Screw compressor for a utility vehicle

Abstract

A screw compressor for a utility vehicle has at least one female screw, at least one male screw that meshes with the female screw, and at least one screw compressor drive which drives the female screw.

Claims

1. A screw compressor for a utility vehicle, comprising: a housing; at least one female screw; at least one male screw which meshes with the female screw, wherein the female screw and the male screw are mounted in the housing; oil collected in a bottom portion of the housing, the collected oil directly underlying the at least one female screw and the at least one male screw; a temperature sensor mounted on the housing and at least partially extending outwardly away from the housing, wherein a temperature of the collected oil in the housing is monitorable by the temperature sensor; an oil filter in fluid communication with the collected oil, the oil filter being mounted on the housing and at least partially extending away from the housing external to the housing; a heat exchanger in fluid communication with the oil filter and positioned external to the housing; wherein the collected oil in the bottom portion of the housing is kept at an operating temperature by the oil filter and the heat exchanger; and at least one screw compressor drive positioned external to the housing, wherein the screw compressor drive drives the female screw; an air deoiling element connected to a holder attached to the housing and positioned external to the housing, the air deoiling element being in fluid communication with an air outlet line of the screw compressor defined in the holder; wherein the female screw has an axial coupling and an input shaft and wherein the input shaft is axially driven by the screw compressor drive via the axial coupling, wherein the input shaft passes through an opening in the housing; wherein transmission of torque from the screw compressor drive to the female screw takes place substantially coaxially; wherein the male screw is driven exclusively by the female screw.

2. The screw compressor as claimed in claim 1, wherein a number of teeth of the female screw is greater than that of the male screw.

3. The screw compressor as claimed in claim 2, wherein a transmission ratio of the female screw to the male screw is two to three.

4. The screw compressor as claimed in claim 3, wherein the female screw has six teeth and the male screw has four teeth.

5. The screw compressor as claimed in claim 1, wherein the female screw and the male screw have substantially the same nominal diameter.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a schematic sectional drawing through a screw compressor according to the invention;

(2) FIG. 2 shows a schematic frontal view of the intermeshing male and female screws of the screw compressor; and

(3) FIG. 3 shows a perspective view of the male and female screws as per FIG. 2.

DETAILED DESCRIPTION OF THE DRAWINGS

(4) FIG. 1 shows, in a schematic sectional illustration, a screw compressor 10 in the context of an exemplary embodiment of the present invention.

(5) The screw compressor 10 has a fastening flange 12 for the mechanical fastening of the screw compressor 10 to an electric motor (not shown in any more detail here).

(6) What is shown, however, is the input shaft 14, by which the torque from the electric motor is transmitted to one of the two screws 16 and 18, specifically the screw 16.

(7) The screw 18 meshes with the screw 16 and is driven by means of the latter.

(8) The screw compressor 10 has a housing 20 in which the main components of the screw compressor 10 are accommodated.

(9) The housing 20 is filled with oil 22.

(10) At the air inlet side, an inlet connector 24 is provided on the housing 20 of the screw compressor 10. The inlet connector 24 is in this case designed such that an air filter 26 is arranged at said inlet connector. Furthermore, an air inlet 28 is provided radially on the air inlet connector 24.

(11) In the region between the inlet connector 24 and the point at which the inlet connector 24 joins to the housing 20, there is provided a spring-loaded valve insert 30, which is designed here as an axial seal.

(12) The valve insert 30 serves as a check valve.

(13) Downstream of the valve insert 30, there is provided an air feed channel 32 which feeds the air to the two screws 16, 18.

(14) At the outlet side of the two screws 16, 18, there is provided an air outlet pipe 34 with a riser line 36.

(15) In the region of the end of the riser line 36, there is provided a temperature sensor 38 by means of which the oil temperature can be monitored.

(16) Also provided in the air outlet region is a holder 40 for an air deoiling element 42.

(17) In the assembled state, the holder 40 for the air deoiling element has the air deoiling element 42 in the region facing toward the base (as also shown in FIG. 1).

(18) Also provided, in the interior of the air deoiling element 42, is a corresponding filter screen or known filter and oil separation devices 44, which will not be specified in any more detail.

(19) In the central upper region in relation to the assembled and operationally ready state (that is to say as shown in FIG. 1), the holder for the air deoiling element 42 has an air outlet opening 46 which leads to a check valve 48 and a minimum pressure valve 50. The check valve 48 and the minimum pressure valve 50 may also be formed in one common combined valve.

(20) The air outlet 51 is provided downstream of the check valve 48.

(21) The air outlet 51 is generally connected to correspondingly known compressed-air consumers.

(22) In order for the oil 22 that is situated and separated off in the air deoiling element 42 to be returned again into the housing 20, a riser line 52 is provided which has a filter and check valve 54 at the outlet of the holder 40 for the air deoiling element 42 at the transition into the housing 20.

(23) A nozzle 56 is provided, downstream of the filter and check valve 54, in a housing bore. The oil return line 58 leads back into approximately the central region of the screw 16 or of the screw 18 in order to feed oil 22 thereto again.

(24) An oil drain screw 59 is provided in the base region, in the assembled state, of the housing 20. By means of the oil drain screw 59, a corresponding oil outflow opening can be opened, via which the oil 22 can be drained.

(25) Also provided in the lower region of the housing 20 is the attachment piece 60 to which the oil filter 62 is fastened. Via an oil filter inlet channel 64, which is arranged in the housing 20, the oil 22 is conducted firstly to a thermostat valve 66.

(26) Instead of the thermostat valve 66, it is possible for an open-loop and/or closed-loop control device to be provided by which the oil temperature of the oil 22 situated in the housing 20 can be monitored and set to a setpoint value.

(27) Downstream of the thermostat valve 66, there is then the oil inlet of the oil filter 62, which, via a central return line 68, conducts the oil 22 back to the screw 18 or to the screw 16 again, and also to the oil-lubricated bearing 70 of the shaft 14. Also provided in the region of the bearing 70 is a nozzle 72, which is provided in the housing 20 in conjunction with the return line 68.

(28) The cooler 74 is connected to the attachment piece 60.

(29) In the upper region of the housing 20 (in relation to the assembled state), there is situated a safety valve 76, by which an excessively high pressure in the housing 20 can be dissipated.

(30) Upstream of the minimum pressure valve 50, there is situated a bypass line 78, which leads to a relief valve 80. Via said relief valve 80, which is activated by a connection to the air feed channel 32, air can be returned into the region of the air inlet 28. In this region, there may be provided a ventilation valve (not shown in any more detail) and also a nozzle (diameter constriction of the feeding line).

(31) Furthermore, approximately at the level of the air outlet pipe 34, an oil level sensor 82 may be provided in the outer wall of the housing 20. Said oil level sensor 82 may for example be an optical sensor, and may be designed and configured such that, on the basis of the sensor signal, it can be identified whether the oil level during operation is above the oil level sensor 82 or whether the oil level sensor 82 is exposed, and thus the oil level has correspondingly fallen.

(32) In conjunction with this monitoring, it is also possible for an alarm unit to be provided which outputs or transmits a corresponding error message or warning message to the user of the system.

(33) The function of the screw compressor 10 shown in FIG. 1 is as follows.

(34) Air is fed via the air inlet 28 and passes via the check valve 30 to the screws 16, 18, where the air is compressed. The compressed air-oil mixture, which, having been compressed by a factor of between 5 and 16 downstream of the screws 16 and 18, rises through the outlet line 34 via the riser pipe 36, is blown directly onto the temperature sensor 38.

(35) The air, which still partially carries oil particles, is then conducted via the holder 40 into the air deoiling element 42 and, if the corresponding minimum pressure is attained, passes into the air outlet line 51.

(36) The oil 22 situated in the housing 20 is kept at operating temperature via the oil filter 62 and possibly via the heat exchanger 74.

(37) If no cooling is necessary, the heat exchanger 74 is not used and is also not activated.

(38) The corresponding activation is performed by the thermostat valve 66. After purification in the oil filter 62, oil is fed via the line 68 to the screw 18 or to the screw 16, and also to the bearing 70. The screw 16 or the screw 18 is supplied with oil 22 via the return line 52, 58, and the purification of the oil 22 takes place here in the air deoiling element 42.

(39) By means of the electric motor (not shown in any more detail), which transmits its torque via the shaft 14 to the screw 16, which in turn meshes with the screw 18, the screws 16 and 18 of the screw compressor 10 are driven.

(40) By means of the relief valve 80 (not shown in any more detail), it is ensured that the high pressure that prevails for example at the outlet side of the screws 16, 18 in the operational state cannot be enclosed in the region of the feed line 32, and that, instead, in particular during the start-up of the compressor, there is always a low inlet pressure, in particular atmospheric pressure, prevailing in the region of the feed line 32. Otherwise, upon a start-up of the compressor, a very high pressure would initially be generated at the outlet side of the screws 16 and 18, which would overload the drive motor.

(41) FIG. 2 shows, in a frontal illustration, the intermeshing female screw 16 and the male screw 18.

(42) As can be clearly seen from FIG. 2, the female screw 16 has six screw teeth 100 which are of identical construction and which are distributed uniformly over the circumference.

(43) By contrast, the male screw 18 has four screw teeth 102, which are likewise distributed uniformly over the circumference.

(44) The number of teeth 100 of the female screw 16 is thus greater than that of the male screw 18.

(45) By means of such a design, a transmission ratio of female screw 16 to male screw 18 of two to three is formed.

(46) The female screw 16 and the male screw 18 have substantially the same nominal diameter.

(47) As can also be seen from FIG. 3, which shows a perspective view of the screws 16, 18, the male screw 18 is driven exclusively by the female screw 16.

(48) The female screw 16 is equipped with an axial coupling 104, via which the input shaft 14 of the female screw 16 is driven axially by the screw compressor drive, in this case an electric motor (not illustrated in any more detail).

(49) The screw compressor drive thus drives exclusively the female screw 16.

(50) The transmission of torque from the screw compressor drive to the female screw 16 takes place substantially coaxially.

(51) By means of this embodiment, it is achieved that the rotational speed of the female screw 16 is for example approximately 1000 revolutions per minute, whereas the rotational speed of the male screw 18 is approximately 1500 revolutions per minute (rotational speed ratios at higher or lower rotational speeds assume corresponding values).

(52) It is thus achieved that the rotational speed of the screw compressor drive and of the female screw 16 is identical, whereas the rotational speed of the male screw 18 is considerably higher. In order to maximize the compressed-air generating power, the so-called tip speed, that is to say the speed of the tooth tips, must be selected to be as high as possible, which can be achieved by means of the selected embodiment.

(53) By means of the coaxial transmission of torque from the screw compressor drive to the female screw 16, this is assisted yet further, and furthermore, the mounting of the female and male screws 16, 18 is also greatly simplified.

LIST OF REFERENCE DESIGNATIONS

(54) 10 Screw compressor 12 Fastening flange 14 Input shaft 16 Screws 18 Screws 20 Housing 22 Oil 24 Inlet connector 26 Air filter 28 Air inlet 30 Valve insert 32 Air feed channel 34 Air outlet pipe 36 Riser line 38 Temperature sensor 40 Holder for an air deoiling element 42 Air deoiling element 44 Filter screen or known filter or oil separation devices 46 Air outlet opening 48 Check valve 50 Minimum pressure valve 51 Air outlet 52 Riser line 54 Filter and check valve 56 Nozzle 58 Oil return line 59 Oil drain screw 60 Attachment piece 60a Outer ring 60b Inner ring 62 Oil filter 64 Oil filter inlet channel 66 Thermostat valve 68 Return line 70 Bearing 72 Nozzle 74 Cooler, heat exchanger 76 Safety valve 78 Bypass line 80 Relief valve 82 Oil level sensor 100 Screw teeth 102 Screw teeth 104 Axial coupling