JPH04116276A - Oil infiltration preventing device for heat-driven engine - Google Patents

Abstract

PURPOSE:To improve the oil infiltration prevention performance by setting the diameter of a cross head larger than the diameter of a power piston, and communicating the inner space of a crank case and the upper space of the cross head via a check valve and an oil separator. CONSTITUTION:The diameter phiD1 of a power piston 6 is set smaller than the diameter phiD2 of a cross head 8. When an engine is operated, the pressure Pd in the upper space 24 of the cross head 8 and the pressure Pb in the inner space 25 of a crank case are changed respectively. A check valve 28 is installed in the middle of a communicating pipe 26 between the upper space 24 of the cross head 8 and the inner space 25 of the crank case, thus the differential pressure is applied to the cross head 8 by the sucking effect of gas due to the pressure fluctuation of the inner space 25 of the crank case caused by the reciprocating movement of the cross head 8. The oil existing on the sliding face of the cross head 8 and scraped by the reciprocating movement of the cross head 8 is returned to the inner space 25 of the crank case by this differential pressure.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is directed to heat-driven engines such as Stirling engines and non-lubricated compressors, in which lubricating oil in the motion mechanism intrudes into the working space in the cylinders of those engines. This invention relates to an oil intrusion prevention device for a thermally driven engine that prevents oil ingress from occurring.

[Conventional technology]

Figure 13 shows, for example, European Patent No. 0212844 and Japanese Unexamined Patent Publication No. 6
This shows a conventional oil intrusion prevention device for a displacer-type Stirling engine disclosed in Publication No. 4-53049. In FIG. In addition to the effects of the heat exchanger 3, the regenerative heat exchanger 4, and the cooler 5, pressure fluctuations are generated within the cylinder.

Reference numeral 6 designates a power piston that receives pressure changes generated within the cylinder 2 and generates changes in piston load in accordance with the pressure changes, and connected to this are a power rod 7, a crosshead 8, a power connecting rod 9a, 9b, for transmitting motion with the crankshaft lO and obtaining rotational output to the outside.

A displacer connecting rod 11 is rotatably connected to the crankshaft 10, and a displacer rod 12 is connected to the other end of the connecting rod 11. Reference numeral 13 denotes a seal that maintains the airtightness of the crosshead 8 through which the displacer rod 12 passes and the portion through which the power piston 6 passes, and this seal 13 is usually made of various types of packing such as an O ring.

14 is a guide ring attached to the displacer 1; 15 is a bearing between the crosshead 8 and the power condo 1; the displacer 1 is supported by the guide ring 14 and also supported by the bearing 15 via the displacer rod 12; has been done.

Reference numeral 16 denotes a crankcase, and 17 denotes lubricating oil collected at the bottom of the crankcase 16. Inside this crankcase 16, oil particles are scattered as the crankshaft 10 rotates. For this reason, lubricating oil 17 is sent to the sliding surfaces of crankshaft 10, crosshead 8, and bearing 15 to provide a lubricating effect.

FIG. 14 is a schematic cross-sectional view showing a conventional oil intrusion prevention device for a heat-driven engine having a crosshead structure as disclosed in, for example, Japanese Patent Application Laid-Open No. 56-38543. In FIG. 14, in which redundant explanation has been omitted, 20a to 20C are gasket-like rod seals installed in the cylinder so as to slide airtightly on the cylindrical surface of the piston rod, and 21 is a sliding seal of the crosshead 8. This is an oil recovery mechanism section that recovers oil separated by the surfaces and rod seals 20a and 20b.

FIG. 15 is a cross-sectional view of a main part of a crosshead upper structure showing another conventional oil intrusion prevention device for a heat-driven engine having a crosshead structure as disclosed in, for example, Japanese Unexamined Patent Publication No. 64-49798. In FIG. 15, in which the same parts as those in FIG. Both piston rings 2223 have a pressure sealing function.

24 is a space between the power piston 6 and the crosshead 8;
That is, the crosshead upper space, 25 is the crankcase internal space, 26 is a communicating pipe that communicates the crosshead upper space 24 and the crankcase internal space 25, and 27 is the communicating pipe 26.
The oil separator 28 is a check valve installed in the middle of the communication pipe 26, and as shown in the figure, the oil separator 28 is a check valve installed in the middle of the communication pipe 26, and as shown in the figure, the oil separator 28 is a check valve that allows gas to flow from the bottom to the top, that is, from the crankcase internal space 25 to the crosshead upper space 24. Flow only in the direction.

Pd represents the pressure change in the crosshead upper space 24, and pb represents the pressure change in the crankcase internal space 25 due to operation (reciprocating movement of the rad 8 to the crosshead). Pd exhibits a constant pressure because there is no volume change in the space 24 above the crosshead, and pb
, a volume change occurs in the crankcase internal space 25, and the first
As shown in FIG. 6 or FIG. 17, pressure changes occur depending on the crank angle.

In other words, by utilizing the pressure fluctuations in the crankcase internal space 25 that occur with the reciprocating motion of the crosshead 8 and pumping up the dry gas in the crankcase internal space 25 to the crosshead upper space 24, the crosshead upper space A pressure difference can be created between 24 and the crankcase interior space 25.

That is, due to the effect of the check valve 28, there are many situations where Pd>Pb. If there is no check valve, the pressure state is
The result will be as shown in Figure 7. This pressure difference pushes back the lubricating oil present on the crosshead sliding surface, which has been scraped up by the reciprocating motion of the crosshead 8, toward the crankcase, thereby preventing the oil from entering the working space 19 in the cylinder 2.

[Problem to be solved by the invention]

Since the conventional oil intrusion prevention device for a thermally driven engine is constructed as described above, the oil that lubricates the sliding surface of the crosshead 8 is scattered in the direction of the power piston 6 above the sliding surface. Therefore, in the conventional device shown in FIG. 13, rod seals 20a to 20C are provided in order to directly scrape off oil from the crosshead sliding surface, but these rod seals generally have a strong tension and cause friction. The losses are excessive and there is a need for improvement.

Furthermore, in the conventional device shown in FIG.
When the volume of the crosshead 6 is large, the rate of volume change due to the reciprocation of the crosshead 8 is also relatively small.

As a result, the pressure change value of Pb that occurs becomes small, and the differential pressure (pa-pb) becomes small. There was a problem that the performance of preventing oil intrusion into the working space 19 deteriorated.

This invention was made to solve the above-mentioned problems, and its purpose is to improve oil intrusion prevention performance.

[Means to solve the problem]

In the oil intrusion prevention device for a thermally driven engine according to the invention of claim (1), the diameter of the crosshead is formed to be larger than the diameter of the piston.

The oil intrusion prevention device for a thermally driven engine according to the invention of claim (2) includes sealing members provided in two stages, upper and lower, on the crosshead so as to seal between the crosshead upper space and the crankcase internal space; A communication hole is provided that communicates the space between the upper seal member and the lower seal member with the crankcase interior space.

The oil intrusion prevention device for a heat-driven engine according to the invention of claim (3) is provided in three stages of upper, middle, and lower stages of the crosshead so as to seal between the upper space of the crosshead and the internal space of the crankcase. a sealing member, a first communication hole that communicates a space between the upper sealing member and the middle sealing member with the crankcase internal space, and a space between the middle sealing member and the lower sealing member; A second communication hole communicating with the crosshead upper member space is provided.

The oil intrusion prevention device for a thermally driven engine according to the invention of claim (4) includes a sealing member provided on the crosshead to seal between the crosshead upper space and the crankcase internal space; It is equipped with an oil-absorbing resin that changes its volume depending on the amount of oil absorbed in the space.

The oil intrusion prevention device for a thermally driven engine according to the invention of claim (5) includes a first seal member provided on the crosshead, and a gas leak resistance provided on the piston that is smaller than the gas leak resistance of the first seal member. A second seal member is provided, and the working space in the cylinder and the internal space of the crankcase are communicated through a communication pipe having a check valve and an oil separator.

[For production]

In the invention of claim (1), the pressure in the crosshead upper space is opposite to the pressure in the crankcase internal space in that the maximum value and minimum value of the pressure amplitude occur, so the differential pressure of repressure is large. , the force pushing back oil present on the crosshead sliding surface increases, improving oil intrusion prevention performance.

Since the differential pressure in the invention of claim (2) or claim (3) occurs in two or more stages, the oil intrusion prevention performance should not be degraded even if the pressure fluctuation in the internal space of the crankcase is small. .

The oil-absorbing resin in the invention of claim (4) changes the pressure in the space above the crosshead by expanding its volume in accordance with the amount of oil absorbed, so the differential pressure acting on the top of the crosshead changes. The sealing member according to the invention of claim (5), characterized in that oil does not infiltrate into the working space of the cylinder, has a gas leakage resistance of the sealing member provided on the piston that is smaller than gas leakage resistance of the sealing member provided on the crosshead. By communicating the working space of the cylinder and the internal space of the crankcase through a communication pipe equipped with a check valve and an oil separator, the differential pressure acting on the seal member provided on the crosshead increases, improving oil intrusion prevention performance. will improve.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view of essential parts showing an embodiment of the inventive device according to claim (1), and in FIG. 1, the same parts as in FIG. 6
The diameter φD of the crosshead 8 is smaller than the diameter φD2 of the crosshead 8.

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

When the engine is operated, the pressure Pd in the crosshead upper space 24 and the pressure Pb in the crankcase internal space 25 are as follows.
Each changes.

For example, when the crosshead 8 is at the top dead center, the volume within the crosshead upper space 24 is at its minimum, and the pressure pb within the crosshead upper space 24 is at its maximum value. On the contrary, the volume within the crankcase internal space 25 is at its maximum value, and the pressure Pb within the crankcase internal space 25 is at its minimum value. This situation is shown in FIGS. 2 and 3. If the check valve 28 is not installed in the middle of the communication pipe 26 between the crosshead upper space 24 and the crankcase internal space 25, the average value of the pressures of both will be at the same level, but the check valve 28 should be installed. The pressure relationship shown in FIG. 3 is achieved due to the gas pumping effect caused by pressure fluctuations in the crankcase internal space 25 that occur as the crosshead 8 reciprocates.

As a result, a differential pressure (Pd-Pb) acts on the crosshead 8, and the oil present on the crosshead sliding surface, which is scraped up by the reciprocating motion of the crosshead 8, is removed from the crankcase internal space 25 by the differential pressure. be pushed back to The differential pressure is greater than the differential pressure of the conventional device by the amount ΔPd by which Pd fluctuates.

FIG. 4 is a sectional view of essential parts showing an embodiment of the inventive device of claim (2), and FIG. 5 is a bottom view of the crosshead.
8a in FIGS. 4 and 5, in which the same parts as in the figures are given the same reference numerals and redundant explanations are omitted.

8b is a blind hole 29a formed in the bottom surface of the crosshead 8 so that the connecting rods 9a and 9b can be inserted.
, 29b are sealing members provided in two stages, upper and lower, on the crosshead 8, and 30 is a sealing member 29a.

A space formed between 29b and the inner wall of cylinder 2, 3
Reference numeral 1 denotes a communication hole that communicates the space 30 with the crankcase internal space 25 via the blind holes 8a and 8b.

As mentioned above, when the seal members are installed in two stages, upper and lower, on the crosshead 8, the oil that is scraped up by the reciprocating movement of the crosshead and stays on the crosshead sliding surface is evacuated by the pressure difference 2X (Pd-Pb ) is pushed back into the crankcase internal space 25, and even when pressure fluctuations in the crankcase internal space are small, sufficient oil intrusion prevention performance can be obtained.

Note that a differential pressure acts on the seal member 29b from the bottom to the top (from the space 25 to 30), and oil is pumped up, but the space 30 is communicated with the crankcase internal space 25,
There is no particular problem as the oil will return.

6 and 7 are sectional views of essential parts showing an embodiment of the inventive device according to claim (3), and FIG. 8 is a bottom view of the crosshead,
In FIGS. 6 to 8, in which the same parts as in FIG. and the cylinder inner wall, the sealing member 32
A space 33.34 is formed between the seal member 32b and the seal member 32b and between the seal member 32b and the seal member 32C. 35 is a communication hole that communicates the crankcase internal space 25 and the space 33;
36 is a communication hole that communicates the crosshead upper space 24 and the space 34.

The three upper and lower seal members 32a to 32c and the communication hole 35
．． 36, a pressure difference of 2 (Pd-Pb) or more is generated between the crosshead upper space 24 and the crankcase internal space 25. As a result, the oil on the crosshead sliding surface that is scraped up by the reciprocating motion of the crosshead 8 is pushed back into the crankcase internal space by the differential pressure.

In this case, the differential pressure acts on the middle seal member 32b from the bottom to the top (from the space 34 to the space 33), and oil is pumped up, but the space 33 is the inner space of the crankcase 2.
5, and oil flows into the crankcase internal space 25.
, so there is no particular problem.

FIG. 9 is a cross-sectional view of essential parts showing an embodiment of the inventive device according to claim (4). In FIG. 9, the same parts as those in FIG. The oil-absorbing resin is installed in the crosshead upper space 24, and in the illustrated example, it is provided on the inner wall surface of the cylinder 2, the surfaces of the power piston 2 and the crosshead 8, and the surface of the rod 7 that connects the two.

As this oil-absorbing resin 38, for example, a "highly oil-absorbing resin" developed and announced by Nippon Shokubai Kagaku Kogyo Co., Ltd. is used. When this oil-absorbing resin 38 comes into contact with an oil component, it absorbs the oil component inside the resin molecule and the resin itself expands.
This expansion changes the pressure in the crosshead upper space 24, and the differential pressure caused by this pressure change prevents oil from entering the working space of the cylinder 2.

FIG. 10 is a cross-sectional view of essential parts showing an embodiment of the inventive device according to claim (5). In FIG. 10, the same parts as those in FIG. This is a communication pipe that communicates the working space 19 in the cylinder 2 with the crankcase internal space 25, and there is an oil separator 40 in the middle of this communication pipe 39, and gas flows from the crankcase internal space 25 to the working space 19 of the cylinder 2. A check valve 41 is provided.

In this case, the sealing member (piston ring) 42 provided on the power piston 6 is set to have a lower leakage resistance than the sealing performance of the sealing member (piston ring) 43 provided on the crosshead 8. The leakage resistance can be made relatively small by increasing the leakage area or by relatively reducing the number of stages in which the seal member 42 is mounted.

As a result, the average pressure in the crosshead upper space 24 is approximated to the pressure in the working space 19 in the cylinder 2, which has relatively low leakage resistance.

Fig. 11 is a pressure change diagram in which the horizontal axis represents the rotational crank angle of the crankshaft and the pressure represents the thin axis.
Pressure change due to engine operation in the working space 19 within the P
b shows the pressure change in the crankcase internal space 25, and Pc shows the average value of the cylinder pressure.

If the embodiment shown in FIG. 10 is configured, the relationship between pressure Pd and pressure Pb will be as shown in FIG. 12 due to the effect of the check valve 30 and the difference in sealing performance between the power piston 2 and the crosshead 8. . Here, the pressure Pd is approximately at the same level as the average pressure Pc inside the cylinder, so the differential pressure (Pd-Pb
) becomes large, improving oil intrusion prevention performance.

〔Effect of the invention〕

As described above, according to the invention of claim (1), the diameter of the crosshead is set larger than the diameter of the power piston, and the internal space of the crankcase and the upper space of the crosshead are connected to the check valve.
By communicating through the oil separator and increasing the differential pressure applied to the cross head Rad Seal, the oil scraped up by the reciprocating movement of the cross head is pushed back into the crankcase internal space by the above differential pressure, and the cross head This makes it difficult for oil to enter the upper space, improving oil intrusion prevention performance.

According to the invention of claim (2) or (3), the crosshead is provided with seal members in two upper and lower stages or in three upper, middle, and lower stages, and the space between the seal members is communicated with the crankcase internal space, In addition, since it is configured to communicate with the space above the crosshead at the same time, a pressure difference of two or more stages acts on these seal members, and the oil scraped up by the reciprocating movement of the crosshead is removed from the inside of the crankcase. Push back into space.

As a result, the oil intrusion prevention performance is improved, and even when the crankcase internal pressure fluctuation is small, the oil intrusion prevention performance does not deteriorate.

According to the invention of claim (4), the oil component that has entered the space above the crosshead is adsorbed by the oil-absorbing resin, and the oil-absorbing resin expands according to the amount of adsorption, thereby reducing the pressure in the space above the crosshead. This increases the differential pressure and pushes the oil back into the internal space of the crankcase, improving the function of preventing oil from entering the working space of the cylinder.

According to the invention of claim (5), the gas leakage resistance of the seal member provided on the crosshead is made greater than the gas leakage resistance of the seal member of the power piston, and the internal space of the crankcase and the working space within the cylinder are separated by a check valve. , the pressure in the upper space of the crosshead approximates the average pressure in the working space in the cylinder by communicating through an oil separator, which increases the differential pressure acting on the sealing member of the crosshead and prevents oil intrusion. Prevention performance is improved.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a main part showing an embodiment of the invention device of claim (1), and Figs. 2 and 3 show pressure changes in the crosshead upper space and crankcase internal space during engine operation of this invention device. Figure 4 is a sectional view of a main part showing an embodiment of the inventive device of claim (2), Figure 5 is a bottom view of the crosshead, and Figures 6 and 7 are the inventive device of claim (3). 8 is a bottom view of the crosshead in this device, FIG. 9 is a sectional view of essential parts showing an embodiment of the inventive device of claim (4), and FIG. 11 and 12 are cross-sectional views of the main parts showing the embodiment of the inventive device of item (5), and FIG. 13 is a diagram of pressure changes in the crosshead upper space and crankcase internal space during engine operation of this inventive device. to 15th
The figures are longitudinal sectional views showing various conventional devices, Figs. 16 and 17.
The figure is a pressure change diagram during engine operation of a conventional device. 6 is a piston, 7 is a rod, 8 is a crosshead, 10 is a crankshaft, 11 is a connecting rod, 24 is a crosshead upper space, 25 is a crankcase internal space, 2
6.39 is a communication pipe, 27.40 is an oil separator, 28.41
are check valves, 29a, 29b, 32a to 32c, 42.
43 is a sealing member, 30.33.34 is a space, 31,3
5.36 is a communication hole, and 3rd is an oil-absorbing resin. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (5)

[Claims] (1) A crankshaft for converting rotational motion into reciprocating motion, a crosshead connected to this crankshaft via a connecting rod, a piston connected to this crosshead via a rod, and a lower part of the crosshead. A communication pipe that communicates the crankcase internal space and the crosshead upper space, a check valve that is provided in the middle of the communication pipe and whose flow direction is from the crankcase internal space to the crosshead upper space, and a an oil separator that separates a lubricating oil component; and a sealing member provided on the crosshead to seal between the crosshead upper space and the crankcase internal space; An oil infiltration prevention device for thermally driven engines formed with a dimension larger than the diameter of. (2) A crankshaft for converting rotational motion into reciprocating motion, a crosshead connected to this crankshaft via a connecting rod, a piston connected to this crosshead via a rod, and a lower part of the crosshead. A communication pipe that communicates the crankcase internal space and the crosshead upper space, a check valve that is provided in the middle of the communication pipe and whose flow direction is from the crankcase internal space to the crosshead upper space, and a an oil separator that separates lubricating oil components; a seal member provided in two upper and lower stages on the crosshead to seal between the crosshead upper space and the crankcase internal space; the upper seal member and the lower seal member; An oil intrusion prevention device for a thermally driven engine, comprising a communication hole that communicates a space between the seal member and the crankcase interior space. (3) A crankshaft for converting rotational motion into reciprocating motion, a crosshead connected to this crankshaft via a connecting rod, a piston connected to this crosshead via a rod, and a lower part of the crosshead. A communication pipe that communicates the crankcase internal space and the crosshead upper space, a check valve that is provided in the middle of the communication pipe and whose flow direction is from the crankcase internal space to the crosshead upper space, and a an oil separator that separates a lubricating oil component; a sealing member provided in three stages of upper, middle, and lower stages of the crosshead to seal between the upper space of the crosshead and the internal space of the crankcase; and the upper stage. a first communication hole that communicates a space between the seal member and the middle seal member with the crankcase internal space; a space between the middle seal member and the lower seal member and the crosshead upper space; and a second communication hole communicating with the oil intrusion prevention device for a thermally driven engine. (4) A crankshaft for converting rotational motion into reciprocating motion, a crosshead connected to this crankshaft via a connecting rod, a piston connected to this crosshead via a rod, and a lower part of the crosshead. A communication pipe that communicates the crankcase internal space and the crosshead upper space, a check valve that is provided in the middle of the communication pipe and whose flow direction is from the crankcase internal space to the crosshead upper space, and a an oil separator that separates lubricating oil components; a seal member provided on the crosshead to seal between the crosshead upper space and the crankcase internal space; and an oil absorber installed in the crosshead upper space. An oil intrusion prevention device for thermally driven engines equipped with an oil-absorbing resin whose volume changes depending on the amount of oil. (5) A crankshaft for converting rotational motion into reciprocating motion, a crosshead connected to this crankshaft via a connecting rod, a piston connected to this crosshead via a rod, and a lower part of the crosshead. A communication pipe that communicates the internal space of the crankcase with the working space in the cylinder, a check valve that is provided in the middle of the communicating pipe so that the flow direction is from the internal space of the crankcase to the working space, and lubricating oil in the working fluid. an oil separator for separating components; a first seal member provided on the crosshead; and a second seal member provided on the piston and having a gas leakage resistance smaller than that of the first sealing member. Oil intrusion prevention device for heat-driven engines.