Patent Application
20110123367
The present invention generally relates to embodiments of a device for operating an auxiliary assembly, comprising a housing, of a vehicle, in particular of a utility vehicle, having a drive unit, which comprises a further housing and serves to provide a torque, a shaft for transmitting the torque from the drive unit to the auxiliary assembly, and further relates to a vehicle comprising a device of this kind.
Devices of the general type under consideration are known from the prior art and are used very often to operate auxiliary assemblies in vehicles of all kinds. Typically, a torque must be introduced into the auxiliary assemblies by the drive unit to enable them to be operated. In most cases, the torque is introduced by means of a rotatably mounted shaft, the shaft being connected to a drive unit by way of a coupling. Couplings of all kinds can be used in this context, some examples being rotationally rigid, flexible or clutch-type couplings. Depending on construction, the couplings have various disadvantages, clutch-type couplings tending to exhibit wear, for example, thus making it necessary to replace them regularly, thereby increasing the operating costs of the device and introducing the possibility of unforeseen failures. If it is not necessary to embody the couplings as clutch-type or flexible couplings, rotationally rigid couplings are the means of choice since these are of simple construction and are reliable. In this arrangement, two shafts are connected to one another by means of flanges, using bolts. However, there is a need with such shafts to arrange the shafts to be connected or drive units connecting them in alignment and without an offset. It is furthermore necessary to ensure that the flange profiles of the two flanges are the same to enable them to be connected to one another by means of the bolts. These requirements mean that the couplings lack versatility in use, and it is furthermore difficult to achieve the aligned arrangement for connection of the two shafts, especially in environments that offer very limited space and are difficult to access. The same also applies to exchange if either the auxiliary assembly or the drive unit providing the torque fails and has to be replaced.
It is therefore an object of the present invention at least to reduce the disadvantages of the prior art and to specify a device of the type stated at the outset with the aid of which the drive unit providing the torque can be connected more quickly and more easily to the auxiliary assembly for the purpose of transmitting the torque.
The object is achieved by a device in which the shaft projects into the housing of the auxiliary assembly or into the further housing of the drive unit. The auxiliary assembly can be of any conceivable configuration that can be driven by a torque. The fact that it is possible to dispense with the wear- and fault-prone coupling makes the device more reliable in operation, and service lives are increased through the longer maintenance intervals. Moreover, the device can be embodied in a more space- and weight-saving manner and can be produced at lower cost. Furthermore, it is simpler to connect the torque-providing drive unit to the auxiliary assembly since the shaft has a self-centering action.
An advantageous embodiment of the invention is distinguished by the fact that the shaft is supported in the drive unit by a first section with the aid of bearings, and a second section of the shaft projects from the drive unit and into the housing of the drive unit, and the shaft is connected positively or frictionally to a rotatable component of the drive unit. By virtue of the fact that the shaft projects from one component and into the other part makes the component simple to connect to the other by inserting the shaft into a corresponding aperture in the other component. Since the shaft simultaneously enters into a positive or nonpositive connection with the rotatable component, a torque can be transmitted and the two components are coupled to one another once the drive unit has been connected to the auxiliary assembly. There is no longer any need for special centering and connecting steps in this case.
Advantageously, the drive unit and the auxiliary assembly can be arranged directly adjacent to one another, thus ensuring that little space is taken up. The drive unit and the auxiliary assembly are thus combined into a highly integrated device.
A further embodiment of the invention is distinguished by the fact that the rotatable component is supported by the second section and the bearings arranged in the housing of the drive unit. Support for the rotating component is provided by the shaft and the bearings, and this is advantageous especially because, on the one hand, bearings require space but also, on the other hand, show a tendency for wear and have to be replaced regularly. Furthermore, reducing the number of bearings leads to a reduction in the likelihood of failure. In the drive unit comprising the rotating component, it is possible to dispense with special lubricant circuits for lubricating the bearings, and it is thus possible to simplify the structure. Reducing the number of components and simplifying the structure makes the device as a whole less costly to produce and more reliable to operate. Maintenance intervals are significantly reduced.
The device according to the embodiment of the invention which furthermore has a lubricant delivery means for delivering a lubricant to and in a lubricant circuit, can be developed further in that the lubricant delivery means can be driven by means of the shaft. This makes an additional drive unit or drive lines or transmissions superfluous and, as a result, the device according to the invention is simple and economical to manufacture and it is possible to increase its reliability.
Another embodiment is distinguished by the fact that the delivery means is designed as a pump, in particular as a gear pump or screw pump. Pumps are the means of choice for delivering the lubricant, are easy to procure and are distinguished by high reliability. Gear pumps and screw pumps have the advantage of pulsation-free delivery. In the case of screw pumps, in particular, delivery can be achieved with low noise levels and high rotational speeds, while gear pumps are preferably used when the lubricant has a high viscosity.
The invention can further include a holding section for storing and holding ready the lubricant. This holding section can be a tank or a reservoir. Integrating the holding section directly into the device shortens the distances that have to be bridged, for instance the lubricant lines to the pump. This alone already reduces the susceptibility of the device to faults. Moreover, it is possible to dispense with long external hose lines, which can be damaged by objects in the environment of the device or can be gnawed by animals, such as for example martens, and thus develop leaks.
According to a further advantageous embodiment of the present invention, a bayonet joint is used for connecting and centering the drive unit with respect to the auxiliary assembly. Using a bayonet joint, the drive unit and the auxiliary assembly can be connected to one another and separated from one another quickly and easily without the need for special tools. It is furthermore possible, without any great outlay in terms of manufacture, to bring about centering during the connection of the drive unit to the auxiliary assembly by means of an aperture, into which a corresponding projection projects. This embodiment of the present invention is appropriate especially in the case of installation environments with restricted space, in which it is difficult to use tools.
The invention can further employ a flange unit for connecting the drive unit to the auxiliary assembly. Flange units of this kind for connecting the drive unit to the auxiliary assembly are easy to manufacture and are distinguished by high operational reliability. It is furthermore advantageous if the flange unit, the drive unit and the auxiliary assembly are centered with respect to one another. This centering action is likewise easy to achieve in terms of manufacture, e.g. by means of apertures into which corresponding projections engage. In this connection, it is principally the significant dimensions of the flange which need to be mentioned, e.g. the outside diameter, the centering diameter, the pitch circle diameter of the holes and the number of holes for the passage of the bolts. It is expedient here to embody the flange in accordance with current standards. This ensures that the device can be used to connect many drive units, even when the drive units come from other manufacturers. This widens the area of application of the device and enlarges sales markets. However, it is likewise possible to use customer-specific flanges, thereby enabling the customers concerned also to use their own drive units or auxiliary assemblies which do not have flange joints that are standardized or conform to standards, for example. In particular, the inventive device makes it possible without significant effort to select the size of the compressor in such a way that it meets individual customer requirements.
The drive unit is preferably connected to the auxiliary assembly by means of the shaft. For this purpose, the rotatable component is press-fitted onto the shaft or bolted to the shaft. In this embodiment, not only does the shaft engage in the component in such a way that a torque is transmitted but the connection is embodied in such a way that there is no need to provide further connection points in order to connect the drive unit to the auxiliary assembly. The number of elements required for connection is reduced in this way and the length of the operation required for connection is shortened.
According to another aspect of the present invention, after connection the drive unit and the auxiliary assembly form a common coolant circuit for cooling the drive unit and the auxiliary assembly. In this embodiment, an already existing coolant circuit belonging either to the drive unit or the auxiliary assembly can also be used by the drive unit or the auxiliary assembly which does not have its own coolant circuit. A separate cooling system, in the form of a blower for the drive unit or a ventilation system, for example, can be eliminated. The drive unit is thus largely independent of the ambient temperature. Furthermore, only one coolant circuit has to be controlled, and this makes the structure of the device simpler and more compact overall. Moreover, it is possible to achieve a weight saving and an increase in reliability and a simplification of spare parts storage and of maintenance through the reduction in the number of parts.
The device according to the invention can advantageously be developed further in that the coolant circuit can have a delivery means, in particular a pump, for delivering a coolant, in particular water, in the coolant circuit, and a heat exchanger for dissipating heat from the coolant circuit. In this way, effective cooling of the auxiliary assembly and of the drive unit is achieved in a simple and economical manner. Using water as a coolant has the particular advantage that it is available almost anywhere and does not have any environmentally damaging effects in the event of leaks. As an alternative, other liquid heat transfer media can be used instead of water.
A further embodiment is distinguished by the fact that the drive unit is designed as an electric motor and the auxiliary assembly is designed as a compressor for producing compressed air, as an air conditioning compressor for an air conditioning system for air conditioning the vehicle or as a power steering pump for the purpose of assisting the steering of the vehicle, the electric motor comprising the rotatable component, which is designed as a rotor, and a winding. Electric motors are increasingly the driving means of choice since they output a constant torque in all relevant rotational speed ranges and do not give rise to environmentally damaging exhaust gases in operation. Compressors are components that are frequently used in utility vehicles and motor vehicles, especially for producing compressed air. Air conditioning systems and the air conditioning compressors required for them are likewise used widely and on an increasing scale for comfort requirements and, in particular, to provide drivers of utility vehicles with a workspace which maintains their productivity for as long as possible. Very similar considerations apply to the use of power steering pumps for assisting the steering of the vehicle, and in this case too particularly that of utility vehicles. Using power assistance reduces the effort required when steering and reduces driver fatigue.
It is furthermore advantageous if the electric motor is configured as an asynchronous motor or servo motor and/or has a servo-, frequency converter or inverter, in particular a multi-frequency converter or inverter, which can be arranged in any desired manner. A servo-, frequency converter or inverter serves to generate a voltage of modified amplitude and frequency from an alternating or three-phase voltage of a particular frequency or from a DC voltage. This converted voltage is then used to operate the load, in this case the electric motor, and thus enables the rotational speed of the electric motor to be controlled in an infinitely variable manner. The servo-, frequency converter or inverter can be arranged at any desired location in the vehicle, and this location can be chosen so that the best environmental conditions for operation are provided. In particular, it does not have to be arranged directly at the electric motor. It can be arranged so as to be protected from aggressive media and large temperature fluctuations, for example. The connection between the electric motor and the converter or inverter can in turn be achieved by means of an electrically conducting cable. If a multi-frequency converter is used, a single component can be used to control several electric motors independently of one another, e.g. an electric motor for the compressor and another electric motor to drive further auxiliary assemblies, thus eliminating the need to install a dedicated frequency converter for each electric motor present in the vehicle. This simplifies installation and reduces the space requirement. Moreover, the use of a multi-frequency converter is more economical. Electric motors are often embodied as asynchronous motors since they are maintenance-free and robust.
According to another embodiment of the invention the compressor is designed as a piston-type compressor with a crankshaft. The required compression of the air from atmospheric pressure to the service pressure, which is generally between 12 and 12.5 bar, can be carried out in a single stage using piston-type compressors, allowing a more compact construction in comparison with two-stage oil-free screw-type compressors. At the same time, piston-type compressors with a single-stage action are more advantageous in terms of procurement and have additional advantages over screw-type compressors.
A preferred further development of the present invention is distinguished by the fact that the housing and the further housing are of one-piece design. Covers can be provided at suitable points to allow assembly and maintenance. The one-piece configuration of the housings means that the drive unit and the auxiliary assembly no longer have to be connected to one another by special connecting points. Moreover, this gives a device in which the auxiliary assembly and the drive unit are highly integrated, and this embodiment furthermore makes it possible to configure the housing in a compact and weight-saving manner.
Another aspect relates to a vehicle, in particular a utility vehicle, which comprises a device according to the invention. The above-described advantages of the device according to the invention apply in full also to the vehicle comprising this device.
A preferred illustrative embodiment of the present invention is explained in detail below with reference to the appended drawings, in which:
The device 10 shown in
The piston-type compressor 28 comprises a shaft 30, which is embodied as a crankshaft 32 and is supported by means of bearings 34, in particular rolling contact bearings, although any type of bearings 34 suitable for supporting shafts can be employed. The crankshaft 32 has a first section 36 and a second section 38. The first section 36 extends within the further housing 18 of the piston-type compressor 28, whereas the second section projects from the further housing 18. In the asynchronous motor 24 illustrated, the rotatable component 20 is designed as a rotor 40, which is in turn surrounded by windings 42. The rotor 40 is configured such that, when the asynchronous motor 24 is connected to the piston-type compressor 28, the crankshaft 32 is in positive or, alternatively, frictional engagement with the rotor 40, with the result that the torque provided by the asynchronous motor 24 and hence the shaft power can be transmitted to the crankshaft 32 for the purpose of driving the piston-type compressor 28.
When connected, the housing 14 and the further housing 18 are arranged directly adjacent to one another, are in contact at a contact surface 44 and are attached to one another by means of a flange unit 46 or a bayonet joint 48. Other suitable types of attachment can be used. The rotational speed of the asynchronous motor 24 can be controlled with the aid of a frequency converter or inverter 50.
The device 10 has a coolant circuit 52, by means of which both the piston-type compressor 28 and the asynchronous motor 24 are cooled. The coolant circuit comprises a first channel 54 in housing 14 and a second channel 56 in the further housing 18 as well as a first connecting section 58 and a second connecting section 60, which establish communication between the first and the second channel 54, 56. As illustrated, the connecting sections 58, 60 can extend outside the piston-type compressor 28 and the asynchronous motor 24 and be embodied as flexible hoses or in the form of metallic conduits with only a limited ability for deformation. The connecting sections can furthermore be at least partially combined to form one section. It is furthermore conceivable to arrange and configure the connecting sections 58, 60 within the piston-type compressor 28 and the asynchronous motor 24 such that communication between the first channel 54 and the second channel 56 is established when the piston-type compressor 28 is connected to the asynchronous motor 24. A delivery means 62, in particular a pump 64, is used to deliver a coolant in the coolant circuit 52. In the example illustrated, the pump 64 is arranged in the second connecting section 60, but it can also be positioned in the first connecting section 58, in the first channel 54 or in the second channel 56. To dissipate the heat from the piston-type compressor 28 and the asynchronous motor 24, the device 10 has a heat exchanger 66, which is likewise arranged in the second connecting section 60 in the illustrative embodiment shown. The heat exchanger 66 can also be arranged anywhere within the coolant circuit 52.
A lubricant delivery means 86 is provided on the tapered section 68 of the crankshaft 32, being connected to the crankshaft such that a torque can be transmitted. The crankshaft 32 thus drives not only the piston-type compressor 28 but also the lubricant delivery means 86, which can be configured as an oil pump 90, in particular as a gear pump 92 or as a screw pump 94. The lubricant used is preferably oil, which is stored in a holding section 82 and, via a channel 84, is pumped into the piston-type compressor 28 by the oil pump 90 via a channel that is not shown. The oil then returns to the holding section via another channel, which is not shown, thus forming a closed lubricant circuit. The device furthermore comprises a pressure-limiting valve (not shown) for limiting the pressure and for controlling the quantity of lubricant delivered and/or a pressure-operated switch 88 and/or a level sensor (not shown) for sensing the quantity of lubricant in the device. With the aid of the pressure-limiting valve, a direct connection (short circuit) can be achieved between the suction and the pressure zone of the delivery means if the selected lubricant pressure in the device is exceeded.
The first channel 54 of the coolant circuit 52 is arranged around the windings 42, and a coolant housing is formed at the outside of the windings 42. The coolant housing 70 comprises ribs 72 to increase the surface area which is in contact with the coolant circuit 52 in order to improve heat transfer. An air admission valve 76 is provided to allow air to be admitted to the lubricant circuit of the device 10. To simplify assembly and maintenance of the device 10, it can have a second flange unit 74, which is more easily accessible than flange unit 46. The device 10 has feet 78, by means of which it can be placed on any desired underlying surface (not shown). To prevent the vibration which arises during the operation of the device 10 from being transmitted to the underlying surface, or at least ensure that it is transmitted to only a reduced extent, the feet have vibration absorbers 80. This is helpful especially when the device 10 is used in a vehicle in order to avoid impairing ride comfort.
As an alternative, housing 14 and the further housing can be of one-piece design (not shown); being designed as an integral casting, for example. For assembly and maintenance, covers can be provided at suitable points. In this case, it is no longer necessary for the drive unit and the auxiliary assembly to be connected to one another by special connecting means.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2008 026 227.7 | May 2008 | DE | national |
| 10 2008 049 238.8 | Sep 2008 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP09/01281 | 2/24/2009 | WO | 00 | 1/25/2011 |
