JP6991222B2 - Screw compressor for commercial vehicles - Google Patents

Description

The present invention relates to a screw compressor for commercial vehicles, which has at least one casing and a pressure release valve.

A screw compressor for a commercial vehicle is already known by the prior art. This type of screw compressor is used, for example, to prepare the compressed air required for a commercial vehicle braking system.

In this regard, in particular, oil-filled compressors, particularly screw compressors, are also known, and in such compressors, control of the oil temperature is a problem. Control of the oil temperature is usually carried out by providing an external oil cooler connected to the oil-filled compressor and oil circulation path via a temperature control valve. In this case, the oil cooler is a heat exchanger having two circulation paths separated from each other, that is, a first circulation path for a hot fluid, that is, a compressor oil, and a second circulation path for a cooling fluid. Is provided. As the cooling fluid, for example, air, mixed water containing an antifreeze agent, or other oil can be used.

The oil cooler must then be connected to the compressor oil circulation through a pipeline or hose, and the oil circulation must be protected against leaks.

In addition, this external volume must be filled with oil, which also increases the total amount of oil. This increases the system inertia. In addition, the oil cooler must be mechanically housed and mounted by a surrounding retainer or a separate retainer, which also requires additional mounting means and thus configuration space. do.

US Pat. No. 4,780,601 (US 4,780,061) already knows a screw compressor with a built-in oil cooling section.

Further, German Patent Application Publication No. 3717493 (DE 37 17 493 A1) discloses a screw compressor device arranged in a compact casing, and the screw compressor device is a screw compressor. It has an oil cooler on the electric motor.

The screw compressor of the type described at the beginning is already known, for example, by German Patented Invention No. 102004060417 (DE 10 2004 060 417 B4).

Therefore, an object of the present invention is to improve the screw compressor for commercial vehicles of the type described at the beginning, and in particular, to enable improved depressurization inside the screw compressor.

According to the present invention, this problem is solved by a screw compressor for a commercial vehicle having the feature of claim 1. According to this, a screw compressor for a commercial vehicle, which has at least one casing and a pressure release valve, is subjected to a spring load with at least one spring and at least one closing element. For commercial vehicles, the spring has a spring force specified to operate the closing element when it reaches a predetermined minimum pressure above atmospheric pressure. The screw compressor of is provided.

The idea underlying the present invention is to stop the decompression process of the screw compressor before the pressure inside the screw compressor drops to the same pressure as the atmospheric pressure or a pressure close to the atmospheric pressure. This makes it possible to prevent the formation of bubbles or the formation of oil bubbles inside the casing of the screw compressor or in the oil pan of the screw compressor. The applicability of being able to close the closure mechanism before reaching atmospheric pressure by providing a spring-loaded closure mechanism in connection with the release valve is compared by the spring and at least one closure element. It can be easily obtained. This makes it possible to reliably prevent the formation of air bubbles in the oil inside the casing.

Further, the spring may be a coil spring. This enables easy and inexpensive manufacturing. Moreover, the handling of such coil springs is relatively easy. The design of standard components of this type is also relatively easy.

The closing element may be a sphere. This makes it possible to achieve a simple and reliable closure of the closure mechanism. Moreover, the spheres are relatively easy to obtain and are also easy to assemble. The spring load of the spring can also be easily realized under the sphere. The dimensions of the spring and sphere can be selected so that they engage and secure to each other, so no corresponding surface fit is required.

The spring-loaded closure mechanism may be located near the inlet tube piece of the screw compressor. In this case, integration into the screw compressor is easy and at the same time advantageous exhaust potential can be achieved through the air inlet.

Further, the closing mechanism to which the spring load is applied may be arranged in the exhaust pipe line from the discharge valve of the screw compressor to the inlet pipe piece. In this area, easy and reliable assembly is possible in, for example, the casing of the screw compressor. Furthermore, it is guaranteed that the atmosphere can be reliably accessed through the air inlet of the screw compressor.

Further details and advantages of the present invention will be described in detail with reference to the illustrated examples.

It is a schematic sectional drawing of the screw compressor by this invention. FIG. 3 is a schematic cross-sectional view of a spring loaded closing mechanism of a pressure release valve for the screw compressor of FIG.

FIG. 1 shows a schematic cross-sectional view of the screw compressor 10 according to the embodiment of the present invention.

The screw compressor 10 has a mounting flange 12 for mechanically mounting the screw compressor 10 to an electric motor (not shown here).

However, an input shaft 14 is shown, through which torque is transmitted from the electric motor to one of both screws 16 and 18, i.e. to the screw 16.

The screw 18 meshes with the screw 16 and is driven by the screw 16.

The screw compressor 10 has a casing 20, in which the main components of the screw compressor 10 are housed.

The casing 20 is filled with oil 22.

An inlet pipe piece 24 is provided on the air inlet side of the casing 20 of the screw compressor 10. In this case, the inlet pipe piece 24 is formed so that the air filter 26 is arranged on the inlet pipe piece. Further, the air inlet pipe piece 24 is provided with an air inlet 28 in the radial direction.

A spring-loaded valve insert 30 is provided in the area between the inlet tube piece 24 and the location where the inlet tube piece 24 is attached to the casing 20, in which case it is configured as an axial seal. Has been done.

Such a valve insert 30 functions as a check valve.

An air supply passage 32 for supplying air to both screws 16 and 18 is provided downstream of the valve insert 30.

An air outlet pipe 34 provided with an ascending pipe 36 is provided on the outlet side of both screws 16 and 18.

A temperature sensor 38 is provided in the region at the end of the riser pipe 36, and the oil temperature can be monitored by this temperature sensor.

Further, the air outlet region is provided with a holder 40 for the air / oil separation element 42.

The holder 40 for the air / oil separation element has the air / oil separation element 42 in the bottom area in the assembled state (as shown in FIG. 1).

Further, a corresponding filter screen or a known filtration and oil separation device 44 is provided inside the air / oil separation element 42, but this is not described in more detail.

The holder 40 for the air / oil separation element has an air outlet opening 46 in the central upper region with respect to the assembled and ready to operate state (ie, as shown in FIG. 1). Is connected to the check valve 48 and the minimum pressure valve 50. The check valve 48 and the minimum pressure valve 50 may be formed as one common valve combined.

Following the check valve 48, an air outlet 51 is provided.

The air outlet 51 is usually connected to a reasonably known compressed air consumer.

An ascending line 52 is provided to guide the separated oil 22 existing in the air / oil separating element 42 back into the casing 20 again, and this rising line is the air / oil separating element 42. A filtration and check valve 54 is provided at a location starting from the holder 40 and migrating into the casing 20.

Downstream of the filtration and check valve 54, a nozzle 56 is provided in the casing hole. The oil return guide line 58 is returned to the region approximately in the middle of the screw 16 or screw 18 to supply the oil 22 to the screw again.

An oil discharge screw 59 is provided in the bottom surface region of the casing 20 in the assembled state. A corresponding oil discharge opening is opened through the oil discharge screw 59, and the oil 22 can be discharged through this opening.

An attachment portion 60 to which the oil filter 62 is attached is also provided in the lower region of the casing 20. The oil 22 is first guided to the temperature control valve 66 via the oil filter inlet passage 64 arranged in the casing 20.

Instead of the temperature control valve 66, an open-loop controller and / or a closed-loop controller that can monitor the oil temperature of the oil 22 in the casing 20 and adjust to a target value may be provided. ..

Downstream of the temperature control valve 66 is the oil inlet of the oil filter 62, which returns the oil 22 back to the screw 18 or back to the screw 16 via the central return guide line 68. Although it is guided, it is also guided back to the oil-lubricated bearing 70 of the shaft 14. A nozzle 72 is also provided in the region of the bearing 70, and this nozzle is provided in the casing 20 so as to communicate with the return guide pipe line 68.

The cooler 74 is connected to the attachment portion 60.

In the upper region (with respect to the assembled state) of the casing 20, a safety valve 76 capable of reducing the excessively high pressure in the casing 20 is located.

A bypass line 78 leading to the pressure release valve 80 is located in front of the minimum pressure valve 50. Air can be returned and guided to the region of the air inlet 28 through the pressure release valve 80, which is controlled by the connection with the air supply passage 32. An air vent valve and a nozzle (reduced diameter portion of the supply line) not shown may be provided in this area.

Further, the oil level sensor 82 can be provided on the outer wall of the casing 20 at substantially the height of the pipeline 34. The oil level sensor 82 may be, for example, an optical sensor, and the sensor signal indicates whether the oil level is above the oil level sensor 82 during operation, or the oil level sensor 82 is exposed, thereby oil. It is configured and tuned to be able to detect if the surface is correspondingly lowered.

In connection with such monitoring, an alarm unit may be provided to issue or convey appropriate error notification or warning to the user of the system.

The functions of the screw compressor 10 shown in FIG. 1 are as follows:
Air is supplied via the air inlet 28 and reaches the screws 16 and 18 via the check valve 30, where the air is compressed. After leaving the screws 16 and 18, the air-oil mixture compressed 5 to 16 times rises through the outlet pipe 34 and through the rising pipe 36, and is directly blown to the temperature sensor 38.

The air, still partially containing oil particles, is then guided through the holder 40 to the air / oil separation element 42 and reaches the air outlet line 51 when the corresponding minimum pressure is reached.

The oil 22 present in the casing 20 is held at the operating temperature via the oil filter 62 and, in some cases, via the heat exchanger 74.

If cooling is not required, the heat exchanger 74 is not used and is not turned on.

The corresponding switch-on is done via the temperature control valve 66. After purification in the oil filter 62, the oil is supplied to the screw 18 or to the screw 16 via the pipeline 68, but also to the bearing 70. The oil 22 is supplied to the screw 16 or the screw 18 via the return guide pipes 52 and 58, in which case the purification of the oil 22 is performed in the air / oil separation element 42.

The torque of an electric motor (not shown) is transmitted to the screw 16 via the shaft 14, and the screw 16 meshes with the screw 18, and the screws 16 and 18 of the screw compressor 10 are driven via the electric motor. ..

Based on the discharge valve 80, which is not shown in detail, the high pressure formed on the outlet side of the screws 16 and 18, for example, in the ready-to-operate state is not confined in the region of the supply line 32, especially when the compressor is started. It is ensured that there is always a low inlet pressure, especially atmospheric pressure, in the region of the supply line 32. Otherwise, when the compressor is started, an extremely high pressure that excessively loads the drive motor may be generated on the outlet side of the screws 16 and 18.

FIG. 2 shows a schematic cross-sectional view of a spring loaded closing mechanism 100 for the discharge valve of the screw compressor 10 of FIG.

In this case, the closing mechanism 100 to which the spring load is applied has the spring 102 and the closing element 104.

The spring 102 is formed as a coil spring.

The closing element 104 is formed as a sphere.

The closing mechanism 100 to which the spring load is applied is arranged in the region of the air passage portion of the screw compressor 10, that is, in this case, it is arranged in the exhaust pipe line from the discharge valve 80 to the inlet pipe piece 24. ..

The spring 102 is in this case formed to have a spring force defined to operate the closing element 104 when a predetermined minimum pressure higher than atmospheric pressure is reached.

The function of the spring-loaded closure mechanism 100 is in this case described as follows:
When the compressor 10 is stopped, it is necessary to exhaust the inside of the casing 20 of the screw compressor 10 to reduce the pressure.

This is done via a pressure release valve.

However, such release pressure should be stopped before reaching atmospheric pressure. This helps prevent the formation of air bubbles in the oil 22.

The pressure inside the casing 20 is maintained above atmospheric pressure by the closing mechanism 100 to which a spring load is applied.

In this case, for example, a value of 1.5 to 2.5 bar can be selected. In particular, it is conceivable that a pressure of about 1.5 bar will be selected.

Such adjustment of the boundary pressure is performed by adjusting and selecting the spring 102 and its spring force.

In this case, when the spring force is no longer sufficient for the internal pressure in the casing 20 of the screw compressor 10 to press the closing element 104 against the force of the spring 102, the sphere 104 operates the closing mechanism and thus the closing mechanism. It is set to prevent further release pressure.

10 screw compressor 12 mounting flange 14 input shaft 16 screw 18 screw 20 casing 22 oil 24 inlet pipe piece 26 air filter 28 air inlet 30 valve insert 32 air supply passage 34 air outlet pipe 36 rising pipe 38 temperature sensor 40 air / oil separation Holder for Element 42 Air / Oil Separation Element 44 Filter Screen or Known Filtering or Oil Separator 46 Air Outlet Opening 48 Check Valve 50 Minimum Pressure Valve 51 Air Outlet 52 Rising Pipeline 54 Filtering and Check Valve 56 Nozzle 58 Oil return guide line 59 Oil discharge screw 60 Attachment 62 Oil filter 64 Oil filter inlet passage 66 Temperature control valve 68 Return guide line 70 Bearing 72 Nozzle 76 Safety valve 78 Bypass line 80 Release valve 82 Oil level sensor 100 Spring load Added closure mechanism 102 Spring 104 Closure element

Claims (4)

A screw compressor (10) for commercial vehicles for producing compressed air, with at least one casing (20) , an air outlet (51) for connection to a compressed air consumer, and a pressure release valve (80). ) And
The pressure release valve (80) does not need to exhaust the inside of the casing (20) of the screw compressor (10) through the air outlet (51) provided for connection with the compressed air consumer. It has a spring-loaded closing mechanism (100) with at least one spring (102) and at least one closing element (104), said spring (102). Has a spring force defined to operate the closing element (104) when the spring reaches a predetermined minimum pressure higher than the atmospheric pressure, the closing element (104) further. The closing element (104) stops the decompression process of the screw compressor (10) before the pressure inside the screw compressor (10) drops to the same pressure as the atmospheric pressure or a pressure close to the atmospheric pressure. A screw compressor (10) for commercial vehicles provided in. The screw compressor (10) according to claim 1, wherein the spring (102) is a coil spring. The screw compressor (10) according to claim 1 or 2, wherein the closing element (104) is a sphere. The closing mechanism (100) to which the spring load is applied is arranged in an exhaust pipe line from the pressure release valve (80) to the inlet pipe piece (24) of the screw compressor (10), according to claim 1. The screw compressor (10) according to any one of up to 3.

Images