JPS6018634Y2 - Compressor discharge valve device - Google Patents

Description

[Detailed explanation of the invention] This invention relates to the improvement of a discharge valve device for a compressor, and more specifically, the invention is concerned with improving the discharge valve device of a compressor. The present invention relates to a discharge valve device which prevents vibration interference between arms, improves the strength and reliability of the arms, and reduces noise.

1 and 2 show a conventional example of a valve holding plate with two arms for a refrigeration compressor.

The structure around the valve holding plate of a conventional discharge valve device will be explained with reference to these figures.

In a refrigeration compressor that uses a large amount of refrigerant, a plurality of discharge ports 2a, 2b and one suction port 3 are usually provided in the valve plate 1 due to space restrictions in the cylinder head.

A discharge valve 4, which is stamped and formed from a single plate, is arranged opposite to the discharge ports 2a*2b.

When the refrigeration compressor operates, the discharge valve 4 moves violently,
Stress acts repeatedly on the discharge valve 4.

For this reason, in order to suppress the lift height of the discharge valve below a certain value and to reduce the stress generated in the discharge valve below the fatigue strength of the material composing the discharge valve, the valve holding plate 5 is aligned with the discharge valve 4 using bolts 6. has been done.

Note that a washer 7 is inserted between the head of the bolt 6 and the valve holding plate 5.

In addition, in a refrigeration compressor provided with a plurality of discharge ports 2a and 2b, the valve holding plate 5 is formed by punching out a single plate like the discharge valve 4 and forming a plurality of arms having the same length and shape. 5a, 5b
It is formed into a cantilever shape with .

The valve holding plate 5 is fixed to the valve plate 1 at one end in order to facilitate machining and assembly, and the tips of arms 5a and 5b formed at the other end are positioned above the discharge ports 2a and 2b. be incorporated into.

Next, the vibration behavior of the valve holding plate during operation of the refrigeration compressor will be explained.

One end of the valve holding plate 5 is fixed, and the other end is free.

The valve holding plate 5 placed in such a state is
When the discharge valve 4 collides with the valve holding plate 5 due to the movement of the discharge valve 4, it vibrates elastically.

This elastic vibration occurs in each arm 5a. If the lengths of the arms 5b are slightly different, a so-called interference effect occurs where the arms are influenced by the vibrations of adjacent arms.

Now, this transmitted fluctuating external force is P.

Let sin ωt.

In addition, if the deflection of the valve holding plate 5 in the out-of-plane direction is y (xtt), the distance from the fixed end is X, and the cross-sectional shape of the arm is uniform to simplify the explanation, then the valve holding plate 5 is Deflection y (xt
t) is Y(x, t)=, Σ(Ii (t) xXi (x)
--------(1) 1=1 (where qi(t) is a relational factor and Xl(X) is a displacement mode).

From the balance of the work done by the inertial force of the valve holding plate, the work done by the elastic force of the valve holding plate, and the work done by the external force, a differential equation regarding the above relational factor qi(t) is derived, and qj( t) + ωj2(Ii (t) = 2F (t)
......(2) However, t22Xj (young EIg f.

(2X2)2dx””= rAf (Xj(→)・4
- ÷Af(Xj (effect) 2dX F (t) = Pocosωt (E is the longitudinal elastic modulus, ■ is the second moment of area,
A is the cross-sectional area, 1 is the length of the arm, γ is the specific weight, and g is the acceleration of gravity).

1 = 0 and qj (o) = Qj (o) = O, so the solution to equation (2) is Pok2 - q" t) = mJ2- m・-0°osw t -c
osmft'), , , (6°).

Now, consider the case where the natural angular frequencies of adjacent valve holding plates are very close, and if the difference between the two is 2E, the fluctuation angular frequency ω of the external force is expressed as ω = ωj + 2E, so this can be expressed as equation (6). If you substitute and rearrange it, it will be ok2 qj (t) = −sin (ωj+E) t
*5int t 2 t (ωJ+E)
......(7) The following relationship is obtained.

From the above equation (7), qj(t) rapidly oscillates at an angular frequency of ωj 10t, but this amplitude is 2? It can be seen that it fluctuates periodically with a period of r/l.

This state is shown in FIG.

This result shows that when the natural frequencies of the arms of adjacent valve holding plates are very close, the vibration of one valve holding plate arm is transmitted to the arm of the other valve holding plate, causing a beating phenomenon. means.

Even if the dimensions of the arms of the valve holding plate are designed to be exactly the same, they cannot be finished to exactly the same dimensions due to machining accuracy.

For this reason, with the conventional shape of the valve holding plate, the vibrations of adjacent valve holding plates interfere with each other and cause a humming phenomenon.
The vibration of the valve holder plate is not easily attenuated, and the number of repetitions of stress on the valve holder plate increases per discharge valve, and the valve holder plate must be tightened with sufficient consideration to prevent bolts from loosening. .

Furthermore, the whirring phenomenon of the valve holding plate is also a cause of increased noise.

This idea uses valve holding plates with slightly different dimensions and shapes, such as the length of the arms of the valve holding plates.
The object of the present invention is to provide a discharge valve device that eliminates the above-mentioned conventional drawbacks.

An embodiment of this invention will be described below with reference to FIG. 4.

In FIG. 4, the lengths of the arms 5a and 5b of the valve holding plate 5 are made different from each other, and the other configurations are the same as those in FIGS. 1 and 2.

In the case of a uniform cross-sectional shape, as is clear from equation (3) above, the natural frequency of each arm of the valve holding plate depends on its second moment of area, cross-sectional area, and length.

On the other hand, the moment of inertia and cross-sectional area are proportional to the width.

Therefore, from equation (3), it can be seen that in order to change the natural frequency of each piece 5a, 5b of the valve holding plate 5, it is effective to change the plate thickness or length of the arm.

However, since the valve holding plate is generally formed by punching out a steel plate having a constant thickness, it is economically and technically disadvantageous to change the thickness of the arm.

Therefore, it can be seen that the most effective way to change the natural frequency of each arm is to gradually change the length of each arm.

Therefore, in this embodiment, the lengths of the arms of the valve holding plate are slightly different, so that their natural frequencies are shifted from each other.

And the beat fluctuation cycle 2? r/ξ is very small, and a slight difference in arm length due to machining accuracy causes a beat phenomenon, so if the natural frequency is actively shifted as in this example, the beat phenomenon can be easily eliminated. do.

Fig. 5 shows a comparison of the vibrations generated in the valve holding plate between the conventional product and the above-mentioned embodiment, where a shows the conventional product and b shows the embodiment, and the vertical axis is the The horizontal axis represents time.

As is clear from FIG. 5, in the embodiment of this invention, the damping occurs immediately after the discharge valve collides, and the beating phenomenon seen in the conventional product does not occur.

In addition, in the above-mentioned embodiment, the length of the valve holding plate is changed, but this invention can obtain substantially the same effect even if the valve holding plate has arms having different cross sections. be.

As explained above, this idea is based on the length of the arm of the valve holding plate,
By changing the dimensions and shapes such as width, the natural frequencies of these individual arms are changed, and the beating phenomenon that occurs due to very slight differences in the natural frequencies of the individual arms is eliminated. It is.

As a result, the stress and tightening of the valve holding plate can alleviate the loosening of bolts and noise, and as a result, the reliability of the compressor can be improved.

[Brief explanation of drawings]

Fig. 1 is a plan view showing the area around the valve holding plate of a conventional refrigeration compressor, Fig. 2 is a sectional view of the same side, Fig. 3 is an explanatory diagram of the beat phenomenon, and Fig. 4 is an example of an embodiment of this invention. FIG. 5 is a plan view showing the area around the valve holding plate, and is an explanatory view comparing the vibration generation state between the conventional product and this invented product. 1...Valve plate, 2a, 2b...Discharge port,
3... Suction port, 4... Discharge valve, 5...
...Valve holding plate, 5a, 5b...Arm, 6...
...Bolt, 7...Washer. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Scope of utility model registration request] It is equipped with a plurality of automatic valves that open and close a plurality of discharge ports provided on a valve plate, and a valve holding plate having a plurality of arms that supports the back surface of these automatic valves in order to suppress the lift height of the automatic valves. In the discharge valve device for a compressor, the arms of the valve holding plate are made to have different dimensions such as length and width, and shapes so that the arms have different bending natural frequencies. Machine discharge valve device.