JPS636478Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement in a rotary pump for sewage, which is used particularly in human waste treatment equipment and is required to have a small capacity, a relatively high head, and to allow passage of large foreign substances.

Conventionally, there has been a rotary pump in which an impeller made of a flexible elastic body and having a plurality of radial blades is elastically housed in a circular pump casing with an arcuate cam protruding from a part of the inner periphery between the suction and discharge ports. It was hot. The cams in this product are symmetrical on the left and right sides (discharge side and suction side) with respect to the maximum thickness part, and in order to prevent the discharge side and suction side from communicating and causing leakage back, there is always at least one cam. The blades of the cam must be tightly engaged with the cam. To achieve this, it was necessary to make the length of the cam chord longer than the straight line distance between the blade vertices in the free state.

In pumps with a large number of blades, the string length of the cam can be set relatively short; however, for example, sewage pumps used in human waste treatment equipment, etc., have a small capacity, high head, and are required to allow large amounts of foreign matter to pass through. Since the pump is small, the number of blades must be reduced and the volume between the blades must be increased.

In this case, as shown in Figures 1 and 3, the cam chord length L' ₁ becomes considerably longer than the blade spacing L.
Therefore, the angle θ between the rush port and the discharge port becomes large. This is because the circumferential distance between the suction port and the discharge port on the opposite side of the cam becomes short, which increases leakage and return loss of discharge pressure, making it impossible to obtain an efficient high-head pump.

Moreover, since the blade cannot have much elasticity to avoid wear,
In a symmetrical cam as shown in the figure, where the distance from the impeller center to the inner surface of the cam increases rapidly after the maximum thickness, the restoring force due to the elasticity of the bent blade tip cannot follow the rotational speed. Experiments have revealed that a gap is created between the cam surface and the discharge pressure leaks to the suction side through the gap, which also causes a decrease in efficiency.

In view of the above-mentioned current situation, the purpose of this invention is to obtain a highly efficient rotary pump for filth that has a small capacity, high head, and large foreign matter passage capacity.The cam installed inside the pump casing is By setting the length of the chord shorter than the straight line distance between the impeller blade vertices in the free state, the angle between the suction and discharge ports on the cam side is made smaller, and the thickness gradually increases from the discharge side end to the approximate center of the cam. The thickness is the same from the approximate center to the front blade engagement position when the rear blade starts closing, and the inner thickness is the same from the approximate center to the front blade engagement position when the rear blade starts closing. The periphery is characterized in that the radius is approximately the same as the radius of the inner periphery of the same thickness portion, and the center is a curved line on the opposite side, connected to the curved line that gradually increases from the center of the impeller.

To explain in detail the embodiment shown in the figure, 1 is a circular pump casing with an opening of an angle θ' and a suction port 1a.
and a discharge port 1b are formed, and the suction/discharge port 1
An arcuate cam 2 is provided on the inner circumference between a and 1b.

3 is an impeller having a plurality of radial blades 3a made of a flexible elastic material such as rubber;
The pump casing 1 is fitted with a key in elastic contact with the pump casing 1, and is rotated in the direction of the arrow.

The cam 2 has a chord length L' ₂ with respect to the linear distance L between the vertices of the impeller blades 3a and 3a in the free state (Fig. 3), so that L>L' ₂ and the angle θ' between the suction and discharge ports is made as small as possible. It is formed so that the thickness gradually increases from the discharge side end to the approximate center of the cam, and the maximum thickness T is reached at the approximate center, which is approximately 1/2 of the string length L' ₂ , and the thickness of the rear blade 3a is increased. A curve concentric with the outer periphery with the same thickness up to the engagement position P of the front blade 3a at the start of confinement (see Figures 2 and 4),
In other words, it is formed with a radius of R ₁ - T = R ₂ for the radius _R 1 of the outer circumference, and the radius R ₃ is approximately the same length as the radius R ₂ from the point P onwards to the suction side end. The radius R ₂ is connected to the opposite side of the curve as a curve that gradually increases from the impeller center.

Therefore, during pump operation, even if the chord length L' ₂ of the cam 2 is somewhat shorter than the distance L in the free state of the blades 3a, the position where the blade 3a in the latter stage starts to engage with the cam 2 is determined. , the front blade 3a is still engaged with the cam 2 in its maximum bending state (the state shown in Figure 2), so the pressure on the discharge port 1b side leaks to the suction port 1a side via the cam 2 section. There's nothing to do. Moreover, since θ>θ' allows for a larger circumferential distance between the suction and discharge ports 1a and 1b on the opposite side of the cam 2 compared to the conventional one shown in FIG. The fear of this will also be reduced. Furthermore, since the front blade 3a is restored to the free state according to the curve that gradually increases after the point P, the pressure inside the confinement part does not change suddenly or the blade rebounds, etc., and therefore vibration in this part is prevented.・There is no risk of noise generation.

In this way, in the rotary pump for filth according to the present invention, even though the length of the cam chord is set shorter than the straight line distance between the impeller blade vertices in the free state, the thickness from the discharge side end to the approximate center of the cam is small. The blade is formed to gradually increase in thickness, with maximum thickness at approximately the center, which reduces vibration without giving the blade sudden bending.
In the extended life state, the bending state is maintained at the maximum until confinement by the subsequent blade begins, and thereafter it is restored along a gradually increasing curve.
without strengthening the elasticity of the impeller blades.
The close followability of the front stage blade to the cam up to the closing start position of the rear stage blade is improved to ensure that the number of blades in close contact with the cam is always one or more, thereby eliminating any leakage of discharge pressure from the cam side to the suction side. In addition to this, the angle between the discharge port and the suction port on the side opposite to the cam can be increased to reduce the loss due to the return of the discharge pressure on this side. Furthermore, after the start of confinement, the front-stage blade gradually restores itself along the gradual increase curve of the latter half of the cam, so compared to a blade that restores rapidly, vibrations caused by sudden changes in confining pressure or rebounding of the blade, etc. There is no fear of noise.

Therefore, even a pump with a small capacity, high head, and large foreign matter passage capacity, that is, a pump with a small number of blades, can achieve high efficiency.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an example of a conventional pump.
Figures 2 to 4 show one embodiment of the present invention, with Figure 2 being a cross-sectional view, Figure 3 being a front view in a free state showing part of the impeller, and Figure 4 being an enlarged front view of the cam. be. In the figure, 1 is the pump casing, 1a is the suction port,
1b is the discharge port, 2 is the cam, 3 is the impeller, 3a
indicates the blade, and T indicates the maximum thickness of the cam.

Claims (1)

[Scope of utility model registration request] An impeller having a plurality of radial blades made of a flexible elastic body is elastically installed in a circular pump casing with an arcuate cam protruding from a part of the inner periphery between the suction and discharge ports, wherein the cam The length of the chord is set to be shorter than the straight line distance between the vertices of the impeller blades in the free state, and the thickness is gradually increased from the discharge side end to approximately the center of the cam, with the maximum thickness at approximately the center, The thickness is the same from the approximate center to the front blade engagement position when the rear blade starts closing, and the inner thickness is the same from the front blade engagement position when the rear blade starts closing. A rotary pump for filth, characterized in that the periphery has a radius approximately the same as the radius of the inner periphery of the same thickness portion, and the center is a curved line on the opposite side, connected to form a curved line that gradually increases from the center of the impeller.