JPH11343802A - Reciprocating piston fluid machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the full height of a fluid machine by reducing a closest distance between the boss outer wall surface of a piston pin hole and the outer wall surface of a crankshaft and forming a notch in a cylinder for preventing interference with the large end part of a connecting rod. SOLUTION: A closest distance between the boss outer wall surface of a piston pin hole and the outer wall surface of a crankshaft is set equal to 0.4 times or smaller than a cylinder inner diameter, and a notch 10 having a width equal to 0.5 times or smaller than the cylinder inner diameter is formed in a cylinder 1 for preventing interference with the large end part of a connecting rod 6. Regarding a counter weight for reducing an imbalanced inertial force generated by the motion of a piston-crank mechanism, no counter weights are provided for simplifying a low-rotational type structure in a first case and, in a second case, counter weights 14 and 14' are provided in a crank chamber 2. In a third case, one counter weight is provided in the crank chamber 2, and the other counter weight is provided outside the crank chamber 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reciprocating piston type fluid machine used as an air compressor or a hydraulic pump.
It is related to the one in which the closest distance between the outer wall surface of the boss portion of the hole for the piston pin and the outer wall surface of the crankshaft is made much smaller than before so as to reduce the overall height.

[0002]

2. Description of the Related Art In order to reduce the size of a reciprocating piston type fluid machine generally used as an air compressor or a hydraulic pump, it is desired to reduce the center-to-center distance between a piston pin and a crankshaft. There were problems such as interference between the large end of the connecting rod and the cylinder, and interference between the piston and the counterweight, and there was a limit to miniaturization.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to reduce the closest approach distance between the outer wall surface of the boss portion of the piston pin hole and the outer wall surface of the crankshaft and prevent interference with the large end of the connecting rod. The notch is formed in the cylinder to reduce the overall height of the reciprocating piston type fluid machine.

[0004]

Means for Solving the Problems In order to solve the conventional drawbacks, the first aspect of the present invention is to determine the closest distance between the outer wall surface of the boss portion of the hole for the piston pin and the outer wall surface of the crankshaft as 0.
When a notch having a width of not more than 4 times and having a width of not more than 0.5 times the inner diameter of the cylinder for preventing interference with the large end of the connecting rod is formed in the cylinder and the piston skirt portion passes through the notch. However, it was configured so that it could contact the inner wall surface of the cylinder with a large area. According to a second aspect of the present invention, in addition to the structure of the first aspect, a counterweight for reducing unbalanced inertial force caused by the movement of the piston-crank mechanism is provided at a position inside the crankshaft inside the crankcase and at a position which does not interfere with the piston. I prepared it. According to a third aspect of the present invention, in addition to the structure of the first aspect, one of the counterweights is provided on the crankshaft inside the crankcase and at a position not interfering with the piston, and the other counterweight is changed in position to change the position of the crankcase. An external crankshaft is provided.

[0005]

FIG. 1 shows an embodiment of a reciprocating piston type fluid machine according to the present invention, which comprises a connecting rod 6 for connecting a crankpin 7 and a piston pin 4 at a position eccentric from the axis of a crankshaft 9. Cylinder 1 by lowering stroke of piston 3
The fluid (gas or liquid) sucked in via a suction valve 11 (reed valve type in the figure) is compressed by an ascending stroke and then discharged through a discharge valve 12 (reed valve type in the figure). . In this structure, it is divided along the line AA 'and each is firmly fastened by bolts. In the present invention, FIG.
As shown in (d), the closest approach distance 1 (distance at the bottom dead center) between the outer wall surface of the boss portion 5 of the piston pin hole and the outer wall surface of the crankshaft is made extremely small to pursue miniaturization. That is, generally, assuming that the cylinder inner diameter is D, the piston skirt height L = 0.46 × (1.15 + 0.08) · D ≒
0.57 · D, boss outer diameter of hole for piston pin = 0.4
4D (internal combustion engine Vol16, No1
93, extra edition, p78, or compressor design,
Power Co., p. 47, however, the latter is shown as a very rough value, so the former was referred to within a range that does not contradict each other). Therefore, if the margin S for preventing interference between the end of the piston skirt and the outer wall surface of the crankshaft is 2 mm in the class of D = 30 to 100 mm, S = (0.02 to 0.067) ·
Since D, l = L−0.44 · D / 2 + S ≒
0.4 · D. The present invention is characterized in that the value of l is set to 0.4.D or less in the sense of a general limit within a range where there is no interference between the end of the piston skirt and the outer wall surface of the crankshaft. FIG. 1 (a) pursues the present invention to the utmost extent, in which a notch 13 is formed at the end of the skirt of the piston 3 to allow the crankshaft 9 to bite (notch 13).
Therefore, the closest distance l between the outer wall surface of the boss of the piston pin hole and the outer wall surface of the crankshaft is extremely small (for example, 2 mm). Further, a notch 10 for preventing interference with the large end of the connecting rod 6 is formed in the cylinder 1. Both ends of the large end of the connecting rod 6 are shown in FIG. The surface is 2 m each in the notch 10
If the width W of the notch 10 is excessively large, the contact area between the piston skirt portion and the cylinder becomes small, and there is a possibility that vibration and noise may occur. In view of such circumstances, in the present invention, the width W of the notch 10 is set to 0.5 times or less of the inner diameter of the cylinder (more preferably, 0.4 times or less). The crank arm 8 is shaped so as not to interfere with the piston skirt end of the cylinder 1 and the part to be slid. (If it is configured to allow the interference between the two, the piston skirt and the cylinder inner wall surface are located at the bottom dead center. The area of contact with the wire is reduced, causing vibration and hammering.) Reciprocating piston type fluid machines used as air compressors or hydraulic pumps are generally low-rotation types, and often do not have counterweights to reduce the unbalanced inertial force generated by the movement of the piston-crank mechanism. Although not provided in FIG. 1A, the counterweights 14 and 14 'are provided on the crankshaft inside the crank chamber 2 and at positions not interfering with the piston 3 as shown in FIG. Since the balance is improved and high-speed rotation is possible, the size is further reduced (the space for accommodating the counterweights 14 and 14 'communicates with the crankcase 2, so this space is also considered to be a part of the crankcase). ).
In this case, one end of the crankshaft 9 (the right end in the figure)
Counterweight 1
The drive pulley 4 may be provided (built in the drive pulley). That is, one of the counterweights is provided on the crankshaft outside the crankcase 2, and the other is provided on the crankshaft inside the crankcase 2 and at a position not interfering with the piston 3. As for the method of supporting the crankshaft, it is also conceivable to use a cantilever as shown in FIG. 1 (c) (a cross section taken along the line BB 'is shown in FIG. 2 (b)). Because there is no crank arm, it is very easy, and it is not necessary to divide the large end into two parts, and it can be an integral type. In FIG. 1 (a), the connecting rod 6 is divided into two at its large end in terms of assembly to the crankpin 7, and each is firmly fastened by bolts. 1
Reference numeral 4 denotes a counterweight provided in the crank chamber 2 (which can be omitted when used at a low rotation), since generation of a couple moment due to the distance h is inevitable.
Another counterweight as shown in FIG. 3 (c) to the crank chamber 2 of the outer crankshaft on may be provided (which is the f ₂ inertial force generated). f ₁ is the piston - omitted inertia crank mechanism occurs, f ₃ in the inertial force counterweights 14 occurs, since either balancing these inertial force what kind is known. In the present invention, since the ratio between the connecting rod length (center distance between the large end and the small end) and the crank radius is small, it is necessary to reduce the reciprocating inertial mass to suppress the secondary vibration, Light alloy connecting rods are preferred. Next, in FIG. 2A, if there is any reason, a structure in which the portion of the crank arm 8 near the crankpin is fitted into the notch 10 according to the rotation as shown in FIG. The part is used for positioning). In addition, in FIG. 2A, while keeping the shortest distance r from the center of the crankshaft to the outer peripheral surface of the crankpin constant, as shown in FIG. If the crankshaft is configured to rotate about the shaft (increase the diameter of the crankpin), the center-to-center distance between the crankpin 7 and the crankshaft 9 increases, so that the crank radius becomes large and the size is reduced if the displacement is the same. I can do things.
The above also applies to FIG. In the present invention, FIG.
If the notch 15 for preventing interference with the crankshaft is formed in the boss portion 5 of the piston pin hole as shown in FIG. Because it can be shortened, miniaturization will progress further. FIG.
(B) is a diagram in which the axis of the crankshaft 9 is eccentric from the axis of the cylinder to the thrust side (schematically shown). it can. This is particularly effective when the length of the connecting rod is short as in the present invention. The present invention is also applicable to a multi-cylinder reciprocating piston type fluid machine, and may be of a series type, a V type, or a horizontally opposed type. FIG. 3 (D) schematically shows the case of a V type / two cylinder type. . Although the counterweight is not provided in the figure, it may be provided to improve the dynamic balance and achieve high-speed rotation (this makes the dynamic balance very good in combination with the V-type).

[0006]

According to the present invention, the closest distance 1 between the outer wall surface of the boss portion of the piston pin hole and the outer wall surface of the crankshaft is set to 0.4 times or less the inner diameter of the cylinder. Conventionally, with such a configuration, the large end of the connecting rod interferes with the cylinder, and the configuration of the present invention was considered impossible. That is, since the large end of the connecting rod interferes with the cylinder, it is not possible to consider from the beginning to reduce the closest approach distance l to a certain value or more, and it is hard to think of any means to form the notch 10. In other words, it can be said that this configuration of the present invention was in the blind spot from the beginning. On the other hand, in the present invention, a drastic idea was made, and the notch 10 for preventing the interference with the large end of the connecting rod 6 was formed in the cylinder so that the closest approach distance l was made smaller than previously thought. In this case, if the interference between the two is to be prevented by a simple idea that does not form the notch 10, the crank radius must be made very small, which is not practical. That is, the notch 10 plays an important role in increasing the crank radius. In addition, since the width of the notch 10 is designed to be 0.5 times or less of the inner diameter of the cylinder, the piston skirt portion comes into wide contact with the cylinder, and the generation of vibration and noise is reduced. In addition, when high-speed rotation with good dynamic balance with a counterweight,
Since the counterweights 14 and 14 'are provided at positions where they do not interfere with the piston 3, the closest approach distance l can be made smaller than previously thought. FIG.
(A) has a piston inner diameter of 40 mm, a crank radius of 24 mm, and a displacement of 30 cc. The piston inside diameter is 4 mm larger than the conventional one with the same displacement,
The total height of the fluid machine decreases by about 34 mm. As described above, according to the present invention, the overall height of the reciprocating piston type fluid machine is significantly reduced, and the size and weight of the machine are significantly reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of a reciprocating piston type fluid machine according to the present invention.

FIG. 2 is a sectional view taken along line AA ′ or BB ′ in FIG. 1;

FIG. 3 is a schematic view of various embodiments of a reciprocating piston type fluid machine according to the present invention.

[Explanation of symbols]

1 is a cylinder, 2 is a crank chamber, 3 is a piston, 4 is a piston pin, 5 is a boss of a hole for a piston pin, 6 is a connecting rod, 7 is a crankpin, 8 is a crank arm, 9 is a crankshaft, and 10 is a crankshaft. Notch, 11 is a suction valve, 12 is a discharge valve, 13 is a notch, 14 and 14 'are counterweights, and 15 is a notch.

Claims (7)

[Claims] 1. A connecting rod for connecting a crankpin and a piston pin which is eccentric from an axis of a crankshaft, wherein a suction valve is opened in a cylinder to compress absorbed fluid, and then discharged through a discharge valve. In a reciprocating piston type fluid machine, the closest distance between the outer wall surface of the boss portion of the hole for the piston pin and the outer wall surface of the crankshaft is defined as 0.
A notch having a width of not more than 4 times and having a width of not more than 0.5 times the inner diameter of the cylinder for preventing interference with the large end of the connecting rod is formed in the cylinder, and the piston skirt portion passes through the notch. In order to reduce the unbalanced inertial force generated by the movement of the piston-crank mechanism, the crankshaft inside the crankshaft must be installed. And a reciprocating piston type fluid machine characterized by being provided at a position where it does not interfere with the piston. 2. The reciprocating piston type fluid machine according to claim 1, wherein a counterweight for reducing unbalanced inertial force generated by movement of the piston-crank mechanism is removed from the beginning. 3. The reciprocating piston type fluid machine according to claim 1, further comprising a counterweight for reducing an unbalanced inertial force generated by the movement of the piston-crank mechanism. A reciprocating piston type fluid machine, wherein the reciprocating piston type fluid machine is provided on the crankshaft and at a position not interfering with the piston, and the other counterweight is repositioned to be provided on the crankshaft outside the crankcase. 4. The reciprocating piston type fluid machine according to claim 1, wherein a notch is formed at an end of the skirt of the piston to allow the crankshaft to bite. 5. The reciprocating piston type fluid machine according to claim 4, wherein a notch is formed in the boss portion of the piston pin hole to prevent interference with the crankshaft. 6. The crank radius is increased by configuring a part of a crank pin to rotate around a crank shaft beyond a part corresponding to an inner peripheral surface of a cylinder.
A reciprocating piston fluid machine according to any one of the above. 7. The reciprocating piston type fluid machine according to claim 1, wherein the axis of the crankshaft is eccentric from the axis of the cylinder toward the thrust side.