Method for the supply of compressed air to a compressed-air consumer, valve device and data carrier with a computer program

Abstract

A method for the supply of compressed air of a compressed-air consumer having two fluidically separate, kinematically coupled working areas, wherein each of the working areas is assigned to a valve arrangement which can be independently controlled and can be configured between a blocking position, a first functional position for a fluidically communicating connection to a fluid course and a second functional position for a fluidically communicating connection to a fluid sink and wherein each of the two valve arrangements is configured individually depending on a predefinable movement task for the compressed-air consumer and depending, on at least two pressure values from the following group: supply pressure, first working area pressure, second working area pressure, discharge pressure, for a provision of a predefinable developing for a fluid mass flow or for a provision of a predefinable developing for a fluid pressure in the respective working area or for a provision of a predefinable developing of a valve cross-section.

Claims

1. A method for the supply of compressed air to a compressed-air consumer, the compressed air consumer having a first working chamber and a second working chamber, which are fluidically separated, and kinematically coupled, wherein the first working chamber is assigned to a first valve arrangement, wherein the second working chamber is assigned to a second valve arrangement, wherein the first valve arrangement and the second valve arrangement are independently controlled by a process controller for switching the first and second valve arrangement between a blocking position, a first functional position which allows a fluidically communicating connection of the respective working chamber with a fluid source and a second functional position which allows a fluidically communicating connection of the respective working chamber with a fluid sink, the method comprising: providing a movement task for the compressed-air consumer to the process controller; determining with the process controller a supply pressure, a first working chamber pressure, a second working chamber pressure, and a discharge pressure; calculating with the process controller a first a fluid mass flow development in the first working chamber, which is necessary to fulfil the movement task for the compressed air consumer; calculating with the process controller a second fluid mass flow development in the second working chamber, which is necessary to fulfil the movement task for the compressed air consumer; calculating a first flow value for the first valve arrangement based on the supply pressure and the first working chamber pressure and a first flow function, said first flow function being related with the first valve arrangement; calculating a second flow value for the second valve arrangement based on the supply pressure and the second working chamber pressure and a second flow function, said second flow function being related with the second valve arrangement; calculating a first conductivity value based on the first flow value and the first fluid mass flow development; calculating a second conductivity value based on the second flow value and the second fluid mass flow development; determining a first actuating energy for energizing the first valve arrangement; determining a second actuating energy for energizing the second valve arrangement; providing the first actuating energy to the first valve arrangement to set a first fluid mass flow; providing the second actuating energy to the second valve arrangement to set a second fluid mass flow; providing the first fluid mass flow to the first working chamber to fulfil the movement task; and providing the second fluid mass flow to the second working chamber to fulfil the movement task.

2. The method according to claim 1, wherein there is aeration of a first working chamber with a predefinable developing for a first fluid mass flow and ventilation of a second working chamber with a predefinable developing for a second fluid mass flow to occur.

3. The method according to claim 1, wherein there is an aeration of a first working chamber with a predefinable developing for a first fluid pressure and a ventilation of a second working chamber with a predefinable developing for a second fluid mass flow or a predefinable developing for a valve position of the valve arrangement assigned to the second working chamber.

4. The method according to claim 1, wherein a position of an actuator element received in a flexible manner in an actuator housing can be determined using at least one fluid mass flow that flows through one of the valve arrangements.

5. The method according to claim 1, wherein the flow value is determined from the flow function which is related with a quotient of the first fluid pressure and the second fluid pressure and/or wherein the actuating energy is determined using the fluid-related conductivity value and a characteristic valve curve.

6. A data carrier with a program designed to be stored in a processing device of a valve device which initiates a method according to claim 1 during processing in a processor of the processing device.

7. A valve arrangement for the supply of compressed air to a compressed-air consumer, which comprises two fluidically separate, kinematically coupled working areas, wherein each of the working areas is assigned to the valve arrangement that can be independently controlled, wherein each of the valve arrangements comprises a fluid channel that is formed between an inlet connection for a fluidically communicating connection to a fluid source or fluid sink and an outlet connection for a fluidically communicating connection to a compressed-air consumer and a valve element that is arranged in a mobile manner in the fluid channel to influence a cross-section of the fluid channel and which valve element is assigned to an actuating device to change a functional position and a processing device to provide actuating energy to the actuating device, wherein a first pressure sensor is assigned to a first section of the fluid channel between the inlet connection and the valve element and wherein a second pressure sensor is assigned to a second section of the fluid channel between the valve element and the outlet connection, wherein the processing device is designed to carry out the following steps: determining a supply pressure, a first working chamber pressure, a second working chamber pressure, and a discharge pressure; calculating a first fluid mass flow development in the first working chamber, which is necessary to fulfil a movement task for the compressed air consumer; calculating a second fluid mass flow development in the second working chamber, which is necessary to fulfil the movement task for the compressed air consumer; calculating a first flow value for the first valve arrangement based on the supply pressure and the first working chamber pressure and a first flow function, said first flow function being related with the first valve arrangement; calculating a second flow value for the second valve arrangement based on the supply pressure and the second working chamber pressure and a second flow function, said second flow function being related with the second valve arrangement; calculating a first conductivity value based on the first flow value and the first fluid mass flow development; calculating a second conductivity value based on the second flow value and the second fluid mass flow development; determining a first actuating energy for energizing the first valve arrangement; determining a second actuating energy for energizing the second valve arrangement; providing the first actuating energy to the first valve arrangement to set a first fluid mass flow; providing the second actuating energy to the second valve arrangement to set a second fluid mass flow; providing the first fluid mass flow to the first working chamber to fulfil the movement task; and providing the second fluid mass flow to the second working chamber to fulfil the movement task.

8. The valve arrangement device according to claim 7, wherein the valve arrangement is designed as a proportional valve.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) An advantageous embodiment of the invention is illustrated in the drawings, wherein:

(2) FIG. 1 shows a schematic representation of a first embodiment of a fluid system with a valve device and a compressed-air consumer having two kinematically coupled working areas.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(3) A fluid system 1 shown in FIG. 1 is purely designed by way of an example to provide a linear movement, and in order to do this comprises a valve device 2 and a compressed-air consumer 3. By way of an example, the valve device 2 is created as a pneumatic full bridge circuit with a total of four valve elements 4, 5, 6 and 7 each designed as 2/2-way proportional valves, wherein each of the valve elements 4, 5, 6 and 7 is designed, purely by way of an example, as a solenoid valve with a magnetic drive 8, 9, 10 and 11 as an actuating device. In an alternative embodiment (not shown), the actuating device can also be designed as a piezo drive or a magnetostrictive or otherwise suitable drive.

(4) Each of the valve elements 4, 5, 6 and 7 can be switched between two functional positions, in particular a blocking position and an open position, in the event of the suitable application of electrical energy to the assigned magnetic drives 8, 9, 10 and 11. In order to do this, the magnetic drives 8, 9, 10 and 11 are electrically connected to a processing device 19 by means of control lines 15, 16, 17 and 18, forming a component of the valve device 2 and for example comprising a microprocessor or microcontroller.

(5) Each of the valve elements 4, 5, 6 and 7 is connected to fluid junctions 28 to 31 by means of assigned fluid lines 20 to 27 and forms a valve arrangement that is not described in greater detail with the respective fluid lines 20 to 27 that are assigned in pairs. Fluid lines 20 to 23 are known as the first section of a fluid channel of the respective vale element 4, 5, 6 and 7. Fluid lines 24 to 27, however, are known as the second section of a fluid channel of the respective vale element 4, 5, 6 and 7. Fluid lines 20 and 21 both end in a fluid junction 28, fluid lines 22 and 23 both end in fluid junction 30, fluid lines 24 and 25 both end in fluid junction 29 and fluid lines 26 and 27 both end in fluid junction 31.

(6) Purely by way of an example fluid junction 28 is connected to a fluid source 32 by means of a supply line 36 while fluid junction 30 is connected to a fluid outlet by means of an exhaust line 37 that is assigned to a sound absorber 33. Fluid junction 29 forms a first working connection to the valve device 2 and is connected to a fluid connection 39 of compressed-air consumer 3 by means of a first connection line 38 while fluid junction 31 forms a second working connection of the valve line 2 and is connected to a fluid connection 41 of the compressed-air consumer 3 by means of a second connection line 40.

(7) Purely by way of an example there is a provision for a pressure sensor 42 to 45 to be assigned to each of the supply line 36, the exhaust line 37, the first connection line 38 and the second connection line 40, which pressure sensor is designed to record the respective fluid pressure in the assigned line 36, 37. 38 and 40 and to provide a pressure-dependent sensor signal by means of a sensor line 46 to 49 assigned to the processing device 19 in each case. In a further embodiment (not shown), at least one of the pressure sensors is arranged in a housing for the valve device or outside of a housing of this type.

(8) Purely by way of an example, the compressed-air consumer 3 is designed as a double-acting pneumatic cylinder in which a working piston 50 also designated a mobile wall is received in a cylinder recess 51 of a cylinder housing 52 in a linear manner and as a result separated a first variable-size working area 53 from a second variable-size working area 54. For example, the working piston 50 is connected to a piston rod 55 which penetrates the cylinder housing 52 on the front side and can be pushed together with the working piston 50 in a longitudinal direction along a straight movement path 56 relative to the cylinder housing 52.

(9) Purely by way of an example, there will be a description below of which steps are to be carried out in fluid system 1 to effect a movement of the working piston 50 with the coupled piston rod 55 according to the predefinable movement profile. For example, the working piston 50 is to be moved starting from the position according to the representation in FIG. 1 such that a front side of the working piston 50 comes into contact with an inner surface 58 of the cylinder housing 52 arranged opposite. For example, the predefinable movement profile is designed such that initially a uniform acceleration of the working piston 50 occurs up to a predefinable target speed, then uniform movement of the working piston occurs with the target speed maintained and a final braking of the working piston 50 down to a decreasing speed.

(10) A supply of pressurised fluid to working area 54 is needed for the planned movement of the working piston 50 while a removal of fluid from working area 53 is necessary. The provision of predefinable fluid volume flows is expedient to achieve the desired movement profile as this can be used to configure the movement speed for the working piston precisely. Accordingly, for example, control of valve element 4 and valve element 6 is to be provided, wherein the valve element 4 is used to create a fluidically communicating connection between fluid source 32, fluid junction 29 and the second fluid connection 39 and wherein valve element 6 is used to create a fluidically communicating connection between the first fluid connection 41, the fluid junction 31 and the fluid outlet with the assigned sound absorber 33.

(11) In order to carry out the movement of the working piston 50 according to the movement profile set out above, the processing device 19 initially determines the sensor signals in the pressure sensors 42 to 45 in order to calculate the pressure conditions across the two valve elements 4 and 6. These pressure conditions can be used in a subsequent step to determine a flow value for each valve element 4, 6 from the two fluid pressures and a flow function in the processing device 19 for each of the valve elements 4, 6. The flow value determined is then linked to a predefinable fluid volume flow or fluid mass flow which needs to be provided to the respective working area 53, 54 to achieve the desired movement of the working piston 50 according to the movement profile. The result of this link is known as a fluid-related conductivity value and is needed to determine the actuating energy needed for the respective magnetic drive 8, 10. The actuating energy is determined for each of the magnetic drives 8, 10 by linking the fluid-related conductivity value to a characteristic valve curve, in particular one determined by means of an experiment. The actuating energy is then provided to the respective magnetic drive 8, 10 and leads to a movement of the respective valve slider (not described in greater detail) of the respective valve element 4, 6 and therefore to a release of a fluidically communicating connection between the respective fluid junctions 28 and 29 or 31 and 30.

(12) By controlling the respective valve elements 4, 6, a fluid volume flow or a fluid mass flow is configured between the fluid source 32 and the working area 54 and between the working area 53 and the sound absorber 33, which is associated with a change in the pressures in the respective fluid lines 20 to 27. Cyclically recurring determination of the sensor signals from pressure sensors 42 to 45 and the subsequent processing of the pressure conditions according to the procedure mentioned above means the processing device 19 can set the fluid volume flows for both working areas 53, 54 of the compressed-air consumer 3 such that the desired movement profile is complied with for the working piston 50.