentricity.

Next, the operation of the above-described radial piston pump will be described.
The armature 30 is rotated by driving the motor unit 12. The rotational force of the armature 30 is transmitted from the motor output shaft 31 to the pump rotor 40, and the pump rotor 40 rotates around the pump shaft portion 44 in a predetermined direction. Here, since the rotation center 40c of the pump rotor 40 and the center 60c of the cam profile 60 of the pump housing cylinder 15 are provided eccentrically by a predetermined amount x (see FIG. 1), the piston 57 is rotated by the rotation of the pump rotor 40. The cylinder hole 56 reciprocates.
As the distance between the pump rotor 40 and the cam profile 60 increases, the piston 57 moves outwardly in the cylinder hole 56 (so-called forward movement), so that the volume of the cylinder chamber 58 increases. At this time, the cylinder chamber 58 communicates with the suction passage 50 through the communication hole 43. As a result, a suction stroke is performed in which fuel is sucked into the cylinder chamber 58 from the suction passage 50 through the communication hole 43.
Further, as the distance between the pump rotor 40 and the cam profile 60 decreases, the piston 57 moves to the bottom in the cylinder hole 56 (so-called backward movement), so that the volume of the cylinder chamber 58 decreases. At this time, the cylinder chamber 58 communicates with the discharge passage 52 through the communication hole 43. Thus, a discharge stroke is performed in which the fuel in the cylinder chamber 58 flows out from the communication hole 43 to the internal space 26 of the motor unit 12 through the discharge passage 52 and the communication passage 54. Further, the fuel discharged into the internal space 26 of the motor unit 12 is discharged to the outside through the discharge space 27 of the motor cover 20 via the internal space 26.

  According to the above-described radial piston pump, the rotation center 40 c of the armature 30 and the pump rotor 40 is eccentric with respect to the motor housing 18 and the pump housing 14, and the cam profile 60 is formed concentrically with the cam ring 15. For this reason, the wall thickness 15t of the cam ring 15 can be made uniform, the increase in the diameter of the cam ring 15 due to the eccentricity of the cam profile 60 can be avoided, and the cam ring 15 can be reduced in diameter. This is effective for downsizing the positive displacement pump.

  Further, the centers 60c of the inner and outer diameters of the cam ring 15 coincide with each other, and the wall thickness 15t of the cam ring 15 is made uniform in the circumferential direction (see FIG. 3). For this reason, the moldability of the cam ring 15 can be improved and cost reduction can be realized.

  Further, since the rotation center 40c of the armature 30 is eccentric with respect to the center 60c of the motor housing 18, a wide space portion is formed in one half portion (upper half portion in FIG. 2) of the internal space 26 of the motor portion 12. The Accordingly, the fuel flow resistance in the internal space 26 of the motor unit 12 is widened, so that the flow resistance of the fuel can be reduced.

Meanwhile, in the radial piston pump, the fuel pressure in the internal space 26 of the motor unit 12 is higher than the fuel pressure in the internal space 24 of the pump unit 10. For this reason, pressure leakage from the internal space 26 of the motor unit 12 to the internal space 24 of the pump unit 10 occurs through the clearance between the rotor shaft 42 of the pump rotor 40 and the bearing 48 that supports the rotor shaft 42. May occur. When such pressure leakage occurs, the internal space 24 of the pump unit 10, that is, the space on the outer peripheral side of the pump rotor 40, becomes high pressure, and the forward movement of the piston 57 may be hindered.
Therefore, in such a case, as shown in FIG. 4, the pump cover 16 is provided with a pressure relief hole 16a that opens the internal space 24 of the pump unit 10 to the outside, so that the piston 57 moves forward due to pressure leakage. Can be prevented or reduced.
Alternatively, as shown in FIG. 5, a spring 59 that urges the piston 57 may be added in the cylinder hole 56 of the pump rotor 40.

Next, a radial piston pump according to Example 2 of the present invention will be described. Since this embodiment is obtained by changing a part of the first embodiment, the changed portion will be described in detail, and redundant description will be omitted. In addition, the description which overlaps similarly about the subsequent Examples is also abbreviate | omitted.
That is, in the second embodiment, as shown in FIG. 6, instead of the motor section 12 of the direct current motor of the radial piston pump of the first embodiment (see FIG. 1), a motor section 64 is configured by a brushless motor.
A stator 70 is provided in the internal space 26 of the motor unit 64 of this embodiment. The center of the stator 70 is concentric with the rotation center 40c of the pump rotor 40, and is eccentric with a predetermined amount x with respect to the center 60c of the pump housing 14, the motor housing 18, and the cam profile 60. The motor housing 18 is formed by integrally forming the motor housing cylinder 19 and the motor cover 20 in the first embodiment (see FIG. 1).

Further, instead of the armature 30 in the first embodiment (see FIG. 1), the pump rotor 40 also serves as a motor rotor. A magnet 69 facing the stator 70 is provided on the end surface of the pump rotor 40 on the motor part 64 side.
The pump rotor 40 is formed so as to open the fitting hole 41, and the rotor shaft portion 42 including the communication passage 54 in the first embodiment (see FIG. 1) is omitted.
The internal space 24 of the pump unit 10 and the internal space 26 of the motor unit 64 are partitioned by a partition wall 72. A protruding end surface 44 a of the pump shaft portion 44 of the pump cover 16 penetrating the fitting hole 41 of the pump rotor 40 is brought into contact with the partition wall 72 in a surface contact manner. The partition wall 72 is formed with a communication port 72 a that communicates the discharge passage 52 of the pump rotor 40 and the internal space 26 of the motor unit 12. In this way, the internal space 24 of the pump unit 10 and the internal space 26 of the motor unit 12 are pressure-divided.

Next, the operation of the above-described radial piston pump will be described.
By driving the motor unit 64, the pump rotor 40 having the magnet 69 rotates around the pump shaft unit 44 in a predetermined direction. Thus, similarly to the above, fuel is pumped using the volume change caused by the reciprocating motion of the piston 57, and the fuel discharged from the pump unit 10 passes through the communication port 72 a of the partition wall 72 into the motor unit 64. It is discharged to the outside via.

The same effects as those of the first embodiment can be obtained by the radial piston pump of the second embodiment described above.
In addition, by dividing the internal space 24 of the pump unit 10 and the internal space 26 of the motor unit 12 by the brushless motor by the partition wall 72, the pump efficiency due to pressure leakage between the internal spaces 24 and 26 is improved. A reduction can be avoided and the pump efficiency can be improved.
Specifically, the pump efficiency can be improved by avoiding a decrease in pump efficiency due to pressure leakage when the pressure relief hole 16a described as a modification of the first embodiment is provided (see FIG. 4). Further, the pump efficiency can be improved by avoiding a decrease in pump efficiency due to an increase in sliding resistance of the piston 57 with respect to the cam profile 60 when the spring 59 is provided (see FIG. 5).

  The present invention is not limited to the above-described embodiments, and modifications can be made without departing from the gist of the present invention. For example, the present invention can be applied not only to a radial piston pump but also to a positive displacement pump such as a vane pump, a roller vane pump, or a trochoid pump. The spherical piston 57 can be replaced with a plunger type piston. Further, the number of pistons 57 can be increased or decreased as appropriate. Further, the suction passage 50 and the discharge passage 52 are not limited to a pair in the above-described embodiment, and can be provided as a plurality of pairs. Further, a brushless motor can be employed in place of the motor unit 12 of the DC motor of the first embodiment.

It is sectional drawing which shows the radial piston pump concerning Example 1 of this invention. It is the II-II sectional view taken on the line of FIG. It is an end view of a cam ring. It is sectional drawing which shows the example of a change of a radial piston pump. It is sectional drawing which shows the example of a change of a radial piston pump. It is sectional drawing which shows the radial piston pump concerning Example 2 of this invention. It is sectional drawing which shows the radial piston pump concerning a prior art example. FIG. 8 is a cross-sectional view taken along line VIII-VIII in FIG. 7. It is an end view of a cam ring.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Pump part 12 Motor part 14 Pump housing 15 Cam ring 18 Motor housing 24 Internal space of pump part 26 Internal space of motor part 30 Armature (motor rotor)
32 Magnet 40 Pump rotor 60 Cam profile 64 Motor part 69 Magnet 70 Stator 72 Partition wall 72a Communication port

Claims (2)

A pump part that sucks and discharges fluid and a motor part that drives the pump part are integrally provided,
The pump portion is provided with a pump housing having a concentric cam ring, and a pump rotor that rotates eccentrically with respect to a cam profile provided on the inner periphery of the cam ring,
The motor unit includes a motor housing that is concentric with the pump housing, and a motor rotor that rotationally drives the pump rotor on the same rotation center.
A positive displacement pump in which fluid discharged from the pump unit by driving the motor unit is discharged outside through the motor unit,
The positive displacement pump characterized in that the rotation center of the motor rotor and the pump rotor is eccentric with respect to the motor housing and the pump portion, and the cam profile is formed concentrically with the cam ring. The positive displacement pump according to claim 1,
The motor part is composed of a brushless motor,
The motor unit is provided with a stator of the brushless motor,
The pump rotor is provided with a magnet facing the stator,
The internal space of the pump unit and the internal space of the motor unit are partitioned by a partition wall having a communication port that communicates the discharge passage of the pump rotor and the internal space of the motor unit. Type pump.

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