Patent Application
20140060653
The invention relates to a compressed-air supply device for a utility vehicle and a method for operating a compressed-air supply device.
Compressed-air supply devices fulfill numerous tasks in utility vehicles. These include in particular the supply of the brake system and other compressed air consumers with dried cleaned compressed air, the exercise of a multi-circuit protection valve function for protecting various consumer circuits against each other and for ensuring a certain filling sequence and the provision of a pressure regulator function. The compressed air consumed by the compressed air consumers is primarily provided by a compressor, which is generally driven by the internal combustion engine of the utility vehicle. With numerous systems the compressor can be changed into an energy-saving state, either by separating a coupling via which the compressor can be coupled to the internal combustion engine, or by pneumatically controlling a compressor control input in order to change the compressor into an idling state. Such energy-saving measures can also be supported by carrying out the operating processes in the compressed-air supply device such that compressed air once generated is not lost unnecessarily. Here it is to be noted that a certain loss of compressed air is inevitable, because the filter unit of the compressed-air supply device has to be repeatedly regenerated. For this purpose dry compressed air is passed from the compressed air containers connected to the compressed-air supply devices through the filter unit in a direction that is opposite to the delivery direction. The air flowing through the filter unit at least partly absorbs the moisture in the filter unit in order to then flow into the open via the drain valve of the compressed-air supply device.
In certain systems of the prior art it is provided to couple the energy-saving state to the opening of the drain valve, i.e. whenever the compressor is changed into an energy-saving state the drain valve is also opened, so that thereby an unnecessary loss of pressure occurs in the entire delivery line upstream of a non-return valve facing the consumers and being disposed downstream of the filter unit.
EP 1 318 936 B1 describes a compressed-air supply device that is equipped with a regeneration function and an energy-saving output for changing a compressor into an idling state. Two solenoid valves are provided that implement said functions. It is thereby provided that the opening of the regeneration air path is coupled to the opening of the drain valve. In this way the compressed air is only lost from the volume between the drain valve and a non-return valve disposed downstream of the filter unit and facing the consumers if this is inevitable because of the required regeneration.
DE 10 2007 009 767 B4 discloses a compressed-air supply device with a compressed air input that can be coupled to a compressor, a filter unit coupled to the compressed air input by means of a delivery line, a drain valve coupled to a drain output and the delivery line, an energy-saving control output that can be coupled to a control input of the compressor, a first valve device and a second valve device, wherein the drain valve, the energy-saving control output and the regeneration of the filter unit can be controlled by means of the valve devices, wherein the energy-saving control output can be controlled by the first valve device and the drain valve and the regeneration of the filter unit can be controlled by the second valve device and that the second valve device can be supplied with compressed air by the first valve device. In that the drain valve is only changed into its opened state on initiating the regeneration function, it can be ensured that the volume of compressed air in the delivery line upstream of the non-return valve facing the consumers is only lost if this is inevitable because of the required operating states. It can thus be ensured that when operating the compressed-air supply device only that pressure is lost that is necessary for implementing a regeneration function.
The object of the invention is to provide a compressed-air supply device with changed functionality compared to the prior art.
This object is achieved with a compressed-air supply device, and a method of operating same, for a utility vehicle with a compressed air input that can be coupled to a compressor, a filter unit coupled to the compressed air input via a delivery line, a drain valve coupled to a drain output and the delivery line, an energy-saving control output that can be coupled to a control input of the compressor, and a first valve device and a second valve device. The drain valve, the energy-saving control output and the regeneration of the filter unit can be controlled by the valve devices, wherein the energy-saving control output can be controlled by the first valve device and the drain valve and the regeneration of the filter unit can be controlled via the second valve device. The second valve device can be supplied with compressed air by the first valve device, wherein the first valve device deaerates the control input of a compressor coupled to the energy-saving control output and blocks a supply path to the second valve device in a first switching state and in a second switching state aerates the control input of the compressor coupled to the energy-saving control output and opens the supply path to the second valve. The compressor can be changed into an energy-saving state by aerating the control input, wherein the first valve device is energized in its first switching state and is de-energized in its second switching state.
The invention builds on the compressed-air supply device according to DE 10 2007 009 767 B4 in that the first valve device is energized in its first switching state and is de-energized in its second switching state.
Advantageously, it is provided that the first valve device is a 3/2-way valve, which in a first switching state deaerates the control input of a compressor coupled to the energy-saving output and blocks a supply path to the second valve device and in a second switching state aerates the control input of the compressor coupled to the energy-saving control output and opens the supply path to the second valve. The compressor can be changed into an energy-saving state by aerating the control input. The second valve device is thus only supplied with compressed air if the compressor is changed into its energy-saving state. This is advantageous because the second valve device only has to be active in relation to the other functions of the compressed-air supply device.
It can be provided that the second valve device is a 3/2-way valve which in a first switching state deaerates a control input of the drain valve and blocks a regeneration path and in a second switching state aerates the control input of the drain valve and opens a regeneration path. The drain valve can be changed into an opened state by aerating the control input. In the non-driven state the drain valve is thus closed. Opening only takes place if it is unavoidable because of the regeneration. In that the second valve device is configured as a 3/2-way valve the same as the first valve device, the valve devices can be implemented with the same construction.
It can however also be advantageous that the second valve device is a 2/2-way valve, which in a first switching state deaerates a control input of the drain valve and blocks a regeneration path and in a second switching state aerates the control input of the drain valve and opens a regeneration path. The drain valve can be changed into an opened state by aerating the control input. With regard to providing the functions “opening the regeneration path” and “aerating the drain valve control input”, a 2/2-way valve is sufficient, so that overall a 3/2-way valve and a 2/2-way valve suffice for the compressed-air supply device according to the invention with regard to the present regeneration and energy-saving concept.
By the provision of two valve devices, each with two switching states, there are in all four possible operating states, but because of the supply of the second valve device by the first valve device there are only three relevant operating states, wherein it is provided that in a first operating state of the compressed-air supply device the first valve device adopts its first switching state and the second valve device adopts its first switching state, resulting in a load operating state. The regeneration path is closed, the compressor is in its load phase and the drain valve is closed.
It is further provided that in a second operating state of the compressed-air supply device the first valve device adopts its second switching state and the second valve device adopts its second switching state, resulting in a regeneration operating state. The regeneration air path is opened, the drain valve is opened and the compressor is in its idling phase.
It is further provided that in a third operating state of the compressed-air supply device the first valve device adopts its second switching state and the second valve device adopts its first switching state, resulting in a blocking operating state. The compressor is in its idling phase and the regeneration air path, i.e. a path that bypasses the non-return valve following the filter unit and facing the consumer circuits, is opened. The drain valve is closed, however, so that an outflow of air is prevented.
It is particularly advantageous that an electronic control unit is provided and that the valve devices are solenoid valves. This allows the different operating states of the compressed-air supply device to be adopted based on intelligent calculations, wherein in particular numerous information items relating to the utility vehicle can be taken into account.
The invention builds on the generic method according to DE 10 2007 009 767 B4 in that the first valve device is energized in its first switching state and is de-energized in its second switching state. This enables the advantages and features of the compressed-air supply device according to the invention to be implemented within the framework of a method. This also applies to the particularly preferred embodiments of the method according to the invention given below.
This is particularly characterized in that the first valve device is a 3/2-way valve.
It can also advantageously be provided that the second valve device is a 3/2-way valve that deaerates a control input of the drain valve and blocks a regeneration path in a first switching state and in a second switching state aerates the control input of the drain valve and opens a regeneration path, and that the drain valve is changed into an open state by aerating the control input.
It can also be provided that the second valve device is a 2/2-way valve that deaerates a control input of the drain valve and blocks a regeneration path in a first switching state and in a second switching state aerates the control input of the drain and opens a regeneration path, and that the drain valve is changed into an open state by aerating the control input.
The method according to the invention is developed in an advantageous manner in that in a first operating state of the compressed-air supply device the first valve device adopts its first switching state and the second valve device adopts its first switching state, resulting in a load operating state.
It is further provided that in a second operating state of the compressed-air supply device the first valve device adopts its second switching state and the second valve device adopts its second switching state, resulting in a regeneration operating state.
It is preferred that in a third operating state of the compressed-air supply device the first valve device adopts its second switching state and the second valve device adopts its first switching state, resulting in a blocking operating state.
Advantageously, it is provided that the valve devices are controlled by an electronic control unit.
The invention will now be explained by way of example using particularly preferred embodiments with reference to the accompanying figures.
The solenoid valve 16 is connected to a line 30 that leads to the compressed air container 62 and which is thus under operating brake pressure under normal operating conditions. Another line 32 is connected to the solenoid valve 16, wherein this is connected to the drain output 24. The third connection of the solenoid valve 16 is connected to the energy-saving control output 28 and via a supply path 36 to a first connection of the second solenoid valve 18. A second connection of the second solenoid valve 18 is connected to the drain output 24 via a line 40. The third connection of the solenoid valve 18 is connected via a non-return valve 44 and a choke 38 to a section of the delivery line 46, which is disposed downstream of the filter unit 14 and upstream relative to the non-return valve 42 in relation to the flow direction of the compressed air during the delivery phase. Furthermore, the third connection of the solenoid valve 18 is connected to the control input 34 of the drain valve 20.
If the solenoid valves 16, 18 are de-energized, they adopt their switching state illustrated in the lower part of the valve symbol, whilst the solenoid valves 16, 18 implement the switching state illustrated in the upper part of the valve symbol in the energized state.
If both solenoid valves 16, 18 are de-energized, then the control input of the compressor coupled to the energy-saving control output 28 is deaerated via the line 32 and the drain output 24. The regeneration air path is “doubly blocked”, because on the one hand, because of the de-energized position of the solenoid valve 16, no supply pressure is fed to the solenoid valve 18, and because on the other hand also the solenoid valve 18 causes blocking of the regeneration air path. Because of the lack of supply to the solenoid valve 18 via the supply path 36, a changeover of the second valve device 18 would not be effective.
If both solenoid valves 16, 18 are energized, aeration of the control input of the compressor takes place via the energy-saving control output 28, so that the compressor is changed into its idling state; this is achieved by energizing the valve device 16. By energizing the valve device 18 the control input 34 of the drain valve 20 is operated, so that the drain valve 20 changes over. At the same time the regeneration air path is opened, i.e. a connection is made between the compressed air container 62 and the drain output 24 via the first valve device 16, the second valve device 18, the non-return valve 44, the choke 38, the delivery line section 46, the filter unit 14 and the drain valve 20.
If the first solenoid valve 16 is energized while the second solenoid valve 18 is de-energized the compressor is switched into an idling state by aerating its control input via the energy-saving control output 28. However no regeneration takes place because the regeneration air path is blocked by the solenoid valve 18 and the drain valve 20. A changeover of the compressor into its idling state therefore need not necessarily be accompanied by regeneration, so that the volume of compressed air flowing out during the regeneration is not lost.
Based on the present invention, unnecessary emptying of the line volume between the non-return valve 42 and the drain valve 20 outside the regeneration phases is avoided.
The valve chamber enclosing the constriction 74, as the first regeneration valve chamber 98, is thus sealed against the return chamber 70 of the control piston plate 66 and against a second regeneration valve chamber 76. Said second regeneration valve chamber 76 is separated from the already mentioned valve chamber 60 by means of a further seal 90. The valve chamber 60 is delimited by a valve plate 78, which is pressed against a valve seat by a spring 80. In this way the valve plate 78 seals the valve chamber 60 against an outlet 82.
In all the drain valve 20′ thus comprises five seals, namely the valve seat that interacts with the valve plate 78 and the seals 84, 86, 88, 90 implemented as O-Rings, which interact with the valve housing 72 and seal the control chamber 68, the return chamber 70, the first regeneration valve chamber 98, the second regeneration valve chamber 76 and the valve chamber 60 against each other.
In the switching state illustrated in
The features of the invention disclosed in the above description, in the figures and in the claims can be significant for the realization of the invention both individually and also in any combination.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2011 011 630.3 | Feb 2011 | DE | national |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/EP2012/052587 | Feb 2012 | US |
| Child | 13970345 | US |
