JPH0295781A - Reciprocating and rocking type piston pump - Google Patents

Abstract

PURPOSE:To abate the extent of pump noise by forming a grade, pointing to place nearer to a cylinder inner surface at the side where a capacity extending rate in a pump case is enhanced by rocking motion of a piston at an inlet stroke starting stage, in hole surface of a suction port. CONSTITUTION:In this piston pump 10, an nd 16 of a piston 15 is connected to an eccentric pin 14 of a drive shaft 13 being supported on a pump boxy 11 via a bearing 12. A pump case 10A is formed by the piston 15, a cylinder 20 and a cylinder head 21. In this cylinder head 21, there are provided with an exhaust port and an inlet valve 24 opening to the inside and outside of the pump case 10A and an exhaust reed valve and an inlet reed valve 26. In this case, a taper hole surface 31 with a specified angle theta is installed in the inlet port 24. Then, this taper hole surface 31 is directed to place nearer to a cylinder inner surface at the side where a capacity extending rate in the pump case 10A is enhanced by rocking motion of the piston 15 at an inlet stroke starting stage.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a reciprocating oscillating piston pump.

[Prior art] Conventionally, vacuum pumps, air compressors, etc.
There is a piston pump as described in Japanese Patent No. 45912. This piston pump has an end of the piston connected to an eccentric pin of a drive shaft supported by the pump body, and is disposed in a cylinder provided in the pump body so as to reciprocate in a rocking state, A cylinder head is provided on the piston top dead center side of the cylinder, a pump chamber is formed by the cylinder, the piston, and the cylinder head, and an intake hole and an exhaust hole that open into and outside of the pump chamber are provided as an intake valve and an exhaust valve, respectively. The above cylinder head is provided with the following.

FIG. 7 is a sectional view showing the main parts of this biston pump, in which 1 is a piston, 2 is a cylinder, 3 is a cylinder head, 4 is a pump chamber, 5 is an intake hole, and 6 is an exhaust hole.

In this piston pump, (a) during the intake stroke, as shown in FIG. 7, the piston 1 descends from the top dead center;
Air is taken in from the intake hole 5 due to the negative pressure caused by the volume expansion of the pump chamber 4 accompanying this.

Further, during the (b) exhaust stroke, the piston 1 rises from the bottom dead center, and the positive pressure caused by the volume reduction of the pump chamber 4 is used to exhaust the air from the exhaust hole 6.

[Problems to be Solved by the Invention] However, the piston pump described above generates a large amount of pump noise during operation. Possible causes of the noise include, in addition to motor noise, intake fluid noise, exhaust fluid noise, piston sliding noise, intake and exhaust valve operation noise, and bearing rolling noise.

The present invention aims to reduce pump noise of a piston pump.

[Means for Solving the Problem] The present invention connects an end of a piston to an eccentric pin of a drive shaft supported by a pump body, and reciprocates the piston in a swinging state within a cylinder provided in the pump body. a cylinder head is provided on the piston top dead center side of the cylinder, a bomb chamber is formed by the cylinder, the piston, and the cylinder head, and an intake hole opens inside and outside of the pump chamber; In the reciprocating piston pump, in which the cylinder head is provided with an intake valve and an exhaust hole, respectively, the intake hole is 0,
The pump is configured to include a sloped hole surface oriented toward the inner surface of the cylinder on the side where the volume expansion rate of the pump chamber increases due to the rocking of the piston at the start stage of the intake stroke.

[Function] According to the inventor's considerations, at the start of the intake stroke when the negative pressure in the pump chamber is high and the intake flow rate to the pump chamber is high, the volume expansion rate of the pump chamber is reduced by one cylinder due to the rocking of the piston. It is higher on the inner surface side and lower on the inner surface side of the other cylinder. The present inventor has discovered that in this intake stroke, smoothing the intake (filling of gas) into the region with a high volume expansion rate is as follows:
It was thought that this would reduce the generation of intake fluid noise.

However, in conventional piston pumps, the intake hole is configured with a straight hole surface parallel to the axial direction of the pump chamber, ensuring directivity of intake air to the area with a high volume expansion rate in the pump chamber. It is not configured.

Therefore, in the present invention, as described in claim 1, the hole surface of the intake hole is provided near the inner surface of the cylinder on the side where the volume expansion rate of the pump chamber increases due to the rocking of the piston at the start stage of the intake stroke. By adding a directional slope surface, the pump noise was reduced as a result.

This is because, according to the present invention, the negative pressure in the pump chamber is high and the intake flow rate to the pump chamber is high, so at the start of the intake stroke, where intake fluid noise is likely to occur, an area where the volume expansion rate in the intake pump chamber is high. It is thought that this enabled the fluid to flow smoothly into the intake fluid, reducing the generation of intake fluid noise and, as a result, reducing pump noise.

[Example] Fig. 1 is a sectional view showing one embodiment of the present invention, and Fig. 2 is a sectional view showing an embodiment of the present invention.
A cross-sectional view taken along the line ■-■ in the figure, Figure 3 is a stroke diagram showing the operating state of the piston pump, Figure 4 is a schematic diagram showing the shape of the intake hole, and Figure 5 shows other shapes of the intake hole. The schematic diagram, FIG. 6, is a schematic diagram showing another shape of the intake hole.

As shown in FIGS. 1 and 2, the piston pump 10 includes a drive shaft 13 supported by a pump body 11 via a bearing 12.
An end 16 of a piston 15 is connected to an eccentric pin 14 of the piston 15 . The eccentric pin 14 is fixed to the drive shaft 13 by a set screw 17, and the end 16 of the screw 15 is connected to the eccentric pin 14 via a bearing 18. 19 is an air cooling fan fixed to the drive shaft 13. A drive motor is connected to an end (not shown) of the drive shaft 13 .

The piston pump 10 includes a cylinder 20 in a pump body 11.
A cylinder head 21 is provided on the piston top dead center side of the cylinder 20, and a head cover 22 is provided above the cylinder head 21.

The piston 15, cylinder 20, and cylinder head 21 form a pump chamber 10A. The cylinder head 21 includes an exhaust hole 23 and an intake hole 24 that open to the inside and outside of the pump chamber 10A, as well as an exhaust reed valve 25 and an intake reed valve 26. The head cover 22 also has an exhaust connection port 27.
and an intake connection port 28. 29 is cylinder 20
This is an O-ring interposed between the cylinder head 21 and the cylinder head 21. Reference numeral 30 denotes a partition wall that separates the exhaust connection port 27 and the intake connection port 28 of the head cover 22.

That is, when the drive shaft 13 is driven by a motor or the like, the piston 15 of the piston pump 10 moves as shown in FIG. 3(A).
As shown in ~(D), the piston 15 is reciprocated in a rocking state, and the exhaust stroke in FIG. 3(B) and the intake stroke in FIG. 3(D) are repeated.

Therefore, the piston pump 10 is
As shown in the figure, the intake hole 24 is provided with a sloped hole surface 31 (gradient angle O). The sloped hole surface 31 is formed in the pump chamber 10A by the rocking of the piston 15 at the start stage of the intake stroke.
The direction is toward the inner surface of the cylinder where the volume expansion rate is higher.

Next, the operation of the above embodiment will be explained.

In the piston pump 10, the degree of negative pressure in the pump chamber 10A is high, and the pump chamber 1. At the start of the intake stroke when the intake air flow rate to the OA is high, the volume expansion rate of the pump chamber 10A is high on the inner surface of one cylinder due to the rocking of the piston 15, and is low on the inner surface of the other cylinder. As described above, the inventor of the present invention believed that the generation of intake fluid noise can be reduced by smoothing the intake (filling of gas) into the region with a high volume expansion rate during the intake stroke.

However, in the above embodiment, the intake hole 24 has a sloped hole surface oriented toward the inner surface of the cylinder on the side where the volume expansion rate of the pump chamber 10A increases due to the rocking of the piston 15 at the start stage of the intake stroke. 31 was applied, and as a result, the pump noise was reduced.

According to the experimental results of the present inventor, by providing the above-mentioned inclined hole surface 31 (gradient angle O=1'2.5 degrees), the conventional noise of the piston pump 10 of 66 dIl (A) 30 cm is reduced to 63 dB (Δ) Therefore, a noise reduction effect of 3 dB (A) was observed.

According to the above embodiment, the negative pressure in the pump chamber 10A is high and the intake flow rate to the pump chamber 10A is high. It is thought that this allows smooth flow into areas with a high expansion rate, reduces the generation of intake fluid noise, and as a result reduces pump noise.

Further, the sloped hole surface 31 of the intake hole 24 forms, together with the opposing straight hole surface, an intake hole cross section that gradually decreases in the intake air inflow direction ζ.

Therefore, the intake air flow is constricted as it flows into the intake hole 24, and is guided along the sloped hole surface 31, thereby further ensuring directivity to each region having a high volume expansion rate.

In the practice of the present invention, the sloped hole surface provided to the intake hole 24 is as shown in the sloped hole surface 41 shown in FIG.
It may be provided on the hole surface side opposite to the gradient hole surface 31 of the above embodiment. Further, the inclined hole surface 51 shown in FIG.
52, the holes may be provided on two opposing hole surfaces.

[Effects of the Invention] As described above, according to the present invention, pump noise of a piston pump can be reduced.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing one embodiment of the present invention, and FIG.
A cross-sectional view taken along the line ■-■ in the figure, Figure 3 is a stroke diagram showing the operating state of the piston pump, Figure 4 is a schematic diagram showing the shape of the intake hole, and Figure 5 shows other shapes of the intake hole. FIG. 6 is a schematic diagram showing another shape of the intake hole, and FIG. 7 is a schematic diagram showing a conventional example. DESCRIPTION OF SYMBOLS 10... Piston pump, 10A... Pump chamber, 13... Drive shaft, 14... Eccentric pin, 15... Piston, 16... End part, 20... Cylinder, 21... - Cylinder head, 23...Exhaust hole, 24...Intake hole, 25...Exhaust saw 1-valve, 26...Intake reed valve, 52...Gradient hole surface.

Claims (1)

[Claims] (1) An end of a piston is connected to an eccentric pin of a drive shaft supported by a pump body, and the piston is disposed in a cylinder provided in the pump body so as to reciprocate in a rocking state, A cylinder head is provided on the top dead center side of the piston, a pump chamber is formed by the cylinder, the piston, and the cylinder head, and an intake hole and an exhaust hole that open to the inside and outside of the pump chamber are provided with an intake valve and an exhaust valve, respectively. In the reciprocating oscillating piston pump, which is provided in the cylinder head in such a state that the intake hole is oriented toward the inner surface of the cylinder on the side where the volume expansion rate of the pump chamber is high due to the oscillation of the piston at the start stage of the intake stroke. A reciprocating oscillating piston pump characterized by having a sloped hole surface.