JP2000045973A - Oil injection type screw compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oil injection type screw compressor with simplified construction, reducing the work needed for manufacture and maintenance. SOLUTION: An oil injection type screw compressor 1 is provided with a capacity adjusting slide valve 16 which operates in connection to a piston rod 18 of a hydraulic cylinder 2 located on the discharge side. The hydraulic cylinder 2 is made compressible with pressure oil only in the direction from the discharge side to the intake side, as a single acting cylinder. At the same time, the compressor is also provided with a spring 3 for urging the slide valve 16 from the intake side to the discharge side at all times.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil-cooled screw compressor having a slide valve for adjusting a capacity.

[0002]

2. Description of the Related Art Conventionally, an oil-cooled screw compressor equipped with a capacity-adjusting slide valve is well known, and FIG. 17
No. 3872). The screw compressor 11 includes a screw rotor 15 rotatably housed in a rotor chamber of a casing 14 having an inlet 12 on one side and an outlet 13 on the other side, and a screw rotor 15 and a casing. And a displacement adjusting slide valve 16 movably provided along the axial direction of the screw rotor 15 between the screw rotor 15 and the screw rotor 15. The slide valve 16 is a hydraulic cylinder 1 located on the discharge side.
7 is connected to the piston rod 18. In addition, a stopper 19 that defines the rightward movement limit of the slide valve 16 in FIG. 6 is provided above the end of the screw rotor 15 on the suction side.
Is provided.

[0003] The space in the hydraulic cylinder 17 is closed by an annular rod cover 21 having a piston rod 18 penetrated through a seal member 20, and a seal member 2 is provided on the outer peripheral portion.
2 is divided into a first chamber 24 on the rod cover 21 side and a second chamber 25 on the opposite side of the rod cover 21, which is partitioned by the piston 23 to which the rod 2 is attached. At the end of the first chamber 24 on the side of the rod cover 21, there is provided a conduit 31 for communicating the first chamber 24 with the discharge port 13, and the end of the second chamber 25 opposite to the rod cover 21. Is connected to a conduit 32 for leading high-pressure oil. A spring 26 is provided around the piston rod 18 between the piston 23 and the rod cover 21.
Is provided so that the piston 23 is constantly biased toward the second chamber 25 side.

[0004] Further, together with a pipe 33 branching off from the pipe 32 and leading to the low-pressure section, two pipes 34 for communicating the space in the hydraulic cylinder 17 with the low-pressure section at different positions in the axial direction of the hydraulic cylinder 17. , 35 are provided, and on-off valves 36, 3 are provided in each of the pipelines 33, 34, 35.
7, 38 are interposed. And, the on-off valves 36, 37,
The position of the piston 23 is controlled by opening one of the 38. Therefore, the slide valve 16 corresponds to the position of the piston 23.
Is also controlled, and the capacity of the screw compressor 11 is adjusted.

[0005]

In the case of the conventional apparatus described above, high-pressure gas is introduced into the first chamber 24 of the piston 23 on the slide valve 16 side, and the resulting pressure is applied to the piston 23 together with the force of the spring 26. It has become. Therefore, in order to make the first chamber 24 a closed space, the rod cover 21 to which the seal member 20 is attached becomes necessary.
It is also necessary to provide a conduit 31 for guiding the high-pressure gas to the first chamber 24. For this reason, the structure of the screw compressor 11 becomes complicated, and there is a problem that the labor required for manufacturing and maintenance increases accordingly, leading to an increase in cost. SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and has been made to provide an oil-cooled screw compressor that has a simplified structure and can reduce labor required for manufacturing and maintenance. Is what you do.

[0006]

In order to solve the above-mentioned problems, a first aspect of the present invention is to provide an oil-cooled screw having a capacity-adjusting slide valve which is operated by being connected to a piston rod of a hydraulic cylinder located on a discharge side. In the compressor, the hydraulic cylinder is a single-acting cylinder type, and the piston can be pressurized only from the discharge side to the suction side by pressure oil. In this configuration, an elastic member biasing toward is provided.

According to a second aspect of the present invention, in addition to the configuration of the first aspect, a plurality of conduits for guiding hydraulic oil in the hydraulic cylinder to a low-pressure portion from different positions in the axial direction of the hydraulic cylinder, and An on-off valve interposed was provided for each.

[0008]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an oil-cooled screw compressor 1 according to a first embodiment of the present invention, and portions common to FIG. 6 are assigned the same reference numerals and description thereof is omitted. The screw compressor 1 uses a single-acting cylinder type hydraulic cylinder 2 positioned on the discharge side, and a spring 3 as an elastic member that constantly urges the slide valve 16 from the suction side to the discharge side. The end of the hydraulic cylinder 2 opposite to the slide valve 16 is connected to a pipe 5 communicating with the space 4 in the hydraulic cylinder 2. The pipe 5 is used to supply high-pressure oil. It is connected to a pipe 5A and a pipe 5B communicating with the low-pressure section. Further, an opening / closing valve 6A and a restricting means 7, for example, a capillary tube, are provided in the pipe 5A.
Is provided with an on-off valve 6B.

Then, by closing the on-off valve 6B and opening the on-off valve 6A, high-pressure oil is introduced into the space 4 through the pipelines 5A and 5 so that the piston 23 has a discharge-side surface. When the piston 23 advances to a desired position by overcoming the acting discharge pressure and the force of the spring 3, the on-off valve 6A
Is closed, the slide valve 16 is also advanced to a desired position, and the capacity of the screw compressor 1 can be increased to a desired value.

Conversely, by closing the on-off valve 6A and opening the on-off valve 6B, the space 4 is reduced by the discharge pressure acting on the surface of the piston 23 on the discharge port 13 side and the force of the spring 3. The oil in the space portion 4 pressurized by the piston 23 moving as described above is guided to the low-pressure portion via the pipelines 5 and 5B, and when the piston 23 is retracted to a desired position,
By closing the on-off valve 5B, the slide valve 16 is also retracted to a desired position, and the capacity of the screw compressor 1 can be reduced to a desired value. In this way, the capacity of the screw compressor 1 is continuously adjusted.

By the way, the throttle means 7 provided in the pipe 5A
May be provided on either the primary side or the secondary side of the on-off valve 6A, and serves to prevent oil from flowing into the space portion 4 abruptly and keep the forward speed of the slide valve 16 properly. I have. FIG. 1 shows a state in which the slide valve 16 has moved to the movement limit on the suction side and has reached a capacity of 100% in contact with the stopper 19.

FIGS. 2 to 5 show an oil-cooled screw compressor 1A according to a second embodiment of the present invention. Portions common to those in FIG.
In this screw compressor 1A, the same pipelines 5, 5
In addition to A, 5B and the on-off valves 6A, 6B, a plurality of, in the illustrated example, two conduits 5C, 5D for guiding the hydraulic oil in the hydraulic cylinder 2 from different positions in the axial direction of the hydraulic cylinder 2 to the low-pressure portion. It is provided. On-off valves 6C, 6D are also provided in the pipes 5C, 5D, respectively. 2-5, the on / off valves 6A-6D in black represent closed states, while the open / closed valves 6A-6D represent open states. An arrow indicated by a dashed line indicates a flow state in which the gas once sucked by the screw rotor 15 returns to the suction port 12 through an opening formed between the stopper 19 and the slide valve 16.

For example, when the screw compressor 1A is to be in a state of 25% capacity, as shown in FIG.
A, 6C and 6D are closed, and the on-off valve 6B is opened. As a result, the piston 23 moves to the position of the opening of the pipe 5 on the space portion 4 side, that is, the slide valve 16 moves to the retreat limit together with the piston 23, and is kept in that state. When the screw compressor 1A is set to the state of 50% capacity, FIG.
The on-off valves 6B and 6D are closed as shown in FIG.
A and 6B are opened. As a result, the piston 23 moves to the position of the opening of the pipe 5C on the space portion 4 side, and the slide valve 16 moves together with the piston 23, and the state is maintained.

When the capacity of the screw compressor 1A is 75%, as shown in FIG. 4, the on-off valves 6B and 6C are closed and the on-off valves 6A and 6D are opened. As a result,
The piston 23 moves to the position of the opening on the space portion 4 side of the conduit 5D, and the slide valve 16 moves together with the piston 23, and is kept in that state. In the case shown in FIGS. 2 and 3, high-pressure oil is supplied to the space 4 while the pipe 6
It continues to flow out to C or 6D, and the balance of the forces acting on both sides of the piston 23 is maintained. When the screw compressor 1A is set to the state of 100% capacity, the open / close valves 6B, 6C and 6D are closed and the open / close valve 6A is opened as shown in FIG. As a result, the slide valve 16 moves to the position of the forward limit together with the piston 23, and the slide valve 16 and the stopper 19 come into contact with each other and are kept in that state. In this case, no opening is formed between the slide valve 16 and the stopper 19, and the gas suction port 1 for the gas once sucked.
There is no return gas to 2.

Thus, the capacity of the screw compressor 1A is adjusted stepwise. When performing the stepwise adjustment of the capacity in the screw compressor 1A, FIGS.
In the state shown in FIG. 5, the pressure of the high-pressure oil is acting on the space 4, and when the capacity is to be reduced, the pressure in the space 4 is reduced to reduce the piston 23. Need to be retracted. For this reason, the pipes 5B, 5C, 5D are less than the oil amount supplied from the pipe 5A.
It is necessary to make the amount of oil released from any one of the above to the low-pressure portion larger, and the throttle means 7 performs such an operation. That is, the amount of oil supplied from the pipe line 5A is limited by the throttle means 7. Also in this screw compressor 1A, the throttle means 7 is provided on the primary side of the on-off valve 6A,
It may be provided on any of the secondary sides.

The present invention is not limited to the one provided with the on-off valve 6A, but also includes an oil-cooled screw compressor without the on-off valve 6A. When the on-off valve 6A is not provided, the oil from the pipe 5A continues to flow into the pipe 5B even in the state shown in FIG. 2, and the piston 23 is maintained in the state shown in the figure. Further, the high-pressure oil in the pipe line 5A may be supplied from an oil reservoir at the lower part of an oil separator / collector provided in a discharge passage (not shown) of the screw compressors 1 and 1A, for example. In addition, pipelines 5B and 5
The low-pressure portion through which C and 5D communicate may be a portion that communicates with the suction port 12 of the screw compressors 1 and 1A.

Further, continuous control and stepwise control of the capacity have been described as separate screw compressors.
If the on-off valves 6C and 6D of the screw compressor 1A shown in FIGS. 1 to 5 are kept closed, the screw compressor becomes substantially the same as the screw compressor shown in FIG. 1, and the screw compressor 1A shown in FIGS. Can also be used for the two types of control described above. By the way, the space in the hydraulic cylinder for operating the slide valve 16 is narrow, and it is impossible to provide a spring that generates a large spring force in this space. However, in the present invention, such a space is limited. Since the spring 3 is provided on the suction side of the slide valve 16, the specifications of the spring 3 can be determined so as to generate a large spring force.

[0018]

As is apparent from the above description, according to the first aspect of the present invention, the oil-cooled screw compression provided with the capacity-adjusting slide valve operatively connected to the piston rod of the hydraulic cylinder located on the discharge side. The hydraulic cylinder is a single-acting cylinder type, and the piston can be pressurized only by pressure oil from the discharge side to the suction side, and in addition to this hydraulic cylinder, the slide valve is always moved from the suction side to the discharge side. The configuration is such that an elastic member that urges toward it is provided. For this reason, the discharge port side of the piston of the hydraulic cylinder does not require any processing for forming a closed space, and therefore, a pipe connecting this closed space to the discharge port is not required, and the structure is simplified, This has the effect of reducing the labor required for maintenance.

According to a second aspect of the present invention, in addition to the configuration of the first aspect, a plurality of conduits for guiding hydraulic oil in the hydraulic cylinder to a low-pressure portion from different positions in the axial direction of the hydraulic cylinder, and An on-off valve is provided for each of them. For this reason, in addition to the effect of the first invention, there is an effect that the capacity of the screw compressor can be adjusted stepwise as well as continuously.

[Brief description of the drawings]

FIG. 1 is a partial sectional view showing an oil-cooled screw compressor according to a first embodiment of the present invention.

FIG. 2 is a partial sectional view showing a first state of an oil-cooled screw compressor according to a second embodiment of the present invention.

FIG. 3 is a partial cross-sectional view illustrating a second state of the oil-cooled screw compressor according to the second embodiment of the present invention.

FIG. 4 is a partial sectional view showing a third state of the oil-cooled screw compressor according to the second embodiment of the present invention.

FIG. 5 is a partial sectional view showing a fourth state of the oil-cooled screw compressor according to the second embodiment of the present invention.

FIG. 6 is a partial sectional view showing a conventional oil-cooled screw compressor.

[Explanation of symbols]

Reference Signs List 1, 1A oil-cooled screw compressor 2 hydraulic cylinder 3 spring 4 space 5A, 5B, 5C, 5D pipeline 6A, 6B, 6C, 6D on-off valve 7 throttle means 12 suction port 13 discharge port 14 casing 15 screw rotor 16 Slide valve 17 Hydraulic cylinder 18 Piston rod 19 Stopper 22 Seal member 23 Piston

Claims (2)

[Claims] 1. An oil-cooled screw compressor having a displacement adjusting slide valve coupled to a piston rod of a hydraulic cylinder located on a discharge side, wherein the hydraulic cylinder is a single-acting cylinder type, and a piston is formed by pressure oil. Hydraulic pressure characterized by providing an elastic member that constantly urges the slide valve from the suction side to the discharge side in addition to the hydraulic cylinder, while enabling pressurization only from the discharge side to the suction side. Screw compressor. 2. A plurality of pipelines for guiding hydraulic oil in the hydraulic cylinder to a low-pressure section from different positions in the axial direction of the hydraulic cylinder, and an on-off valve provided in each of the pipelines. The hydraulic screw compressor according to claim 1, wherein: