System for an Utility Vehicle Comprising a Screw Compressor and an Electric Motor

Abstract

A system for a utility vehicle has a screw compressor and an electric motor. The electric motor drives the screw compressor. The electric motor is connected to the screw compressor by a flange which has at least one cooling connection, and a cooling channel is provided in the flange.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of PCT International Application No. PCT/EP2017/073537, filed Sep. 19, 2017, which claims priority under 35 U.S.C. § 119 from German Patent Application No. 10 2016 011 442.8, filed Sep. 21, 2016, the entire disclosures of which are herein expressly incorporated by reference.

BACKGROUND AND SUMMARY OF THE INVENTION

The present invention relates to a system for a utility vehicle, comprising a screw compressor and an electric motor.

Screw compressors for utility vehicles are already known from the prior art. Such screw compressors are used to provide the compressed air required for, for example, the brake system of the utility vehicle.

In this context, in particular oil-filled compressors, in particular also screw compressors, are known, in the case of which it is necessary to regulate the oil temperature. This is generally realized by virtue of an external oil cooler being provided which is connected to the oil-filled compressor and to the oil circuit via a thermostat valve. Here, the oil cooler is a heat exchanger which has two mutually separate circuits, wherein the first circuit is provided for the hot liquid, that is to say the compressor oil, and the second circuit is provided for the cooling liquid. As cooling liquid, use may for example be made of air, water mixtures with an antifreeze, or another oil.

This oil cooler must then be connected to the compressor oil circuit by way of pipes or hoses, and the oil circuit must be safeguarded against leakage.

This external volume must furthermore be filled with oil, such that the total quantity of oil is also increased. The system inertia is thus increased. Furthermore, the oil cooler must be mechanically accommodated and fastened, either by use of brackets situated in the surroundings or by use of a separate bracket, which necessitates additional fastening means and also structural space.

U.S. Pat. No. 4,780,061 has already disclosed a screw compressor with an integrated oil cooling arrangement.

Furthermore, DE 37 17 493 A1 discloses a screw compressor installation which is arranged in a compact housing and which has an oil cooler on the electric motor of the screw compressor.

DE 10 2010 015 151 A1 has disclosed a compressor flange for a screw compressor.

Furthermore, US 2014/0190674 A1 has disclosed a connecting flange for a heat exchanger of a motor vehicle, which connecting flange has cooling channels.

Furthermore, DE 10 2013 011 061 B3 has disclosed a heat exchanger having a flange connection, wherein the flange connection has a connecting flange which is a die-cast part and which has passage holes, produced by casting, for receiving threaded bolts.

It is the object of the present invention to advantageously further develop a system for a utility vehicle, comprising a screw compressor and an electric motor, in particular such that a space-saving cooling facility for a generic system can be provided.

According to the invention, a system for a utility vehicle comprises a screw compressor and an electric motor, wherein the electric motor drives the screw compressor. The electric motor is connected to the screw compressor by way of a flange, wherein the flange has at least one cooling port, and wherein at least one cooling channel is provided in the flange.

The invention is based on the underlying concept of creating a space-saving cooling facility by virtue of a connecting element, which is cooled, being provided between the screw compressor and electric motor. It is thus no longer necessary to provide air cooling of the electric motor and of the screw compressor. Rather, a cooling facility is created in a targeted fashion directly at the location at which with the greatest heat generation is present in the system. By means of the arrangement of the flange between the electric motor and screw compressor, and owing to the fact that at least one cooling channel is provided in the flange, cooling using a suitable cooling fluid can be made possible.

Provision may be made in particular for the flange to be a separate component. It is thus made possible for corresponding cooling channel geometries to be able to be easily provided in the flange. Both the screw compressor and the electric motor may in this case be, or remain, of a standard design with regard to the mechanical interface, that is to say the corresponding flanges, and require no modification.

The drive shaft for the drive of the screw compressor by the electric motor may be guided in the flange. The heat generated there can thus be easily dissipated via the flange.

The cooling fluid for the flange may be a water-based cooling fluid, in particular cooling water or a mixture of water and a further component, for example methylene glycol or some other suitable antifreeze.

Provision may furthermore be made for the screw compressor to serve for generating compressed air. In particular, the screw compressor may be one which serves for the supply of compressed air to a pneumatic brake installation of a utility vehicle. Through the provision of a screw compressor with an electric motor, it is made possible for such a system to be permitted in the hybrid vehicle in the utility vehicle sector. A highly efficient system can be provided.

The electric motor may have an electric motor flange which is provided for the connection to the flange. Here, the electric motor flange may be an electric motor flange of standard design of the electric motor. An adaptation is thus not necessary, which permits an inexpensive solution.

Provision may be made in particular for the cooling channel of the flange to be open in the direction of the electric motor flange in the assembled state. In this way, direct contact of the cooling fluid with at least the part of the electric motor flange is made possible. In this way, an efficient dissipation of heat from the electric motor via the electric motor flange and the cooling fluid in the cooling channel of the flange can be made possible.

The seal of the cooling channel may be realized for the first time in the assembled state as a result of the assembly of the electric motor flange and flange. In this way, it is easily realized that, in the assembled state of the system, the cooling fluid is intended to and can come into direct contact at least with parts of the electric motor flange.

In particular, provision may furthermore be made for the electric motor to have no separate cooling channel and/or coolant ports. It is hereby ensured that the electric motor requires no special adaptations, which permits inexpensive production and assembly of the system.

Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic sectional illustration of an exemplary embodiment according to the invention for a system for a utility vehicle comprising a screw compressor and an electric motor.

FIG. 2 is a perspective view of the system in the assembled state.

FIGS. 3A, 3B are perspective views of the flange between the screw compressor and the electric motor.

DETAILED DESCRIPTION OF THE DRAWINGS

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

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).

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.

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

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

The housing 20 is filled with oil 22.

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.

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.

Said valve insert 30 serves as a check valve.

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

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

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.

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

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).

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

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 40 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.

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

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

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.

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.

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.

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.

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

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.

The cooler 74 is connected to the attachment piece 60.

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

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 means of a connection to the air feed 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).

Furthermore, approximately at the level of the line 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.

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.

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

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.

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.

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.

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

The corresponding activation is performed by means of the thermostat valve 66. After purification in the oil filter 64, 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.

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.

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.

FIG. 2 shows, in a perspective view, a view of an exemplary embodiment according to the invention of the overall system 1 with the electric motor 5 and the screw compressor 10.

FIG. 3A and FIG. 3B show perspective views of the flange 12 between screw compressor 10 and electric motor 5.

The flange 12 is situated in the middle as connecting part between screw compressor 10 and electric motor 5.

Here, the flange 12 is formed as a separate component which is arranged between the screw compressor 10 and the electric motor 5.

Here, the drive shaft 14 is guided through the central opening 100 of the flange 12.

The flange 12 has a cooling channel 102.

The cooling channel 102 of the flange 12 is, in this case and as can also be seen in the detail in FIG. 3A, open in the direction of the electric motor flange with regard to the assembled arrangement.

The seal of the cooling channel 102 is formed for the first time in the assembled state as a result of the assembly of the electric motor flange and the flange 12.

The electric motor 5 and the electric motor flange have no cooling channel and no coolant ports.

As is also shown in FIG. 2, use is generally made of the coolant of the cooling system of the screw compressor 10. The coolant circulates via the cooling channel 102 (cf. FIG. 3A) in the flange 12 and is conducted to the oil cooler 74 via a rubber hose 108 connected to the cooling ports 104, 106.

After the cooling of the oil, the cooling liquid returns to the vehicle cooling circuit (not shown in any more detail) and, via this, is correspondingly connected via the cooling outlet port 110.

LIST OF REFERENCE SIGNS

• 1 System
• 5 Electric motor
• 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 Central opening
• 102 Cooling channel
• 104 Cooling ports
• 106 Cooling ports
• 108 Rubber hoses
• 110 Cooling outlet port

The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.

Claims

1. A system for a utility vehicle, comprising:

a screw compressor; and

an electric motor, wherein the electric motor drives the screw compressor; and

a flange, wherein

the electric motor is connected to the screw compressor by the flange,

the flange has at least one cooling port, and

at least one cooling channel is provided in the flange.

2. The system as claimed in claim 1, wherein

the flange is a separate component arranged between the electric motor and the screw compressor.

3. The system as claimed in claim 2, wherein

a drive shaft for driving the screw compressor by the electric motor is guided in the flange.

4. The system as claimed in claim 1, wherein

cooling fluid for the flange is water-based, wherein use is made of cooling water or a mixture of water and a further component.

5. The system as claimed in claim 4, wherein

the further component is methylene glycol.

6. The system as claimed in claim 1, wherein

the screw compressor is configured to generate compressed air.

7. The system as claimed in claim 1, wherein

the electric motor has an electric motor flange which is provided for the connection to the flange.

8. The system as claimed in claim 1, wherein

the at least one cooling channel of the flange is open in a direction of the electric motor flange with regard to the assembled arrangement.

9. The system as claimed in claim 1, wherein

a seal of the cooling channel is formed for the first time in the assembled state as a result of the assembly of the electric motor flange and the flange.

10. The system as claimed in claim 1, wherein

the electric motor or the electric motor flange has no cooling channel and/or no coolant ports.