JPS6215503Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a valve device for a compressor, and particularly to its discharge hole structure.

A conventional compressor valve device is shown in FIG. In the figure, 1 is a cylinder, 2 is a piston that reciprocates inside the cylinder 1, 3 is a valve plate attached to the top of the cylinder, 4 is a suction hole drilled in the valve plate 3, and 5 is a suction hole that opens and closes the suction hole 4. A valve, 6 is a discharge hole drilled in the valve plate 3, 7 is a discharge valve that opens and closes the discharge hole 6, 8 is a valve holder that restricts the movement of the discharge valve 7, 9 is a closed chamber formed in the upper part of the valve plate 3 It is a cover that does.

In the conventional valve device configured in this way, when the piston 2 is at the top dead center position, a gap 6c is formed in the cylinder by the gap 2c between the piston 2 and the valve plate 3 and the discharge hole 6. However, this gap 2c+6c has a great significance on the performance of the reciprocating compressor. In other words, if the gap 2c + 6c is too large, a lot of high-pressure gas will be left behind in the cylinder even at the end of the discharge stroke, and the pressure in the cylinder will not fall below the suction pressure even when the suction stroke begins, so the suction The timing at which gas flows into the cylinder is delayed, resulting in a decrease in the amount of suction gas sucked in during one rotation. In other words, the volumetric efficiency decreases. Conversely, if the gap 2c+6c is small, the amount of high-pressure gas left behind in the cylinder will be small, making it easier for suction gas to flow in during the suction stroke. In other words, the volumetric efficiency increases. Therefore, in order to increase the volumetric efficiency, it is necessary to make the gap 2c+6c as small as possible.

Generally, the gap 2c can be made smaller, but since the valve plate 3 has a certain thickness in the gap 6c, if this is to be made smaller, the inner diameter of the discharge hole 6 has to be made smaller. Discharge hole 6
If the inner diameter of the cylinder is made smaller, it is advantageous to increase the volumetric efficiency during high compression ratio operation with low gas flow rate.
On the other hand, during low compression ratio operation with a large flow rate, the cross-sectional area of the discharge hole 6 serving as a gas passage is small, which causes resistance, and as a result of the temperature rise, the suction gas is overheated, resulting in no improvement in volumetric efficiency. Furthermore, the resistance required for discharge increases the workload of the compressor, making it impossible to operate economically. For the reasons mentioned above, with conventional valve devices, even if volumetric efficiency decreases during high compression ratio operation,
The gap 6c had to be increased to some extent.

The present invention was devised in view of these drawbacks, and one embodiment of the present invention will be described below.

FIG. 3 shows a discharge part of a valve device of a compressor showing an embodiment of the present invention. In the figure, 10 is a slider fitted into the inner wall of the discharge hole 6, and 11 is a back of the slider 10 and tightly attached to the valve plate 3. These two members 10 and 11 constitute a throttling mechanism, which causes the block 11 to deform due to heat. The slider 10 moves forward and backward in the radial direction of the discharge hole 6. Note that in this figure, other symbols are the same as in FIG. 1. In the valve device configured in this way, during low compression ratio operation with a large gas flow rate, the temperature of the discharged gas is relatively low, so the thermal expansion of the block 11 is small, and the slider 10 cannot enter the inside of the discharge hole 6. First, the discharge hole 6 can ensure a sufficient gas passage area. Conversely, during high compression ratio operation with a small gas flow rate, the temperature of the discharged gas generally rises, so the temperature of the block 11 also rises.
Thermal expansion pushes the slider 10 toward the center of the discharge hole 6, as shown in FIG. In such a state, the discharge hole 6 is narrowed due to the intrusion of the slider 10, and as a result, the gap 6c is reduced, and the volumetric efficiency is improved. Note that the volumetric efficiency η _V in the present invention can be theoretically expressed by the following equation.

Δη _V = (v ₂ /V ₂ ) (1-E ^1/n ) (1-α) where V ₂ is the stroke volume of the piston, and v ₂ is the original top clearance (2c and 6 in Figure 1).
c), E is the compression ratio, n is the polytropic index, and α is the reduction rate of the top clearance v ₂ .

Further, in this embodiment, an example is shown in which the block 11 is used in the aperture mechanism, but the present invention is not limited to this, and the block 11 may be made of a spring-like material or a bimetal that expands and contracts with temperature changes. .

As explained above, according to the present invention, a throttling mechanism is provided which includes a block having a large expansion coefficient in a recess provided in the inner wall of the discharge hole, and a slider that advances and retreats in the radial direction of the discharge hole by thermal deformation of this block. Because of this provision, a sufficient gas passage area of the discharge hole can be ensured during low compression ratio operation, and the gas passage area of the discharge hole can be reduced during high compression ratio operation. Therefore, as shown by the broken line in FIG. 2, if there is no decrease in volumetric efficiency during low compression ratio operation, there will be no increase in compressor work, making it possible to improve volumetric efficiency during high compression ratio operation. Can be done.

[Brief description of the drawings]

Fig. 1 is a sectional view of a conventional valve device, and Fig. 2 is a sectional view of a conventional valve device.
A curve diagram showing changes in volumetric efficiency with respect to compression ratio.
The solid line shows the conventional device and the broken line shows the device according to the invention. FIGS. 3 and 4 are partial sectional views of a discharge hole portion of a valve device showing an embodiment of the present invention. In the figure, 3 is a valve plate, 6 is a discharge hole, 7 is a discharge valve, 10 is a slider, and 11 is a block with a large coefficient of thermal expansion. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Scope of utility model registration request] The compression section consists of a cylinder, a piston that reciprocates within the cylinder, and a valve plate attached to the top of the cylinder via a gasket.The valve plate has a suction hole and a discharge hole, each of which can be opened or closed. In a reciprocating compressor valve device in which a suction valve and a discharge valve are provided in contact with a valve plate, a block with a large expansion coefficient and a block with a large coefficient of expansion are formed in a recess formed in the inner wall of the discharge hole. 1. A valve device for a compressor, comprising a throttle mechanism comprising a slider that moves forward and backward in the radial direction of a discharge hole.