RU2825501C1 - Method of independent cooling of piston compressor and device for its implementation - Google Patents

Abstract

FIELD: power engineering.

SUBSTANCE: group of inventions relates to a method for independent cooling of a piston compressor and a device for its implementation and can be used in creation of high-efficiency piston machines of low and medium capacity with self-contained liquid cooling system. Method consists in the fact that the cooling liquid in jacket 2 of cylinder 1 containing piston 4 and working cavity 3 is pumped due to the pressure difference between suction cavity 9 and the environment. Suction cavity 9 on the part of the suction stroke through intermediate cavity 21 is connected to the lower part of working cavity 3 of cylinder 1 at the position of piston 4 in the lower dead point.

EFFECT: group of inventions is aimed at reduction of weight and size parameters, increase of efficiency and expansion of the compressor operating frequency range.

6 cl, 14 dwg

Description

The invention relates to the field of piston-type volumetric machines and can be used in the creation of highly efficient piston machines of low and medium productivity with an autonomous liquid cooling system.

A method of cooling piston compressors is known in which the cylinder is flowed around by a cooling liquid (see, for example, the book by B.S. Fotin, I.B. Pirumov, I.K. Prilutsky, P.I. Plastinin. Piston compressors, pp. 184-185, Fig. 6.32).

The disadvantage of this method is the need for a network source of cooling liquid, which limits the scope of their application.

A method for autonomous cooling of a piston compressor is also known, in which the cooling liquid located in the jacket of a cylinder containing a piston and a working cavity is pumped due to the pressure difference between the suction cavity and the surrounding environment (see, for example, Russian Federation Patent No. 2578776 “Method of Operation of a Volumetric Machine and Device for its Implementation”, published in BI No. 9, 03/27/2016, Figs. 4-7).

The disadvantage of the known method described in this patent is the bulkiness and large mass-dimensional parameters of the design, and the complexity of setting the operating parameters to ensure the circulation of liquid in the cooling system, which limits the range of rotation speed, efficiency and productivity of the machine.

The technical objective of the invention is to reduce the weight and size parameters, increase efficiency and expand the operating frequency range of the compressor.

The said problem is solved in that in the method of autonomous cooling of a piston compressor, in which the cooling liquid located in the jacket of a cylinder containing a piston and a working cavity is pumped due to the pressure difference between the suction cavity and the surrounding environment, according to the invention, the suction cavity on part of the suction stroke is connected through an intermediate cavity to the lower part of the working cavity of the cylinder when the piston is in the position of the bottom dead center.

In a piston compressor used to implement this method, containing a cylinder with a cooling jacket, a working cavity and a piston with a drive, a drive shaft and a mechanism for converting the rotational motion of the shaft into a reciprocating motion of the piston, suction and discharge valves installed in the suction and discharge cavity and connecting the working cavity of the cylinder with the suction and discharge lines, wherein the cooling jacket is connected to a source of cooling liquid using the suction and discharge valves, according to the invention, the suction cavity on part of the suction stroke is connected by a channel through an intermediate cavity with the lower part of the working cavity of the cylinder when the piston is in the position of the bottom dead center. Moreover, the piston may contain a cavity equipped with a check valve connecting this cavity with the working cavity of the cylinder, and an opening towards the side surface of the cylinder, coinciding with the channel when the piston is in the bottom dead center position, the suction line may be equipped with a flap connected to the drive shaft through a mechanism for moving it, made of a cam or electromagnetic type. In the latter case, the electromagnetic type mechanism may contain an inductor consisting of a fixed inductance coil, and an anchor in the form of a permanent magnet, fixed on the drive shaft with the ability to pass by the inductance coil with a small gap, and the inductance coil is connected to the coil of the electromagnet, the anchor of which is the flap, and, in addition, the cam type mechanism may contain a cam, kinematically or directly connected to the drive shaft with the ability to act on the flap.

The essence of the invention is explained by drawings.

Fig. 1 shows a diagram of a compressor in its simplest version,

Fig. 2 shows an enlarged view of its cylinder-piston group.

Fig. 3 shows a diagram of the compressor during the pumping process,

Fig. 4 shows a diagram of a compressor during the suction process,

Fig. 5 shows the stage of compressor operation during which the suction cavity communicates with the working cavity through an additional channel.

Fig. 6 shows a diagram of a compressor during the compression process.

Fig. 7 shows a diagram of a compressor with an intermediate cavity, and

Fig. 8 shows an indicator diagram of the compressor working cavity.

Fig. 9 shows the suction process in a compressor with an intermediate cavity, in which the valve into the intermediate cavity is open.

Fig. 10 shows the moment of compressor operation during the suction process with the intermediate cavity valve closed.

Fig. 11 shows the moment of compressor operation at which the intermediate cavity communicates with the suction cavity.

Fig. 12 shows the moment of operation of a compressor with an intermediate cavity during the compression process.

Fig. 13 shows a diagram of a compressor with a damper on the suction line, driven by an electromagnet, and

in Fig. 14 - driven by a cam mechanism.

The compressor (Fig. 1) comprises a cylinder 1 with a cooling jacket 2, a working cavity 3 and a piston 4 with a drive consisting of a drive shaft 5 and a crank mechanism 6 for converting the rotational motion of the shaft 5 into a reciprocating motion of the piston 4, suction 7 and discharge 8 valves installed in the suction cavity 9 and discharge 10, and connecting the working cavity 3 of the cylinder 1 with the suction 11 and discharge 12 lines, wherein the cooling jacket 2 is connected to a source of cooling liquid 13 by means of a suction 14 and discharge 15 valve.

The suction cavity 9 is connected by a channel 16 with the lower part of the working cavity 3 when the piston 4 is in the position of the lower dead center BDC, where the piston 4 comes from the upper dead center TDC. The jacket 2 is connected to the liquid source 13 through channels 17 and 18, and a heat exchanger 19 is installed on the latter. The suction line 11 is also equipped with a check valve 20 with an outlet into the intermediate cavity 21.

In Fig. 2 the length of the piston L _P , which is greater than the stroke of the piston S _{h ,} is also indicated .

Fig. 7 shows a cylinder-piston group of a compressor, in which piston 4 contains a cavity 22, equipped with a check valve 23, connecting this cavity with the working cavity 3 of cylinder 1, and an opening 24 towards the side surface of the cylinder, coinciding with channel 16 when the piston is in the position of the bottom dead center.

In this construction, the condition L _P > S _h is also satisfied .

In Fig. 8 the following notations are used:

- p - pressure in the working cavity 3;

- р _Н - discharge pressure;

- p _B - suction pressure;

- ϕ - angle of rotation of the drive shaft, starting from TDC;

- α - the angle of pressure drop at the end of the suction process;

- β - the angle of pressure drop at the beginning of the suction process;

- Δ p - pressure drop;

- a ÷ z - characteristic points of the diagram.

Fig. 13 and 14 show a diagram of a piston compressor in which the suction line 11 is equipped with a valve 25 connected to the drive shaft 5 through a mechanism for moving it.

In Fig. 13 this is an electromagnetic type movement mechanism which contains an inductor consisting of an inductance coil 27 fixedly secured to the crankcase 26 of the compressor, and an anchor in the form of a permanent magnet 28 secured through a flange 29 with a lock 30 on the drive shaft 5 with the ability to pass by the inductance coil 27 with a small gap. The inductance coil 27 is electrically connected (the connection is shown by dashed lines) to the coil 31 of the electromagnet 32, the anchor of which is the flap 25, spring-loaded in the opposite direction from the suction line 25 by a spring 33.

Fig. 14 shows a compressor with a cam-type damper movement mechanism, containing a cam 34, which is mounted on a drive shaft 5 and acts on a damper 35, mounted in a suction line 11 through a rod 36. The damper 35 is spring-loaded by a spring 37 in the opposite direction from the suction line 25. The cam 34 is fixed on the shaft 5 by a lock 38.

The processes in the working chamber 3 of the compressor occur as follows (Fig. 1 and 8).

When the drive shaft 5 rotates, the piston 4 moves downwards from the TDC position towards the BDC. At the beginning of this movement, the previously compressed gas from the dead volume enclosed between the piston bottom 4 in the TDC position and the upper section of the cylinder 1 (line a→b in Fig. 8) expands in the cavity 3. Both valves 7 and 8 are in the closed position.

The expansion continues until the pressure in cavity 3 decreases to the suction pressure p _B (point b ), when the suction valve 7 begins to open (line b→c ).

At point B, valve 7 opens completely and gas suction begins from suction line 11, accompanied by pressure fluctuations (line B→E ).

After piston 4 reaches the BDC position (point e ), the piston changes direction of movement and moves to TDC, the compression process begins, during which the pressure in cavity 3 increases (line e→ж ), which leads to the closing of valve 7.

At point zh, the gas pressure becomes equal to the discharge pressure p _H , and the discharge valve 8 begins to open (line zh → z ). At point z , the valve opens completely, and the process of gas injection into discharge line 12 begins, accompanied by fluctuations in gas pressure (line z → a ).

At point a the injection process ends, valve 8 closes, piston 4, having reached the TDC position, changes the direction of movement to the opposite, and the process is repeated.

The method of autonomous cooling of a compressor by organizing the movement of liquid through the cooling jacket due to the temporary connection of the suction cavity with the working cavity of the cylinder is carried out as follows (Fig. 2 - 6 and 8).

During the upward stroke of piston 4 from BDC to TDC (Fig. 3), valve 7 is closed, valve 8 opens when the pressure in cavity 3 reaches the discharge pressure. At this time, the pressure in suction line 11 is close to the suction pressure, and gas flows through valve 20 into cavities 21 and 9 until the moment when the pressure in these cavities becomes equal to the suction pressure, for example, equal to the ambient pressure.

Liquid from jacket 2, under the action of gravitational forces, flows into cavity 13 through channel 18 and valve 15, giving off heat to the environment through heat exchanger 19. Piston 4 closes channel 16, and there is no movement of liquid through this channel.

When piston 4 moves downwards (Fig. 4), the pressure in cavity 3 decreases and valve 8 closes. After expansion from the dead volume and pressure decreases below the suction pressure, the process of filling cavity 3 begins through the opened valve 7. In this case, the pressure in cavity 21 decreases below the suction pressure due to the resistance of valve 21, in connection with which valve 14 opens and cavity 21 begins to be filled with cooling liquid.

After piston 4 passes the middle of its stroke, its speed begins to fall, and accordingly the speed of gas movement in line 11 and the hydraulic resistance of valve 20 decrease, the pressure in cavity 21 begins to approach the suction pressure, and the speed of liquid flow from source 13 slows down.

However, when the piston approaches BDC (Fig. 5), the outlet opening of channel 16 into the cylinder opens (point d in Fig. 8), through which suction cavity 9 connects with cavity 3 of the cylinder, a sharp pressure drop in cavity 21 occurs, since the pressure in cavity 3 at this moment is significantly lower than the pressure in line 11 by the value Δ p1 , and the liquid again begins to actively flow from source 13 into cavity 21. The process of activating the movement of liquid occupies the segment d→e and angle α of the indicator diagram (Fig. 8).

After piston 4 passes the BDC position, it moves upward, cuts off channel 16 and suction cavity 9 from cavity 3, the pressure decrease in cavity 21 stops, and due to gas leaking from line 11 into this cavity, the pressure in it rises, which leads to the closing of valve 14 and the opening of valve 15, the liquid begins to flow through valve 15 into source 13, cooling in heat exchanger 19.

Thus, in this design, there is an active circular movement of the coolant and intensive heat removal from the walls of cylinder 1.

The operating principle of the design shown in Fig. 7 is similar to that described above, except that a different part of the piston stroke during the suction process is used to activate the movement of the coolant.

When piston 4 moves from TDC towards BDC (Fig. 9), valve 23 is acted upon by the upward inertial force (the piston moves with acceleration). And when the pressure in cavity 3 becomes significantly lower than the pressure in line 11 (point b in Fig. 8), the sum of the inertial force and the force from the pressure drop on this valve exceed the force of its spring, and it opens, connecting cavity 22 with suction cavity 9 through open valve 7. Since the pressure in cavity 3 is minimal at this moment, gas from cavity 22 flows out through open valve 23 into cavity 3, and the pressure in cavity 22 actually becomes the same as in cavity 3.

In addition, as in the previous design, due to a drop in pressure in cavity 21, valve 14 opens and liquid from source 13 flows into cavity 21.

After the piston passes the middle of the path from TDC to BDC (Fig. 10), the direction of the inertial forces acting on valve 23 changes its direction, the pressure in cavity 3 increases somewhat (still remaining below the pressure in line 11), and valve 23, under the action of its spring and inertial forces, closes, maintaining a low pressure in cavity 22.

As in the previous design, when piston 4 approaches the BDC position (Fig. 11), valve 7 closes, and gas flows through valve 20. In this case, the outlet of channel 16 coincides with opening 24 of cavity 22, in which the pressure is much lower than the pressure of line 11, as a result of which there is a sharp decrease in pressure in cavity 21, which leads to continued flow of liquid through valve 14 into cavity 21.

Further, as in the previous design, during the piston's upward stroke, due to the fact that the opening 24 is disconnected from the channel 16, the pressure in the cavity 21 rises due to the gas flowing into it under the suction pressure from the line 11, the valve 14 closes, and the liquid flows through the jacket 2 into the source 13 through the valve 15, cooling in the heat exchanger 19.

In this design, in cavity 22, periodically on the part of the piston stroke connecting with the suction cavity 9, the lowest possible pressure is constantly formed, which makes it possible to intensify the circular movement of the cooling liquid through the jacket 2.

In the designs shown in Fig. 13 and 14, the intensification of the movement of liquid in the cooling system is also organized by temporarily connecting the suction cavity 9 with the cavity 3 through the open suction valve 7. This occurs as follows.

When the drive shaft 5 rotates, the flange 29 fixed in a certain position by the lock 30 rotates together with it. A permanent magnet 28 is installed on this flange, when it passes by the fixed coil 27, a surge of electric current is induced in it, which is fed to the coil 31. In this case, the coil 31 creates a short-term magnetic field, drawing in the anchor in the form of a valve 25, which overcomes the force of the return spring 31 and partially interrupts the suction line 11. This action occurs in the period of time when the piston 4 approaches the BDC position, and when the channel 6 connects the working cavity of the cylinder with the suction cavity 9.

Due to the fact that partial blocking of line 11 is accompanied by a drop in pressure in cavity 9, the supply of liquid through valve 14 into cavity 21 is intensified.

Subsequently, the magnetic field pulse ceases, and the shutter 25, under the action of the spring 33, returns to its original position.

In the design, the diagram of which is shown in Fig. 14, the movement of the valve 35, which is spring-loaded by the return spring 37, is organized by the cam 34 through the rod 36. The cam has a profile that ensures partial overlap of the line 11 at the moment when the piston 4 approaches the BDC position.

The proposed method and its implementation in the form of design solutions allows to significantly reduce the weight and size parameters of a compressor with autonomous cooling due to a more compact arrangement of the operating distribution elements within the cylinder-piston group, to increase the efficiency of operation due to more intensive movement of liquid in the cooling system, which allows to bring the process of gas compression closer to the most economical - isothermal.

Intensification of the cooling process also allows stabilizing the temperature of the cylinder-piston group (CPG) parts and thereby reducing the dead volume, which is determined both by the technological capabilities of the manufacturer and, to a large extent, by temperature changes in the CPG parts during their heating during compressor operation. Reducing the dead volume allows increasing the efficiency, performance, and maximum pressure increase coefficient (the ratio of the discharge pressure to the suction pressure) in one stage.

More reliable organization of liquid movement through the jacket also makes it possible to expand the range of compressor operating frequencies, especially in the direction of increasing the frequency, which also improves the weight and size indicators.

In connection with the above, it should be recognized that the set technical tasks have been fully accomplished.

Claims (6)

1. A method for autonomous cooling of a piston compressor, in which the cooling liquid located in the jacket of a cylinder containing a piston and a working cavity is pumped due to the pressure difference between the suction cavity and the surrounding environment, characterized in that the suction cavity is connected to the lower part of the working cavity of the cylinder through an intermediate cavity along a portion of the suction stroke when the piston is in the bottom dead center position. 2. A piston compressor with independent cooling, comprising a cylinder with a cooling jacket, a working cavity and a piston with a drive, a drive shaft and a mechanism for converting the rotary motion of the shaft into a reciprocating motion of the piston, suction and discharge valves installed in the suction and discharge cavity and connecting the working cavity of the cylinder with the suction and discharge lines, wherein the cooling jacket is connected to a source of coolant by means of suction and discharge valves, characterized in that the suction cavity on part of the suction stroke is connected by a channel through an intermediate cavity with the lower part of the working cavity of the cylinder when the piston is in the position of the bottom dead center. 3. A compressor according to item 2, characterized in that the piston contains a cavity equipped with a check valve connecting this cavity with the working cavity of the cylinder, and an opening towards the side surface of the cylinder, coinciding with the channel when the piston is in the position of the bottom dead center. 4. A compressor according to item 2, characterized in that the suction line is equipped with a valve connected to the drive shaft via a mechanism for moving it, made of a cam or electromagnetic type. 5. A compressor according to item 4, characterized in that the electromagnetic-type mechanism contains an inductor consisting of a fixed inductance coil and an anchor in the form of a permanent magnet fixed on the drive shaft with the ability to pass by the inductance coil with a small gap, and the inductance coil is connected to the coil of an electromagnet, the anchor of which is a damper. 6. A compressor according to item 4, characterized in that the cam-type mechanism contains a cam, kinematically or directly connected to the drive shaft with the ability to act on the damper.