JPWO2013114813A1 - Pump device - Google Patents

Abstract

A pump device having excellent durability is provided. In a pump device according to an embodiment of the present invention, an eccentric shaft 232 that converts rotation of a drive shaft 131 of a motor M into reciprocating movement of a piston 21 has a hollow structure. By making the eccentric shaft 232 have a hollow structure, the eccentric shaft 232 can be easily deformed in the axial direction (radial direction), and the press-fitting load of the bearing 31 on the outer peripheral surface of the eccentric shaft 232 can be reduced. . As a result, the variation in the internal radial gap of the bearing 31 can be reduced, the uniformity of stress over the entire circumference of the bearing can be increased, the durability of the bearing 31 can be increased, and the life of the pump device 1 can be improved. [Selection] Figure 2

Description

  The present invention relates to a pump device that sucks and exhausts a pump chamber by reciprocating movement of a piston.

  An oscillating piston pump, which is a kind of vacuum pump, is known as a reciprocating pump that alternately performs intake and exhaust of air in a pump chamber by reciprocating a piston in a cylinder. Widely used as a pump.

  This type of pump is press-fitted into the motor, an eccentric shaft arranged eccentrically with respect to the rotation center of the drive shaft of the motor, a connecting rod connected to the piston, and an outer peripheral surface of the eccentric shaft. And a bearing that rotatably connects the eccentric shaft to the connecting rod, and is configured to convert the revolving motion of the eccentric shaft around the drive shaft into a reciprocating movement of the piston (see, for example, Patent Document 1 below) ).

JP 2002-364543 A

  However, since the conventional eccentric shaft has a solid structure, the press-fitting load of the bearing to the outer peripheral portion of the eccentric shaft is large, and it is difficult to mount the bearing with uniform stress in the circumferential direction. As a result, after the press-fitting of the bearing, the variation in the internal radial gap of the bearing (the gap between the outer ring and the inner ring) becomes large, and it is not easy to equalize the stress over the entire circumference. Therefore, the bearing is always subjected to a fluctuating load during the pump operation, which causes a problem that the durability of the bearing is lowered and the life of the pump is also reduced.

  In view of the circumstances as described above, an object of the present invention is to provide a pump device having excellent durability.

In order to achieve the above object, a pump device according to an aspect of the present invention includes a piston, a pump case, a motor, an eccentric member, a rod member, and a first bearing.
The pump case has a cylinder that houses the piston.
The motor has a drive shaft and is fixed to the pump case.
The eccentric member has a hollow eccentric shaft that is connected to the drive shaft and formed eccentric to the rotation center of the drive shaft.
The rod member has a first end connected to the piston, and a second end formed with a fitting hole for fitting with the eccentric shaft, and rotates the drive shaft. It converts into the reciprocating movement of the piston inside the cylinder.
The first bearing is mounted between the eccentric shaft and the fitting hole and rotatably supports the eccentric shaft with respect to the rod member.

It is a perspective view showing the whole pumping device concerning one embodiment of the present invention. It is a longitudinal cross-sectional view of the principal part of the said pump apparatus. It is a longitudinal cross-sectional view which shows the connection relation with the connecting rod and eccentric member of the said pump apparatus. It is a perspective view which shows the connection relation with the connecting rod and eccentric member of the said pump apparatus. It is a front view of the eccentric member. It is a longitudinal cross-sectional view of the said eccentric member. It is a perspective view of the said eccentric member. It is a perspective view of the eccentric member which concerns on a comparative example. It is one experimental result which shows the bearing characteristic of the pump apparatus provided with the eccentric member of this embodiment.

A pump device according to an embodiment of the present invention includes a piston, a pump case, a motor, an eccentric member, a rod member, and a first bearing.
The pump case has a cylinder that houses the piston.
The motor has a drive shaft and is fixed to the pump case.
The eccentric member has a hollow eccentric shaft that is connected to the drive shaft and formed eccentric to the rotation center of the drive shaft.
The rod member has a first end connected to the piston, and a second end formed with a fitting hole for fitting with the eccentric shaft, and rotates the drive shaft. It converts into the reciprocating movement of the piston inside the cylinder.
The first bearing is mounted between the eccentric shaft and the fitting hole and rotatably supports the eccentric shaft with respect to the rod member.

  In the pump device, since the eccentric shaft has a hollow structure, the eccentric shaft is easily deformed in the axial direction (radial direction), and the press-fit load of the first bearing on the outer peripheral surface of the eccentric shaft is reduced. be able to. Thereby, the variation of the internal radial gap of the first bearing can be reduced, and the uniformity of stress over the entire circumference of the bearing can be improved. Therefore, according to the said pump apparatus, durability of a 1st bearing can be improved and the lifetime of a pump apparatus can be improved.

The eccentric member may further include a base block having a first surface on which a connecting hole connected to the drive shaft is formed and a second surface on which the eccentric shaft is formed. .
Thereby, the assembly workability of the drive shaft and the rod member can be improved, and the length of the drive shaft of the motor can be shortened.

The pump device having the above-described configuration may further include a second bearing fixed to the pump case and rotatably supporting the drive shaft.
As described above, as a result of shortening the drive shaft of the motor, the load applied to the second bearing member that supports the drive shaft is reduced, and thereby the life of the pump device can be further improved.

The eccentric member may be formed of a sintered body.
Thereby, it is possible to stably obtain an eccentric member having excellent shape accuracy and having necessary mechanical strength.

The pump device may further include a counterweight attached to the eccentric member and rotating together with the eccentric member.
Thereby, generation | occurrence | production of the vibration by rotation of a motor can be suppressed, and the stable intake / exhaust operation | movement of a pump apparatus can be ensured.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an overall perspective view showing a pump device according to an embodiment of the present invention.

  The pump device 1 of the present embodiment includes a first pump unit 11, a second pump unit 12, and a driving unit 13 that drives the first pump unit 11 and the second pump unit 12 in common.

  The first pump unit 11 is configured as a pressure pump (pressure pump), and the second pump unit 12 is configured as a vacuum pump. However, both the pump units 11 and 12 may be configured as vacuum pumps, You may comprise as a pressurization pump (pressure | voltage rise pump). The pump device 1 is used, for example, as a gas pressure booster in a fuel cell system.

  The first and second pump portions 11 and 12 typically have a common configuration, and in this embodiment, are configured as a swinging piston pump. In addition, the first and second pump units 11 and 12 may be configured as other reciprocating pumps such as a diaphragm pump.

  The pump device 1 includes a first casing 101 that constitutes a part of the first pump unit 11, a second casing 102 that constitutes a part of the second pump unit 12, and a part of the drive unit 13. A pump case 100 including a third casing 103 is provided.

  FIG. 2 is a vertical cross-sectional view showing a partial configuration of the first pump unit 11 and the drive unit 13. In FIG. 2, an X axis, a Y axis, and a Z axis indicate three axial directions that are orthogonal to each other. In addition, since the 2nd pump part 12 is comprised similarly to the 1st pump part 11, the 1st pump part 11 is mainly demonstrated here.

  The first pump unit 11 includes a first casing 101, a piston 21, a connecting rod 22 (rod member), and an eccentric member 23.

  The first casing 101 includes a case main body 110, a cylinder 111, a pump head 112, and a pump head cover 113. The case body 110, the cylinder 111, the pump head 112, and the pump head cover 113 are integrated with each other so as to be stacked in the Z-axis direction.

  The case main body 110 is connected to the third casing 103 that houses the motor M, and has a through hole 110h through which the connecting rod 22 passes. The case main body 110 includes a fixed portion 110 a that fixes a bearing 32 (second bearing) that rotatably supports the drive shaft 131 of the motor M, and a cylindrical portion 110 b that accommodates the coil 132 of the motor M. The bearing 32 is disposed between the main body of the motor M and the eccentric member 23.

  The cylinder 111 is disposed between the case main body 110 and the pump head 112, and accommodates the piston 21 slidably in the Z-axis direction. The pump head 112 is disposed between the cylinder 111 and the pump head cover 113, and includes an intake valve 112a and an exhaust valve 112b. The pump head cover 113 is disposed on the pump head 112 and has an intake chamber 113a that communicates with the intake port 114a and an exhaust chamber 113b that communicates with the exhaust port 114b. As shown in FIG. 1, the intake port 114 a and the exhaust port 114 b are provided on the side surfaces of the pump portions 11 and 12 that face each other.

  The piston 21 has a disk shape, and is fixed to the first end 221 of the connecting rod 22 via a screw member 25. The piston 21 forms a pump chamber 26 between the piston 21 and the pump head 112. The piston 21 reciprocates in the direction parallel to the Z-axis direction inside the cylinder 111 and alternately sucks and exhausts the pump chamber 26 via the intake valve 112a and the exhaust valve 11b, thereby performing a predetermined pump action. Do.

  3 and 4 are a longitudinal sectional view and a perspective view showing a connection state between the connecting rod 22 and the eccentric member 23. FIG.

  The connecting rod 22 connects the piston 21 and the eccentric member 23 to each other. The connecting rod 22 has a first end 221 connected to the piston 21 and a second end 222 connected to the eccentric member 23. The first end 221 is formed in a circular shape having substantially the same diameter as the piston 21. A disc-shaped seal member 24 is attached between the piston 21 and the first end 221. The peripheral portion of the seal member 24 is bent toward the pump chamber 26 so as to be slidable on the inner peripheral surface of the cylinder 111.

  In the second pump unit configured as a vacuum pump, the peripheral edge of the seal member is bent to the side opposite to the pump chamber side.

  A fitting hole 222 a that fits the eccentric shaft 232 of the eccentric member 23 is formed in the second end portion 222 of the connecting rod 22. A bearing 31 (first bearing) that rotatably supports the eccentric shaft 232 is mounted in the fitting hole 222a.

  5 is a front view of the eccentric member 23 viewed from the Y-axis direction, FIG. 6 is a cross-sectional view taken along the line AA in FIG. 5, and FIG. 7 is a perspective view of the eccentric member 23.

  The eccentric member 23 connects the drive shaft 131 of the motor M housed in the third casing 103 and the connecting rod 22 to each other. The base block 230 has a substantially cylindrical base block 230.

  The base block 230 has a first surface 230a in which a connection hole 231 connected to the drive shaft 131 is formed, and a second surface 230b in which an eccentric shaft 232 is formed. The eccentric member 23 is formed integrally with the eccentric shaft 232, and in the present embodiment, is constituted by a sintered body of metal powder, ceramic powder, or a mixed powder thereof. In this embodiment, the base block 230 uses an iron-based material as a powder material.

  The connection hole 231 is a circular bottomed hole formed at the center of the first surface 230 a of the base block 230. The drive shaft 131 is inserted into the connection hole 231 along the Y-axis direction, and is connected to the connection hole 231 by a fixing screw 41 that is screwed into a first screw hole H1 formed on the side peripheral surface of the base block 230. .

  The eccentric shaft 232 is formed on the second surface 230b of the base block 230 so as to be eccentric with respect to the rotation center of the drive shaft 131 (center of the eccentric member 23). The eccentric shaft 232 has a cylindrical shape having a hollow portion 232a. The thickness of the eccentric shaft 232 is appropriately set according to the type of pump, the size of the load, etc., and the ratio of the thickness to the outer diameter of the eccentric shaft 232 is, for example, 0.1 to 0.2. .

  The bearing 31 is mounted between the eccentric shaft 232 and the fitting hole 222 a of the connecting rod 22, and supports the eccentric shaft 232 to be rotatable with respect to the connecting rod 22. The bearings 31 and 32 are constituted by an annular ball bearing having an inner ring (inner race), an outer ring (outer race), and a plurality of rolling elements (spheres) enclosed between them. With respect to the bearing 31, the inner ring 31a is fixed to the outer peripheral surface of the eccentric shaft 232 by press-fitting, and the outer ring 31b is fixed to the inner peripheral surface of the fitting hole 222a by press-fitting, and a plurality of spaces are provided between the inner ring 31a and the outer ring 31b. The rolling element 31c is accommodated.

  The first pump unit 11 further includes a counterweight 50. The counterweight 50 is fixed to the side peripheral portion of the eccentric member 23 by a fixing screw 42 that is screwed into a second screw hole H2 formed on the side peripheral surface of the base block 230. The counterweight 50 is for canceling vibration generated when the connecting rod 22 rotates about the eccentric shaft 232 due to the rotation of the drive shaft 131. Is arranged at a position biased in the opposite direction.

  The second pump unit 12 is configured in the same manner as the first pump unit 11. The second pump unit 12 is driven by a common motor M simultaneously with the first pump unit 11. The drive shaft 131 extends to the second pump unit 12 side and is connected to an eccentric shaft (not shown) of the second pump unit 12. In the present embodiment, the first pump unit 11 and the second pump unit 12 are driven with different phases. For example, the eccentric shafts of the pump parts 11 and 12 are set so that the piston of the second pump part 12 is located at the bottom dead center when the piston 21 of the first pump part 11 is located at the top dead center. Is done.

  Next, operation | movement of the pump apparatus 1 of this embodiment comprised as mentioned above is demonstrated. Here, the operation of the first pump unit 11 will be mainly described.

  The eccentric member 23 rotates around the drive shaft 131 by driving the motor M, so that the eccentric shaft 232 has a radius corresponding to the eccentric amount from the drive shaft 131 along the circumference of the drive shaft 131. Revolve around. The connecting rod 22 connected to the eccentric shaft 232 converts the rotation of the drive shaft 131 into the reciprocating movement of the piston 21 inside the cylinder 111. That is, the piston 21 reciprocates in the Z-axis direction while swinging in the X-axis direction in FIG. As a result, the intake and exhaust of the pump chamber 26 are alternately performed, whereby a predetermined boosting action by the first pump unit 11 is obtained. On the other hand, in the second pump unit 12, a predetermined evacuation action is obtained.

  Here, when the pump device 1 is driven, the bearing 31 mounted between the eccentric shaft 232 and the connecting rod 22 is always subjected to a variable load. Improving the durability of the bearing 31 greatly affects the life of the pump device 1. The variation in load applied to the bearing 31 increases as the variation in the clearance (the bearing internal radial clearance) over the entire circumference between the inner ring and the outer ring increases. Therefore, in order to increase the durability of the bearing, it is necessary to reduce the variation in the gap.

  As a comparative example, FIG. 8 shows a configuration example of an eccentric member in a pump device having a conventional structure. The eccentric shaft 71 of the eccentric member 70 according to the comparative example has a solid columnar structure. When the inner ring of the bearing is fixed to such an eccentric shaft 71 by press-fitting, the bearing press-fit load on the outer peripheral portion of the eccentric shaft 71 is large, and it is difficult to mount the bearing with uniform stress in the circumferential direction. As a result, after the bearing is press-fitted, the variation in the radial gap inside the bearing becomes large, and it is not easy to make the stress uniform over the entire circumference. In addition, in order to reduce the variation, even if the eccentric shaft 71 is processed by turning, grinding, etc., and tolerance management is performed at, for example, 10/1000, sufficient improvement cannot be expected.

  On the other hand, in the pump device 1 of the present embodiment, the eccentric shaft 232 has a hollow structure, so that the eccentric shaft 232 can be easily deformed in the axial direction (radial direction), and the outer circumferential surface of the eccentric shaft 232 It is possible to reduce the press-fitting load of the bearing 31 and to reduce the force of expanding the inner ring 31a outward. Thereby, the variation of the internal radial clearance of the bearing 31 can be reduced, and the uniformity of stress over the entire circumference of the bearing 31 can be improved.

  FIG. 9 is a result of an experiment showing the relationship between the internal radial clearance (horizontal axis) of the bearing and the life of the bearing (vertical axis) by comparing a solid structure eccentric shaft and a hollow structure eccentric shaft. is there. The life ratio on the vertical axis is the relative value of the life when the internal radial clearance is an appropriate value (0.000), and the polarity of the numerical value on the horizontal axis is more than the appropriate value. When it is large, it is expressed as positive, and when it is smaller than the appropriate value, it is expressed as negative.

  As shown in FIG. 9, the service life decreases as the internal radial clearance deviates from the appropriate value. In particular, when the clearance between the inner ring and the outer ring is smaller than the proper value, it is larger than the proper value. The rate of life reduction is large. This indicates that the greater the pressure that the inner ring receives radially outward when the bearing is pressed into the eccentric shaft, the greater the influence on the bearing life.

  In FIG. 9, C <b> 1 shows the variation of the bearing internal radial clearance in the eccentric shaft of the solid structure according to the comparative example, and C <b> 2 shows the variation of the bearing internal radial clearance in the eccentric shaft of the hollow structure according to the present embodiment. Show. L1 represents the variation in the bearing life of the eccentric shaft having the solid structure according to the comparative example, and L2 represents the variation in the bearing life of the eccentric shaft having the hollow structure according to the present embodiment.

  As apparent from FIG. 9, according to the present embodiment, the variation in the radial clearance inside the bearing can be reduced, and the compressive stress on the radially outer side of the inner ring at the time of press-fitting can be reduced, so that an ideal radial clearance can be obtained. Can be realized. As a result, the expected bearing life can be secured stably, so that the life of the pump device can be increased.

  Further, according to the present embodiment, since the eccentric shaft 232 is formed on the eccentric member 23 which is a separate member from the drive shaft 131 and the connecting rod 22, the assembly workability of the drive shaft 131 and the connecting rod 22 is improved. In addition, the length of the drive shaft 131 can be shortened. Therefore, the load of the bearing 32 that supports the drive shaft 131 can be reduced, and the life of the pump device 1 can be further improved.

  Furthermore, since the eccentric member 23 is made of a sintered body, it is possible to stably obtain the eccentric member 23 having excellent shape accuracy and having the required mechanical strength. In addition, since a high melting point material or a plurality of types of materials that do not dissolve in each other can be used, the range of material selection can be expanded.

  The embodiment of the present invention has been described above, but the present invention is not limited to the above-described embodiment, and it is needless to say that various modifications can be made without departing from the gist of the present invention.

  For example, in the above embodiment, the pump device that drives the first pump unit 11 and the second pump unit 12 with the common drive unit 13 has been described as an example, but the pump device having a single pump unit is described. It is possible to apply to the same.

  Moreover, in the above embodiment, although the eccentric member 23 was comprised by the sintered compact, it is not restricted to this, You may comprise by casting or die-cast components. Such a configuration can also reduce the variation in the internal radial clearance of the bearing and improve the bearing life.

  Furthermore, as described above, the pump device according to the present invention is not limited to the oscillating piston type pump but can be similarly applied to other reciprocating pumps such as a diaphragm pump.

DESCRIPTION OF SYMBOLS 1 ... Pump apparatus 11 ... 1st pump part 12 ... 2nd pump part 13 ... Drive part 21 ... Piston 22 ... Connecting rod 23 ... Eccentric member 31 ... Bearing 50 ... Counterweight 100 ... Pump case 111 ... Cylinder 131 ... Drive shaft 231 ... Connecting hole 232 ... Eccentric shaft M ... Motor

Claims (5)

A piston,
A pump case having a cylinder for accommodating the piston;
A motor having a drive shaft and fixed to the pump case;
An eccentric member connected to the drive shaft and having a hollow eccentric shaft formed eccentric with respect to the rotation center of the drive shaft;
A first end connected to the piston, and a second end formed with a fitting hole to be fitted to the eccentric shaft, and the rotation of the drive shaft in the cylinder A rod member that converts the reciprocating movement of the piston;
A pump device comprising: a first bearing that is mounted between the eccentric shaft and the fitting hole and rotatably supports the eccentric shaft with respect to the rod member. The pump device according to claim 1,
The eccentric member further includes a base block having a first surface in which a connection hole connected to the drive shaft is formed and a second surface in which the eccentric shaft is formed. The pump device according to claim 2,
A pump device further comprising a second bearing fixed to the pump case and rotatably supporting the drive shaft. The pump device according to claim 2,
The eccentric member is a pump device configured by a sintered body. The pump device according to any one of claims 1 to 4,
A pump device further comprising a counterweight attached to the eccentric member and rotating together with the eccentric member.

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