JPH0723704B2 - Oil entry prevention structure for Stirling engine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a structure for preventing oil lubricating a sliding portion of a bearing portion of a displacer rod of a Stirling engine from entering an operating space. .

[Conventional technology]

FIG. 7 is a sectional view showing a conventional displacer type Stirling engine disclosed in, for example, Japanese Patent Laid-Open No. 60-212660. In the figure, 1 is a displacer,
The high pressure working fluid in the cylinder 2 is caused to flow to the heater.
3, in addition to the functions of the regenerative heat exchanger 4 and the cooler 5, a pressure change is generated in the cylinder. Reference numeral 6 is a power piston for taking out a pressure change generated in the cylinder as an output, and a power rod 7 and a crosshead connected to the power piston.
8, Power is transmitted to the connecting rods 9a, 9b, crankshaft 10,
It is for obtaining the rotation output to the outside. Crankshaft 10
Further, a displacer connecting rod 11 is rotatably connected to the displacer connecting rod 11, and a displacer rod 12 is connected to the other end of the connecting rod 11.
Penetrates the crosshead 8 and the power piston 6 and transmits the motion to the displacer 1. 13 is the displacer rod
With a shaft seal that keeps the 12 power piston 6 penetrations airtight,
Various packings such as O-rings are usually used. Reference numeral 14 is a guide ring attached to the displacer 1, and 15 is a bearing between the crosshead 8 and the power rod 7. The displacer 1 is supported by the guide ring 14 and also by the bearing 15 via the displacer rod 12. Has been done. Reference numeral 16 is a crankcase, and 17 is a lubricating oil on the bottom of the crankcase. The lubricating oil 17 is sent to the sliding surfaces of the crankshaft 10, the crosshead 8 and the bearings 15 for lubrication.

[Problems to be solved by the invention]

In the Stalin engine having such a configuration, the lubricating oil that lubricates the bearing 15 of the displacer rod 12 enters the upper portion of the bearing 15 as the power piston 6 and the displacer 1 reciprocate vertically. Further, it enters the gap 18 between the power rod 7 and the displacer rod 12 as droplets, adheres to the shaft seal 13 and enters the working space 19 above the power piston 6. As a result, the invading lubricating oil adheres to the heater 3, the regenerative heat exchanger 4, and the cooler 5, and deteriorates the performance of the Stirling engine.

The present invention has been made to solve the above problems, and an object of the present invention is to obtain an oil intrusion prevention structure for a Stirling engine that prevents invasion of lubricating oil from above the bearing.

[Means for solving problems]

The oil intrusion prevention structure of the Stirling engine according to the present invention,
The crosshead sliding part and the displacer rod bearing sliding part have a sealing function, the upper and lower spaces of the crosshead are connected by a valve mechanism, and the average pressure in the upper space of the crosshead is made relatively high. The power rod is provided with a vent hole communicating with the inside of the power rod.

[Action]

In the present invention, the average pressure in the upper space of the displacer rod bearing becomes higher than the average pressure in the crankcase, and the lubricating oil mechanically pumped up by the reciprocating motion of the displacer rod is pushed back by the differential pressure to operate. Inhibits lubricant from entering the space.

〔Example〕

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

FIG. 1 shows an oil intrusion prevention structure for a Stirling engine according to an embodiment of the present invention, in which 31 is a crosshead 8
The inner space of the crankcase formed by the lower part of the and the crankcase 16, 32 is the crosshead 8, power piston 6, cylinder 2
Is the upper space of the crosshead formed by. The volume of the crosshead upper space 32 is configured such that the amount of change is small or does not exist even when the crosshead 8 and the displacer rod 12 reciprocate. 33 is a ventilation pipe (communication pipe) that connects the spaces 31 and 32, and an oil mist separator is provided in the middle of the pipe.
34 and a check valve 35 whose flow direction is the direction of the arrow in the figure are arranged. 36 is a vent hole provided in the power rod 7, and a gap between the power rod 7 and the displacer rod 12
The space 18 communicates with the upper space 32 of the crosshead. Reference numeral 37 denotes a sliding portion of the crosshead 8 and 38 denotes a sliding portion of the displacer rod bearing portion, which have lubricating oils permeated therein and have a sealing function.

Next, the function and effect will be described.

Normally, this Stirling engine is operated while the inside of the crankcase is pressurized. The crosshead 8 and the power piston 6 repeat up and down and reciprocating movements in synchronization with the rotation of the crankshaft. At this time, since the volume of the crankcase inner space 31 changes as the crosshead 8 reciprocates, its pressure also changes. However, the pressure of the crosshead upper space 32 shows a substantially constant value because the volume change is small and the amount of gas leakage from the working space 19 is usually small.

Now consider the case where the vent tube is blocked. In this case, if the sliding surface 37 of the crosshead 8 is well sealed, the pressure Pb in the crankcase inner space 31 and the pressure Pd in the crosshead upper space 32 are increased.
Are usually observed as shown in FIG. That is, the average pressures of the two pressures Pb and Pd are almost equal.

Next, consider the case where the piping shown in FIG. 1 is provided. When the crosshead 8 is below the reciprocating section, Pb is higher than Pd and is in the range shown by A in FIG. During this time period, gas is sucked into the crosshead upper space 32 from the crankcase inner space 31 through the check valve 35. That is, by providing the check valve 35, the space 31 has a function equivalent to that of the compressor. In this case, the relationship between Pb and Pd is as shown in FIG. 3, and the average pressure of Pd is Pb. Higher than the average pressure of. Since the oil mist separator 34 is attached to the ventilation pipe 33, the lubricating oil mist contained in the gas flowing from the crankcase inner space 31 is separated, and only the dry gas flows into the crosshead upper space 32. Will be done.

As is well known here, the lubricating oil such as the bearing of the crankshaft scatters, passes through the bearing gap 38 and enters the gap 18. The reciprocating motion of the displacer rod 12 in the lubricated state causes the lubricating oil on the sliding surface 38 to be pumped up by an amount substantially proportional to the rotational speed of the engine. Originally, the lubricating oil pumped up in this way penetrates into the working space through the gap 18, causing various inconveniences. However, as in the present embodiment, by providing a check valve mechanism between the upper space 32 of the crosshead and the crankcase inner space 31, the pressure in those spaces 31, 32 is controlled, and further, inside the power rod. By communicating the gap 18 with the cross head upper space 32 through the vent hole 36, the pressure relationship between the upper and lower spaces of the bearing 15 of the displacer rod 12 can be controlled as shown in FIG. By maintaining such a pressure relationship, the lubricating oil 17 pumped up through the sliding surface 38 of the bearing 15 of the displacer rod 12 is pumped up by the pressure difference (Pd−Pb) between the crankcase inner space 31 and the crankcase 16 Can be pushed back to the bottom of.

As described above, in the present embodiment, the pressure between the upper and lower portions of the crosshead 8 is controlled as shown in FIG. 3, so that the mechanically pump-amplified oil has a pressure difference (Pd−Pb). ,
Backflow to the crankcase inner space 31 side under the crosshead. That is, the lubricating oil that flows into the gap 18 and the working space 19 through the bearing sliding gap 38 of the displacer 12 is suppressed, and the amount of oil intrusion becomes a minute amount.

Next, another embodiment will be described. 4 and 5 show the crosshead upper space 32 and the crankcase inner space 31.
As a method of controlling the pressure of the above, a valve mechanism is arranged on the crosshead 8. In FIG. 4, 40 is a valve mechanism mounted on the crosshead 8. The details are shown in FIG. 5, 41 is a vent hole processed in the crosshead 8, 42 is a flexible valve plate made of a thin plate, and opens and closes the vent hole 41. 43 is a valve stopper that restricts the movement of the valve plate 42, 44 is a screw or rivet that fixes the valve plate 42 and the valve stopper 43 to the crosshead, and 45 is an oil mist separator that allows the spray of the lubricating oil 17 and mist to pass through. It is intended to prevent entry into the upper space 32 of the crosshead through the pores 41.

Thus, even if the crosshead 8 is provided with a check valve mechanism,
The pressure relationship shown in FIG. 3 can be established, and the same effect as that of the above embodiment can be obtained.

Next, still another embodiment of the present invention will be described. Sixth
The figure shows an example in which a piston ring 46 is mounted on the crosshead 8 and a piston ring 47 is mounted on the bearing surface of the displacer rod 12 to improve the sealing function of each sliding surface. With such a structure, the pressure control shown in FIG. 3 becomes easier than in the case of the embodiment shown in FIG.

In the embodiment shown in FIG. 6, an oil splash prevention plate 48 made of a porous object (sponge or foam metal) is provided, which allows the lubricating oil to pass through the bearing gap 38 and rise to the upper portion of the bearing. Also, the lubricating oil can be prevented from scattering upward, and the oil can be prevented from adhering to the shaft seal 13. Thereby, the effect of the present invention can be further improved.

〔The invention's effect〕

As described above, according to the present invention, the upper and lower spaces of the crosshead are communicated with each other by, for example, a check valve, an oil separator, etc., and the crosshead upper space average pressure is set higher than the lower space crankcase pressure. Since the space above the crosshead communicates with the space inside the power rod, the amount of lubricating oil that enters from the bearing of the displacer rod and rises inside the power rod can be pushed back by the above pressure difference, and lubrication to the working space, etc. It has the effect of preventing oil from entering. Further, if an oil splash prevention plate is provided above the bearing portion of the displacer rod, and a piston ring is provided on the crosshead and displacer, the oil splash prevention effect can be further improved.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an oil intrusion prevention structure for a Stirling engine according to an embodiment of the present invention, and FIGS. 2 and 3 show pressure conditions during operation of the engine in the crosshead upper space and the crankcase inner space. FIGS. 4 and 6 are schematic sectional views showing other embodiments of the present invention, and FIG. 7 is a schematic sectional view showing a conventional oil intrusion prevention structure. 1 ... Displacer, 2 ... Cylinder, 6 ... Power piston, 7 ... Power rod, 8 ... Crosshead, 12 ...
… Displacer rod, 15 …… Bearing, 16 …… Crankcase, 31 …… Crankcase inner space, 32 …… Crosshead upper space, 33 …… Ventilation pipe, 34 …… Oil mist separator,
35 …… Check valve, 36 …… Vent hole, 40 …… Valve mechanism, 41 …… Vent hole, 42 …… Valve plate, 43 …… Valve stopper, 44 …… Bolt,
45 …… Oil mist separator, 46, 47 …… Piston ring, 48
...... Oil splash prevention plate. The same reference numerals in the drawings indicate the same or corresponding parts.

 ─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-61-187565 (JP, A) JP-A-59-85457 (JP, A) JP-B-49-2204 (JP, B1)

Claims (7)

[Claims] 1. A displacer that reciprocally slides in a cylinder to generate a pressure change in the cylinder, a displacer rod connecting the displacer and a crank mechanism, and a through hole into which the displacer rod is inserted.
A power piston for taking out a pressure change generated in the cylinder as a mechanical output, fixed to the power piston via a power rod, connected to the crank mechanism, and reciprocally slides in the cylinder together with the power piston. In a Stirling engine equipped with a crosshead, even when the crosshead and the power piston are reciprocating, the intermediate space between the power piston and the upper part of the crosshead does not change in volume, or its rate of change is small. And the crankcase inner space at the lower part of the crosshead and the upper space of the crosshead are communicated with each other through a check valve having the upper part as a flow direction from the lower part of the crosshead, and the displacer rod is inserted. The through hole in the center of the power rod and the space above the crosshead. A structure for preventing oil intrusion in a Stirling engine, characterized in that pores are formed in the power rod. 2. The crosshead upper space and the crankcase inner space are communicated with each other via a ventilation pipe, and the check valve and the oil mist separator are provided in the middle of the pipe line of the ventilation pipe. An oil intrusion prevention structure for a Stirling engine as set forth in claim 1, wherein: 3. The upper space of the crosshead and the inner space of the crankcase are communicated with each other by a vent hole formed in the crosshead, and the check valve is provided at one end of the vent hole and the oil is provided at the other end. The oil intrusion prevention structure for a Stirling engine according to claim 1, wherein a mist separator is provided. 4. The check valve includes a valve plate having flexibility,
An oil intrusion prevention structure for a Stirling engine according to claim 3, wherein a valve stopper for limiting the movement of the valve plate is fixed to the crosshead. 5. The Stirling engine oil intrusion prevention structure according to any one of claims 1 to 4, wherein a piston ring is mounted on the crosshead. 6. A bearing portion for supporting the displacer rod is provided near the crosshead of the through hole into which the displacer rod is inserted, and a piston ring is mounted on the bearing portion of the displacer rod. An oil intrusion prevention structure for a Stirling engine according to any one of claims 1 to 5, wherein: 7. The oil intrusion prevention structure according to any one of claims 1 to 6, wherein an oil splash prevention plate is fixed to an upper portion of the bearing portion of the displacer rod.