JPS6227273B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a multi-cylinder reciprocating compressor that is compact in structure, lightweight, and highly reliable, and more specifically, a single crosshead is provided with a plurality of pistons and cylinders to provide multiple necessary functions. The multi-cylinder reciprocating system is equipped with a compact and lightweight structure, and can perfectly balance the inertial force acting on the rotating parts of the crankshaft through balancing by combining a compression piston mechanism with a balance piston mechanism. This relates to a type compressor.

First, two problems to be solved by the present invention will be described in order based on FIGS. 1 to 3. First, regarding the first problem, FIG. 1 is a cross-sectional explanatory view showing a conventional example, and is a schematic cross-sectional view illustrating a reciprocating type non-lubricated compressor used for compressing gas. Reciprocating non-lubricated compressor (hereinafter simply referred to as compressor) K is a crank mechanism,
It consists of a piston mechanism that is connected to the crank mechanism and pressurizes gas. In the figure, the crank mechanism P consists of a crank case 1, a crankshaft O, a crank pin 5, a connecting rod 6, a crank bearing B, a crank pin bearing B', and a crosshead pin bearing C.
The piston mechanism Q consists of a crosshead 8, a crosshead guide 7, a piston rod 9, a piston 10 provided with a piston ring 2, and a cylinder 3. In the case of a non-lubricated compressor K, a distance piece 4 is provided between the cylinder 3 and the crankcase 1 so that the lubricating oil in the crankcase 1 flows into the cylinder 3 by the reciprocating movement of the piston rod 9. prevent,
An oil wiper ring 11 and a rod packing 12 are provided on both walls through which the piston rod 9 passes, in order from the crankcase 1 side. Usually, in order to drain oil sufficiently, the length of the distance piece 4, that is, the distance M between the oil wiper ring 11 and the rod packing 12, is configured to ensure the length of one stroke or more of the crank mechanism P. However, if it is necessary to remove oil more thoroughly, an oil removal ring 13 as shown in the figure is provided on the piston rod 9 to prevent lubricating oil from entering the cylinder 3 side. ing. Therefore, the compressor K that requires oil draining has a longer structure by the length (M) of the distance piece 4 compared to an oil-lubricated compressor that does not require oil draining, and therefore has a longer structure by the length (M) of the distance piece 4. It's also heavy. Also, extra space is required within the compressor due to the provision of the distance piece 4, but that space is not used to increase the compression function, and it must be said that it has become an uneconomical device. It won't happen. Similarly, even with conventional oil-lubricated compressors that do not use distance pieces, the space cannot be said to be fully utilized. Particularly in recent years, when we consider the case where it is used in combination with cutting-edge technology such as ultra-high speed or cryogenic technology, it goes without saying that it is functionally superior, but it also has a compact structure and is lightweight. Compressors are becoming an essential requirement.

Next, we will discuss the second issue. Figure 2 is an explanatory diagram of the reciprocating mechanism of the piston, with the crank radius r,
Connecting rod length l, connecting rod ratio r/l=λ, top dead center X
Assuming that the crank angle θ measured from , the angle β between the connecting rod and the cylinder axis, the displacement x of the piston from the top dead center
The acceleration α of the piston is usually expressed by the following equation.
That is, α=rω ² (cos θ + λ cos 2 θ) ... (1) The inertial force F that acts on the piston, piston rod, crosshead, connecting rod, crank pin, etc. due to the above acceleration is, assuming that the reciprocating weight of these is W, F = -W /gα=-W/grω ² (cosθ+λcos2θ
) =-W/grω ² cosθ-λ/4 W/gr(2ω) ²
cos2θ ... is given by (2).

When one end on the crosshead side reciprocates like a connecting rod and the other end on the crankpin side rotates, a reciprocating inertia force F ₁ and a centrifugal force F _B due to centrifugal acceleration are generated. The force of the compressed gas acting on the surface of the piston is a force of action and reaction inside the machine, and does not become a force to the outside through the foundation of the compressor, but it is caused by the reciprocating inertia force F ₁ , centrifugal force F _B and these forces. The moment caused by the force acts as an external force. As a means to minimize these external forces and reduce the occurrence of vibrations, for example, in the case of a normal one-cylinder compressor, a balance weight is attached to the opposite side of the crank arm. However, if the balance weight is attached only to balance the entire rotating part including the rotating weight at the tip of the connecting rod,
Since the entire reciprocating inertia force F ₁ remains, the balance weight is normally made larger than this to balance 50% of the reciprocating inertia force F ₁ with the centrifugal force (half balance). Figure 3 shows these force relationships. As shown in the figure, if the balance weight is set to half balance (W/2), the crank angle θ is at an arbitrary position, and the inertia force F ₁ in the direction of the reciprocating movement of the piston as shown by the white arrow [F ₁ = W/grω ² cos θ] (hereinafter referred to as primary inertia force) and the centrifugal force F _B of the balance weight [F _B = 1/2 W/grω ² ], resulting in a resultant force F _N
is distributed as shown in the figure on the left, and the excitation force in the vertical and horizontal directions is approximately half amplitude [1/2 W/gr
ω ² ]. That is, when viewed in the reciprocating direction of the piston, the primary inertial force F ₁ is halved, but when viewed in the right angle direction, an additional inertial force of 1/2 W/grω ² is generated. In other words, this is just a portion of the primary inertial force F ₁ that is changed in the vertical direction by the half balance. Also, if the inertial force of the second term in the above equation (2) (hereinafter referred to as secondary inertial force) is F ₂ , then as can be understood from the equation F ₂ = -λ/4 W/gr(2ω) ² cos2θ 2 in the secondary inertia force F ₂
Since it includes the angular velocity term of ω, the crankshaft's 2
It is impossible to balance the inertial force F ₂ with twice the angular velocity using only a balance weight. In this way, although it is possible to reduce the primary inertia force with the half balance using the current balance weight, a new inertia force (1/2F ₁ ) equal to the amount of reduction is generated in the vertical direction, and an additional secondary inertia force (F 1 ) is generated in the vertical direction. ₂ ) is not acting at all on the unbalance, so the balance against inertial force has not been completely resolved, which causes vibrations in the compressor, and the need for higher rotation speeds and even shorter strokes. This is preventing people from becoming more popular.

The present invention has been made in view of the above-mentioned circumstances, and it aims to make the internal structure of a reciprocating compressor more compact and lightweight while ensuring necessary functions, and to create a balance piston mechanism in combination with a compression piston mechanism. The present invention aims to provide a multi-cylinder reciprocating compressor that can completely balance the inertial forces acting on the rotating parts of the crankshaft, etc.

That is, the structure of the present invention that achieves the above object is as follows:
A reciprocating compressor is provided with a crosshead that reciprocates in a direction perpendicular to the crank axis O through a crank mechanism with a radius r and a connecting rod with a length l, and a compression piston is attached to the crosshead. On the mechanism P side, in a plane perpendicular to the center line L connecting the crankshaft center point and the crosshead center point, and at the center point C of the crosshead.
A plurality of piston rods are provided protruding parallel to the sliding direction of the crosshead at a position where the crosshead is removed, and pistons and cylinders are provided at the tip of each piston rod to constitute a plurality of compression piston mechanisms. A pair of balance piston mechanisms are provided at positions parallel to the crankshaft O and at equal distances a and a in opposite directions from the center of gravity Z of the entire compression piston mechanism existing in the center of gravity, and the balance piston mechanism and the crank mechanism are connected by a connecting rod mounted at a position 180° out of phase with the connecting rod mounting position of the crank mechanism, and the weight of the balance piston mechanism is equal to the total reciprocating weight of the compression piston mechanism. The crank radius of the balance piston mechanism is the same length as the crank radius r of the compression piston mechanism, and the connecting rod and the connecting rod are formed to have the same length l. It is something to do.

The configuration and effects of the present invention will be explained below in detail based on the drawings showing the embodiments. However, the embodiments below are only one specific example, and the design may be modified in various ways in keeping with the spirit described above and below. All are included within the technical scope of the present invention.

FIG. 4 is a schematic cross-sectional view illustrating the multi-cylinder compressor of the present invention, FIG. 5 is a cross-sectional view taken along the line - in FIG. 4, and FIG. 6 is a view seen from the direction of the arrow in FIG.
FIG. 7 is a sectional view taken along the line -- in FIG. 5, and FIG. 8 is an explanatory diagram of the operation. Illustrated vertical compressor Ka
is the center point of the crankshaft center O and the crosshead 8
A plurality of piston rods 9a, 9a are provided protruding toward the crank mechanism P side in a plane orthogonal to the center line L (dotted chain line) connecting the center points of the crosshead 8, and at positions Ta, Ta that are off the center point of the crosshead 8. At the same time, compression pistons 10a, 10a and a cylinder 3 are provided with piston rings 2a at the tips of the piston rods 9a, 9a, respectively.
a, 3a are provided to constitute a multi-cylinder compressor. That is, the crosshead 8 and the cylinders 3a, 3a are disposed on opposite sides of the crank mechanism P.
Distance pieces 4a, 4a having an oil wiper ring 11a and a rod packing 12a at both ends and maintaining a required distance M between them are provided in the crankcase 1a. On the other hand, center line L
In the above, the balance piston 1 is located at an equal distance interval a, a from the center of gravity position Z of the entire weight of the compression piston mechanism in parallel to the crankshaft center O and in opposite directions.
4a, 14a are provided in the same direction as the compression pistons 10a, 10a. The balance piston 14a and the crank mechanism P are connected to the connecting rod 17a via a crank pin 16a, a crank pin bearing B', and a balance piston pin bearing H, which are provided at a position 180 degrees out of phase with the mounting position of the connecting rod 6. They are connected together. It is assumed that the length l' of the connecting rod 17a is the same as the length l of the connecting rod 6, and that the crank radius of the connecting rod 17a is the same as that of the connecting rod 6 and has a rotation radius r.

FIG. 6 shows balance pistons 14a, 14a arranged between cylinders 3a, 3a. That is, the crosshead 8 and the compression piston 10a are made of a material with low specific gravity, such as a light alloy such as an aluminum alloy or a magnesium alloy, and the balance piston 14a is made of a material with a high specific gravity such as iron. By increasing the ratio of diameter), the crankcase 1a can be made thinner, and by doing so, the main bearing span can be reduced, so the crankshaft can be made thinner.

On the other hand, the balance piston guide 15a provided along the balance piston 14a has a double tube structure, that is, the balance piston guide 15a shown in FIG. 7 has the balance piston 1 in the center.
4a, and balance piston 1 is inserted outside of it.
A gas passage 18a is formed at the head of the gas passage 4a. In addition, when providing the balance pistons 14a, 14a, the reciprocating weight of each balance piston (the total weight of the weight of the balance pistons 14a, 14a and the reciprocating weight of the connecting rod 17a) is equal to the total reciprocating weight of the reciprocating body (a general term for the members described below). It is constructed so that the relationship is 1/2 of the weight W (the total weight of the crosshead 8, piston rods 9a, 9a, compression pistons 10a, 10a, and the reciprocating weight of the connecting rod 6). Compressor Ka has the same structure as compressor K, including crankshaft O, crank pin 5, connecting rod 6, crank bearing B, crank pin bearing B', and crosshead pin bearing of crank mechanism P, but with regard to piston mechanism Q. The crosshead 8 and crosshead guide 7 are each single, but the piston rod 9
a, a plurality of pistons 10a and a plurality of cylinders 3a, and a piston mechanism Q is connected to a crosshead 8.
It is completely different from conventional compressors in that it is provided on the side of the crank mechanism P, and distance pieces 4a, 4 are installed using the space formed inside the crankcase 1a.
Since a is provided, not only the surplus space of the crank mechanism P is utilized, but also the crankcase 1a is shortened, which contributes to the weight reduction of the entire crankcase. Coupled with the effect of cylinderization, its utility value has greatly improved. Furthermore, if the distance pieces 4a, 4a are not provided, it can be used as an oil-lubricated compressor as is.

Next, the inertia force of the balance pistons 14a, 14a with a reciprocating weight W/2, which are provided 180 degrees out of phase with the inertia force F expressed by the above equation (2) generated by the total reciprocating weight W of the reciprocating bodies. Fc is Therefore, two balance pistons 14a, 14a
The ^total inertial force generated by
2Fc cancel each other out. FIG. 8 is a diagram schematically showing the situation.

Regarding the inertial couple, there are balance pistons 14a, 14 on both sides at equal distances a, a from the center of gravity Z of the reciprocating body.
Since the balance pistons 14a and 14a have the same direction of force, they cancel each other out and no force couples are generated.

Next, FIG. 9 is a diagram showing another example of FIG. 7, in which the balance piston 14c is connected to the balance piston guide 1.
5c, and the gas passage 18c is provided to one side.

FIG. 10 is a diagram showing a modification of FIG. 6, and illustrates the arrangement of the cylinder 3d and balance piston 14d when the compression piston mechanism has four cylinders.
The balance pistons 14d, 14d are provided in the middle part between the two cylinders 3d, 3d, and are connected to the gas passage 18.
d is provided between the balance pistons 14d, 14d. If arranged like this, there will be 2 compression cylinders.
It is not limited to books, but can be any number of books.

Since the present invention is configured as described above, the following effects can be obtained. That is, the counter piston system allows for a significant shortening in the stroke direction, and even with the provision of a balance piston, a lightweight multi-cylinder compressor with a compact structure can be obtained.

It is possible to completely eliminate the residual unbalance of the inertial force acting on the rotating parts of the crankshaft, and it is also possible to increase the rotation speed and shorten the stroke.

Although it is provided with one crosshead, it can be applied to multi-stage compression, and a multi-stage cylinder type compressor can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a schematic cross-sectional view showing a conventional example, Figs. 2 and 3 are explanatory views of the same, Fig. 4 is a schematic cross-sectional view illustrating the present invention, and Fig. 5 is a cross-sectional view taken along the line - in Fig. 4. figure,
6 is a cross-sectional view taken along the line arrow in FIG. 5, FIG. 7 is a cross-sectional view taken along the line -- in FIG. Schematic diagram, 1st
FIG. 0 is an explanatory diagram showing another embodiment. 1... Crank case, 2... Piston ring, 3... Cylinder, 4... Distance piece, 5... Crank pin, 6... Connecting rod, 7...
Crosshead guide, 8...Crosshead, 9...
...Piston rod, 10...Compression piston, 11...
Oil wiper ring, 12...Rod packing, 13...Oil drain ring, 14...Balance piston, 15...Balance piston guide, 1
6...Crank pin, 17...Joining rod, 18...
Gas passage, P...crank mechanism, Q...piston mechanism.

Claims (1)

[Claims] 1. In a reciprocating compressor that is provided with a crosshead that reciprocates in a direction perpendicular to the crank axis via a crank mechanism with radius r and a connecting rod with length l, and a compression piston is attached to the crosshead, the crank of the crosshead A plurality of piston rods are provided on the mechanism side, in a plane orthogonal to a center line connecting the crankshaft center point and the crosshead center point, and at positions away from the center point of the crosshead, protruding parallel to the sliding direction of the crosshead. A plurality of compression piston mechanisms are constructed by providing a piston and a cylinder at the tip of each piston rod, and the direction is parallel to and opposite to the crankshaft center from the center of gravity of the entire compression piston mechanism existing on the center line. A pair of balance piston mechanisms are provided at positions equidistant apart from each other, and the balance piston mechanisms and the crank mechanism are located 180 degrees apart from the connecting rod mounting position of the crank mechanism.
° The reciprocating weight of the balance piston mechanism is equal to half the total reciprocating weight of the compression piston mechanism, and the crank of the balance piston mechanism A multi-cylinder reciprocating compressor characterized in that the radius is the same length as the crank radius r of the compression piston mechanism, and the connecting rod and the connecting rod are formed to have the same length l.