JPH0317060B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD OF THE INVENTION The present invention relates to an adiabatic expansion engine of highly durable construction.

[Technical background of the invention and its problems]

Refrigerant in cryogenic refrigeration cycle, cold He
Adiabatic expansion engines are often used to cool gas. Figures 1a and 1b schematically show the main structure and operation of this type of adiabatic expansion engine. A cylinder 2 in which a piston 1 is reciprocably provided has an intake port 3 for high-pressure He gas at the bottom thereof, and an exhaust port 4 at the bottom wall thereof. The intake port 3 is provided with an intake valve 5 that closes the intake port 3 in response to the pressure of external high-pressure He gas. The protrusion 5a is pressed by the piston 1 to open the intake port 3 from the time when the piston approaches the piston to the time when the piston moves away from the piston by the above-mentioned first distance via the top dead center.

On the other hand, inside the cylinder 2, a movable body 6 is provided which can slide on the inner wall and move freely in the axial direction. This moving body 6 engages with the projection 1a of the piston 1 and moves toward the bottom of the cylinder 2 before the piston 1 approaches the first distance from the top dead center, and the piston 1 moves toward the bottom of the cylinder 2. Before reaching the bottom dead center, the piston 1 engages with the projection 1a of the piston 1 and moves in a direction away from the bottom side. In other words, the movable body 6 is hysteretically moved in accordance with the movement of the piston 1. A packing body 7 that closes the exhaust port 4 when moved toward the bottom of the cylinder is attached to the movable body 6. When the movable body 6 is pulled away from the bottom of the cylinder, the exhaust port 4 is unblocked by the packing body 7, that is, the exhaust port 4 is opened, and these constitute an exhaust valve. has been done.

Thus, in an adiabatic expansion engine equipped with such a valve mechanism, when the piston 1 is in the above-mentioned positional relationship with respect to top dead center, the intake valve 5 is opened and high-pressure He gas is introduced into the cylinder 1. As the piston 1 moves, the intake port 3 is closed again, and the introduced He gas is adiabatically expanded within the cylinder 2. Thereafter, when the piston 1 reaches the bottom dead center, the moving body 6 is pulled up to open the exhaust port 4, and as the piston 1 moves from the bottom dead center to the top dead center, the adiabatically expanded He The gas will be exhausted. Thus, one cycle of the adiabatic expansion engine ends here.

However, the conventional adiabatic expansion engine has the following problems. That is, the packing body 7 constituting the exhaust valve slides on the inner wall surface of the cylinder 2 as the piston 1 moves, that is, the movable body 6 moves. For this reason, there was a problem that the sliding surface of the packing body 7 was easily worn, and its durability was low. Furthermore, with the above configuration, the movable body 6 can easily slide on the inner surface of the cylinder 2,
This sliding movement also caused wear on the movable body 6.

[Purpose of the invention]

The present invention was made in consideration of these circumstances, and its purpose is to increase the durability of the structure without complicating it.
The object of the present invention is to provide an adiabatic expansion engine that can improve performance at the same time.

[Summary of the invention]

In order to achieve the above object, an expansion engine according to the present invention includes a cylinder having an intake port and an exhaust port on the bottom surface, a piston provided in the cylinder so as to be able to reciprocate, and a piston that normally closes the intake port. death,
Pressed by the piston to release the intake port from the time when the piston approaches the top dead center to a first distance to the time when the piston moves away from the top dead center to the first distance, an intake valve that introduces high-pressure gas into the cylinder; and an intake valve that is movably provided in the cylinder and that engages the piston before the piston approaches the first distance from the top dead center. a moving body that moves toward the bottom side of the cylinder, engages with the piston before the piston reaches bottom dead center, and moves away from the bottom side; In addition to supporting the peripheral surface without contacting it,
a spring member that selectively stabilizes the movable body in two stable positions in the axial direction by a reversing action in the axial direction;
A packing body is provided on the movable body and closes the exhaust port when the movable body is in a stable position on the bottom side of the cylinder among the two stable positions.

〔Effect of the invention〕

Thus, according to the embodiment, the packing body that closes the exhaust port on the bottom of the cylinder in response to the movement of the piston does not slide on the inner wall surface of the cylinder, so that it does not wear out. Therefore, the durability of the valve mechanism can be increased, and since the moving body is supported without contacting the inner peripheral surface of the cylinder using the spring member, sliding wear on the moving body can be prevented. This can also improve durability. Furthermore, since we use a spring member that has the function of selectively stabilizing the movable body in two stable positions in the axial direction by reversing the action in the axial direction, it is possible to prevent the intake valve from starting its opening operation. The timing can be set to rapidly and reliably close the exhaust port to coincide with the point in time.
Therefore, the dead space can be reduced and loss can be minimized, so that performance can be improved.

[Embodiments of the invention]

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

Figures 2a and 2b show the main structure and operation of the adiabatic expansion engine according to the embodiment, and the same parts as those of the conventional engine shown in Figure 1a and b are designated by the same reference numerals. There is. This engine is different from conventional engines in that the exhaust port 4 is provided at the bottom of the cylinder 2, and the movable body 6 to which the packing body 7 that closes the exhaust port 4 is attached is connected to the inner peripheral surface of the cylinder 2. receives the biasing force of the leaf spring 10 that is fixed to the inner wall surface of the cylinder 2 without contact, and engages with the protrusion 1a of the piston 1 to move to the cylinder bottom side or to a position away from the cylinder bottom surface. The point is that it is structured like this. The moving body 6 has a packing body 7 attached to the bottom surface of the cylinder at its tip, particularly at a position facing the exhaust port 4, and is provided so as to be freely movable in the axial direction inside the cylinder 2. Then, the movable body 6 engages its locking portion with the protrusion of the piston 1, and moves to the bottom side of the cylinder 1 as shown in FIG. 2b just before the piston 1 reaches the top dead center. Immediately before the piston 1 reaches the bottom dead center, it is moved to a position separated from the bottom surface of the cylinder 1, as shown in FIG. 2a.

At this time, the leaf spring 10 provided between the inner wall surface of the cylinder 1 and the movable body 6 biases the movable body 6 by its elastic force as shown in FIG. 2a or 2b. There is. The piston 1 applies a moving force that exceeds this biasing force, bends the leaf spring 10, and moves the movable body 6 toward the bottom side of the cylinder 2 or in the opposite direction. Therefore, the movable body 6 becomes stable in these two positions according to the movement of the piston 1, and hysteretic movement occurs here. When the movable body 6 is moved toward the bottom surface of the cylinder 2, the movable body 6 is pressed against the bottom surface of the cylinder 2 by the leaf spring 10. As a result, the packing body 7 effectively closes the exhaust port 4 and exhibits its valve action.

According to the adiabatic expansion engine configured with such a valve mechanism, the packing body 7 moves in the axial direction of the cylinder 2 without sliding on the inner wall of the cylinder 2, and receives the biasing force of the leaf spring 10. Thus, the exhaust port 4 is closed. Therefore,
There is no problem of wear caused by sliding of the packing body 7.
Moreover, since the movable body 6 does not slide on the inner circumferential surface of the cylinder 2, wear of the movable body 6 can be suppressed, and as a result, durability can be greatly improved. In addition, the leaf spring 10 has a function of selectively stabilizing the movable body 6 to two stable positions in the axial direction by a reversal action in the axial direction, so that when the intake valve 5 starts opening operation, The timing can be set so that the exhaust port 4 is rapidly and reliably closed in accordance with . Therefore, the dead space can be reduced and loss can be minimized, so that performance can be improved.

Note that the present invention is not limited to each of the embodiments described above. For example, the number of exhaust ports 4 provided on the bottom surface of the cylinder 2, the moving length of the moving body 6, etc. may be determined according to the specifications of the engine. Furthermore, the gas used for adiabatic expansion is not limited to the aforementioned He gas. In short, the present invention can be implemented with various modifications without departing from the gist thereof.

[Brief explanation of drawings]

Figures 1a and 1b are diagrams showing the configuration and movement of the main parts of a conventional adiabatic expansion engine, Figure 2a is a vertical cross-sectional view of the main parts of an expansion engine according to an embodiment of the present invention, and Figure 2b is the same. FIG. 3 is a cross-sectional view showing the end of the exhaust stroke of the engine. 1... Piston, 2... Cylinder, 3... Intake port, 4... Exhaust port, 6... Moving body, 7... Packing, 10... Leaf spring.

Claims (1)

[Claims] 1 A cylinder having an intake port and an exhaust port on the bottom surface, a piston provided in the cylinder so as to be able to reciprocate, the intake port is normally closed, and the piston is located at a first distance from the top dead center. an intake valve that is pressed by the piston to release the intake port and introduce high-pressure gas into the cylinder from the time when the intake valve approaches the cylinder until the time when the intake valve moves away from the cylinder via the top dead center to the first distance; The piston is movably provided in the cylinder, and the piston is provided in the first position relative to the top dead center.
Before it approaches the distance, it engages with the piston and moves to the bottom side of the cylinder, and
a moving body that engages with the piston before the piston reaches bottom dead center and moves in a direction away from the bottom surface side; and a moving body that supports the moving body without contacting the inner circumferential surface of the cylinder. and a spring member that selectively stabilizes the movable body in two stable positions in the axial direction by a reversal action in the axial direction; An adiabatic expansion engine comprising: a packing body that closes the exhaust port when the cylinder is in a stable position on the bottom side of the cylinder.