JPH0736134Y2 - Plunger pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION << Industrial Application Field >> The present invention relates to a plunger pump used as a hydraulic power source such as a power steering device and a suspension device of an automobile.

<< Prior Art >> A radial plunger pump, which is generally used as a hydraulic power source for a hydraulic system for automobiles as described above, is provided with a plurality of casings by rotating an eccentric cam fitted to a drive shaft and housed in the casing. The plunger provided is operated to suck, compress and discharge the hydraulic oil. FIG. 3 is a vertical cross-sectional view of an example of such a conventional plunger pump.

In this plunger pump 1, an eccentric cam 4 that is fitted into a shaft 3 and rotates is housed inside a casing 2, and plungers 5 are provided at a plurality of circumferential positions facing the eccentric cam 4. . Inside each plunger 5, a piston 6 that contacts the outer peripheral surface of the eccentric cam 4 is arranged. The piston 6 is always in contact with the outer peripheral surface of the eccentric cam 4 by the urging force of the coil spring 7, and reciprocally slides in the plunger 5 in the radial direction as the eccentric cam 4 rotates. By the reciprocating operation of the piston 6 of the plunger 5,
The hydraulic oil sucked from the suction pipe 8 into the suction chamber 9 is compressed, and the high-pressure hydraulic oil is sent from the discharge chamber 10 through the discharge port 11 to the hydraulic device.

The shaft 3 having the eccentric cam 4 fitted therein is rotatably supported at one end thereof by a bearing metal 12 and at an intermediate part thereof by a bearing 13, and the other end thereof penetrates the casing 2 to project outside the machine. A rotary drive means such as a V pulley (not shown) is provided in the portion. Front of bearing 13 (right side in the figure)
A seal ring 14 and a packing body 15 are fitted in a portion of the shaft 3 through which the casing 2 penetrates, and the liquid tightness of the suction chamber 9 is maintained by these seal mechanisms.

<< Problems to be Solved by the Invention >> In the plunger pump 1 as described above, since suction and compression of the hydraulic oil by the operation of the piston 6 of the plunger 5 are intermittent operations, pulse pressure is generated in the intake chamber 9, Pulsation occurs in the pump body. However, in the conventional plunger pump as described above, since there is no means for absorbing pulsation in the pump body, a pulsation absorbing means is separately provided to prevent the pulsation from being transmitted to the outside. That is, generally, a pulsation preventing means (not shown) is provided in the suction side passage (source side of the suction pipe 8 shown in the drawing) to absorb the pulsation. However, as described above, since the pulsation absorbing means is separately provided, the size of the entire apparatus is increased and the cost is increased.
Since the pump body vibrates due to pulsation, it causes frequent failures and shortens the service life.

In view of such problems of the conventional plunger pump, an object of the present invention is to provide a structure of a plunger pump capable of sucking the pulse pressure generated in the suction chamber inside the pump body.

<Means for Solving the Problems> In order to achieve the above-mentioned object, the plunger pump of the present invention is provided with a seal mechanism for maintaining liquid tightness of the suction chamber in the casing in the casing penetrating portion of the shaft. A pair of snap rings are provided on both sides of the shaft in the axial direction of the mechanism, with a gap so that the sealing mechanism can make a minute movement in the axial direction of the shaft in accordance with the pulse pressure of the suction chamber. .

<Operation> In the plunger pump of the present invention configured as described above, when a pulse pressure is generated in the suction chamber, the seal mechanism of the shaft casing penetrating portion moves slightly back and forth due to the differential pressure between the suction chamber side and the outside atmosphere side. Repeat to reduce the pulse pressure.

<< Embodiment >> Hereinafter, the construction of the present invention will be described in more detail with reference to an embodiment shown in the drawings. In the drawings shown below, the same or corresponding parts as those in FIG. 3 described for the conventional example are designated by the same reference numerals, and the duplicated description will be omitted.

FIG. 1 is a vertical sectional view showing a first embodiment of a plunger pump according to the present invention. In this plunger pump 1, a seal mechanism 16 is provided outside the bearing 13 that rotatably supports the shaft 3 in the casing 2 (on the right side in the drawing), at the portion of the shaft 3 penetrating the casing 2 so that the suction chamber 9 is liquid-tight. Holding Seal mechanism 16 and bearing
A snap ring 17 is interposed between the 13 and the seal mechanism.
A snap ring 18 is interposed on the outer side of 16 and the seal mechanism 16 is arranged so as to be sandwiched between these snap rings 17 and 18.

The seal mechanism 16 includes a seal 19, a seal collar 20, and an O-ring 21. The seal 19 has its inner surface slidably contacting the peripheral surface of the shaft 3, and is press fitted into the seal collar 20. The seal collar 20 is fitted on the inner surface of the casing 2 with a clearance fit, and an O-ring 21 is fitted in a circumferential groove 20a on the outer circumference of the seal collar 20 in order to ensure liquid tightness of the clearance. There is. The width of the seal collar 20 is set to be narrower than the axial distance between the snap rings 17 and 18. Therefore, the seal mechanism 16 includes the snap rings 17, 18
Between them, the shaft 3 has a structure capable of minute movement in the axial direction.

In this way, the seal mechanism 16 can move in the axial direction by the gap d between the snap rings 17 and 18 while maintaining the liquid tightness of the suction chamber 9, so that the pump operates and the pulse pressure is generated in the suction chamber 9. Then, the seal mechanism 16 repeats the reciprocating movement in the axial direction of the shaft 3 due to the pressure difference between the suction chamber 9 side and the atmosphere side outside the pump body to attenuate the pulse pressure.

FIG. 2 is a vertical sectional view showing a second embodiment of the present invention. The seal mechanism 22 of this example is the seal 19 of the previous example of FIG.
The seal collar 20 and the O-ring 21 are integrated to form a seal 23, and a reinforcing ring 24 is fitted into the suction chamber 9 side of the seal 23. The outer periphery of the reinforcing ring 24 is in contact with the inner surface of the casing 2 with a clearance fit, and the width of the seal mechanism 22 is set to be narrower than the axial distance between the snap rings 17 and 18 as in the case of the previous example. The mechanism 22 slightly reciprocates in the axial direction of the shaft 3 by the pulse pressure in the suction chamber 9 to damp the pulse pressure.

<Effects of the Invention> As is clear from the above description, the plunger pump of the present invention is provided with a seal mechanism for maintaining the liquid tightness of the suction chamber in the casing, at the casing penetrating portion of the shaft, and the shaft of the seal mechanism. Since a pair of snap rings are provided on both sides in the axial direction of the seal mechanism so that the sealing mechanism can make a minute movement in the axial direction of the shaft in accordance with the pulse pressure of the suction chamber, it is generated in the suction chamber. The pulse pressure is damped by the axial movement of the seal mechanism, and the pulsation is prevented from being transmitted to the outside of the pump body. Therefore, it is not necessary to separately provide the pulsation absorbing means, and it is possible to prevent the apparatus from increasing in size and cost. Further, since the pulse pressure is absorbed in the pump body, the vibration of the body can be reduced, and the breakdown can be reduced and the life can be extended.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical sectional view showing a first embodiment of a plunger pump according to the present invention, FIG. 2 is a partially omitted vertical sectional view showing a second embodiment, and FIG. FIG. 6 is a vertical sectional view showing an example of a conventional plunger pump. 2 ... Casing, 3 ... Shaft, 9 ... Suction chamber, 1
6,22 …… Seal mechanism, d …… Gap.

Claims (1)

[Scope of utility model registration request] 1. A seal mechanism for maintaining liquid tightness of a suction chamber in a casing is provided at a shaft penetrating portion of a shaft, and the seal mechanism has a pulse pressure of the suction chamber on both axial sides of the shaft. Corresponding to the above, a plunger pump is provided with a pair of snap rings provided with a gap so that the shaft can be slightly moved in the axial direction of the shaft.