WO2000047901A1

WO2000047901A1 - Control block for controlling the flow of fluid pressure medium to a fluid pressure operated device

Info

Publication number: WO2000047901A1
Application number: PCT/GB2000/000433
Authority: WO
Inventors: Mikal Dreggevik; Jahn Haugstad; Gudmund Rosland
Original assignee: Bryne Mekanikk As
Priority date: 1999-02-15
Filing date: 2000-02-11
Publication date: 2000-08-17
Also published as: GB9903326D0

Abstract

A control block (10, 100) for controlling the flow of fluid pressure medium to a fluid pressure operated device (14), said control block having an inlet (11) for receiving a pumped supply of fluid pressure medium, an outlet (13) for delivery of fluid pressure medium from the control block for supply to the fluid pressure operated device, a flow passage (17, 18; 106) in the control block extending between the inlet and the outlet, a valve element (19, 109) arranged to control the flow through said passage, and an actuator (20, 108) coupled with the valve element and operative to move the valve element between open and closed positions with respect to the passage; a flow monitor which is arranged in the control block (10, 100) to monitor instantaneous rate of flow of fluid pressure medium to the fluid pressure operated device (14), said flow monitor issuing electrical signals representative of the instantaneous rate of flow; an electronic controller (22) which is programmed, or programmable with desired performance data for the operation of the device (14), and which is arranged to receive and to process the electrical signals from the flow monitor.

Description

CONTROL BLOCK FOR CONTROLLING THE FLOW OF FLUID PRESSURE MEDIUM TO A FLUID PRESSURE OPERATED DEVICE

This invention relates to a control block for controlling the flow of fluid pressure medium to a fluid pressure operated device, m which the control block comprises: an inlet for receiving a pumped supply of fluid pressure medium; an outlet for delivering fluid pressure medium from the control block for supply to the fluid operated device; a flow passage m the control block between the inlet and the outlet; a valve element arranged to control the flow through said passage; an actuator connected to the valve element and operable to adjust the valve element between opening and closing positions; and a flow monitor for monitoring the rate of flow of fluid through said outlet.

The invention is primarily concerned with controlling the flow of a liquid pressure medium, e.g. hydraulic oil, to a hydraulically operated device, such as a piston / cylinder device or an hydraulic motor. However, it should be understood that the invention is not restricted to the flow control of liquid pressure medium, but to fluid pressure media generally, including e.g. nitrogen and compressed air.

In the supply of a fluid pressure medium to operate a device, there are many applications m which precise control of the speed of operation of the device is not critical, e.g. the use of a piston / cylinder device (ram) to move a piece of equipment between one position and another. By way of example, a cylinder can be used to rotate a plough beam (carrying pairs of reversible plough bodies) about a substantially horizontal axis between left side ploughing and right side ploughing. The speed of movement of the plough beam is not usually critical, and it is therefore only necessary to ensure that the fluid pressure supplied to the ram is sufficient to move the load (the plough bodies), between one working position and another, within a reasonable time period.

Therefore, to control the supply of fluid pressure, it is only necessary to provide an unsophisticated control valve arrangement which is controlled to be "on" or "off".

However, there are applications in which it is important to supply a fluid pressure medium at a controlled rate, so that a cycle of operation of the fluid pressure operated device can be obtained in which the speed of operation varies according to a required program. For example, in the operation of a ram, it may be desirable to accelerate the piston to a maximum linear speed, and then to decelerate the piston as it approaches the end of its operating stroke so as to provide a "soft" landing.

There are also applications in which it is important to maintain control over the total volume of fluid which is delivered during an operating cycle of a fluid energy consumer (e.g. a ram or an hydraulic motor) .

Therefore, for these two different types of applications (flow rate control and volume control) there is a need to provide a desired performance data for the operation of the device, rather than a simple and unsophisticated type of on / off control.

It is therefore known to provide hydraulic control systems, in which a flow monitor is arranged at a convenient point in a hydraulic circuit, and which gives instantaneous measurement of the rate of flow (which is nearly or approximately proportional to instantaneous speed of operation of the particular device operated by the hydraulic circuit) . It is usual to arrange the flow monitor at a convenient position which is connected to the hydraulically operated device, and the measured value of flow rate can be compared with a desired rate so that compensating adjustment of flow rate can be made if necessary. However, existing types of flow monitor are only available as separate pieces of equipment which are: 1) expensive to purchase, 2) require to be installed at a suitable position in the hydraulic circuit, with the cost and labour of installation using separate fittings, wiring etc.

The invention therefore seeks to provide a control block which can control the flow of a fluid pressure medium to a fluid pressure operated device and which utilises an inexpensive flow monitor which can be incorporated within the control block.

According to the invention there is provided a control block for controlling the flow of fluid pressure medium to a fluid pressure operated device, said control block having an inlet for receiving a pumped supply of fluid pressure medium, an outlet for delivery of fluid pressure medium from the control block for supply to the fluid pressure operated device, a flow passage in the control block extending between the inlet and the outlet, a valve element arranged to control the flow through said passage, and an actuator coupled with the valve element and operative to move the valve element between open and closed positions with respect to the passage; and further including: a flow monitor which is arranged in the control block to monitor instantaneous rate of flow of fluid pressure medium to the fluid pressure operated device, said flow monitor issuing electrical signals representative of the instantaneous rate of flow; an electronic controller which is programmed, or programmable with desired performance data for the operation of the device , and which is arranged to receive and to process the electrical signals from the flow monitor; and an electrical connection between the controller and the actuator to allow the controller to make compensating adjustment of the actuator and of the opening movement of the valve element, when necessary, in order to maintain the desired performance data to operate the fluid pressure operated device.

The invention therefore enables a fluid-pressure operated device, i.e. an energy consumer, such as an hydraulic motor, to have a cycle of operation which is controlled so as to maintain any required operating program (the program may provide for e.g. any particular required graph of instantaneous speed versus time during a cycle of operation) . This is derived by monitoring the rate of flow from the output of the control block, and deriving signals therefrom which are fed to the controller which compares them with instantaneous desired values set by the program, and issue compensating signals to the actuator of the valve element when necessary.

Alternatively, the control block of the invention may be used in volume control of the supply of fluid pressure to operate an energy consumer. In such event, the flow monitor can still be utilised to monitor instantaneous rate of flow, and to generate electrical signals representative of the instantaneous rate of flow. However, the electronic controller will process the signals in a different way, in order to derive actual volume data, and can then compare this with programmed volume data, and make compensating adjustment of the actuator in order to shut off supply to the energy consumer when the desired volume has been reached, e.g. the supply of 1 litre of hydraulic fluid to operate a ram or an hydraulic motor.

The flow monitor can be supplied as a simple and inexpensive component, such as a rotary vane type of impeller, which is preferably mounted as a unit in an outlet port of the control block. The impeller may carry a rotary magnet, or any other convenient means which can generate electrical signals proportional to rotation speed, e.g. as in a tachometer, and such signals can then be supplied to the controller .

The electronic controller can be programmed to provide flow control, volume control or simple ON / OFF control, after processing the signals from the flow monitor.

The control block is preferably of modular form, being built-up from a number of separate valve sections, each controlling the flow of pressure fluid to or from a respective energy consumer.

The control block of the invention may be used in different situations, e.g. (a) to control the rotation of an hydraulic motor being used to rotate a turntable of a bale wrapper apparatus, or (b) to control the linear speed of a turnover cylinder used to reverse the plough bodies of a reversible plough. In some situations, it may be desirable to take into account the load of the piece of machinery which is being operated by the energy consumer (the turntable of the bale wrapper apparatus, or the plough beam carrying the plough bodies in the case of a reversible plough) . Therefore, in a preferred development of the invention, a load-sensing arrangement may be incorporated in the control block, which responds to any particular load, and causes separate adjustment of pressure of fluid to be delivered when the load increases.

A preferred embodiment of control block according to the invention will now be described in detail, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a schematic block diagram of the operating components of a control block according to the invention which is being used to control the flow of hydraulic fluid to operate an hydraulically operated energy consumer device;

Figure 2 is a plan view of an electro-hydraulic modular valve block assembly for use in the control block according to the invention; Figure 3 is a schematic plan view, in exploded form, of the individual valve sections;

Figure 4 is an hydraulic circuit diagram;

Figure 5 is a detailed sectional view showing fluid flow paths through an individual valve section of the valve assembly;

Figure 6 is a sectional view of a flow rate monitoring device located in one of the ports (A or B) of one of the valve sections;

Figure 7 is plan view of an individual valve section; and,

Figure 8 is a sectional view of a valve section plus a preferred load-sensing arrangement also incorporated in the control block, but shown in exploded form for clarity.

Referring now to the drawings, there will be described a control block for controlling the flow of hydraulic pressure to an hydraulically operated device, such as a piston / cylinder device, or an hydraulic motor. However, it should be understood that the control block according to the invention may be used to control the flow of other types of fluid pressure medium to a fluid operated device, and including gases, such as compressed air.

The flow rate is monitored, and instantaneous flow rate data is converted into electrical form, and which is subsequently processed in a way which will depend upon the nature of control which is required. In the case of flow rate control to the fluid energy consume (e.g. a ram or motor) , the instantaneous values of flow rate are compared with programmed desired values, and compensating adjustment is made of the flow of fluid through the control block, when necessary.

In the case of volume control to the fluid energy consumer, e.g. supply of 1 litre of pressure liquid to a ram, the flow rate data is processed into volume data, and is compared with the programmed desired total volume so as to shut-off the flow through the block when the desired volume has been delivered.

Referring first to Figure 1, this is a schematic illustration of the separate components of the control block according to the invention. An electro-hydraulic control block is designated generally by reference, 10 and has an inlet 11 for receiving a pumped supply of fluid pressure medium from pump 12, and an outlet 13 for delivering fluid pressure medium after passage through the control block, for supply to a fluid pressure operated device 14.

In the case of control of hydraulic pressure medium, flow lines 15 connect pump 12 to the inlet 11 of the block 10, and the outlet 13 to the energy consumer 14, after passage along flow passage 17 within the block 10, whereas return flow from the consumer 14 to the tank 16a is via return lines 16 and return passage 18 within the block 10. However, in the case of supply of pneumatic pressure to operate an energy consumer 14, the return lines will go to the block 10, and subsequently be discharged to atmosphere.

In order to control the flow of pumped fluid through the block 10 and to the energy consumer 14, a valve element 19 is arranged within the block 10, and the valve element can be adjusted between fully open and fully closed positions, and also can be adjusted between any required partly open positions, in order to vary the rate of flow to the energy consumer 14 as required.

A valve actuator 20 is coupled with the valve element 19 and operated to move the valve element between open and closed positions with respect to the flow passage 17.

A flow monitor 21 is arranged in the contr'ol block 10 to monitor instantaneously the rate of flow of pressure medium to the energy consumer 14, the flow monitor 21 being arranged to issue electrical signals representative of the rate of flow. An electronic controller 22 is provided which is arranged to receive flow rate signals from the flow monitor 21, and to exert feedback control to the operation of the valve actuator 20. The controller 22 is programmed or programable with desired performance data (e.g. using a data input card) for the cycle of operation of the particular energy consumer 14, and receives and processes the electrical signals from the flow monitor 21 and compares actual flow rate data with desired performance data with which it has been programmed. The controller 22 then makes compensatory adjustment of the actuator 20, to adjust the opening movement of the valve element 19, when necessary (flow rate adjustment in the case of flow rate control to the energy consumer; or shut-off control in the case of volume control of the consumer) .

In the case of flow rate control, the electro-hydraulic control block 10 shown schematically in Figure 1 therefore enables a fluid pressure operated device i.e. an energy consumer such as an hydraulic motor, to have a cycle of operation in which its instantaneous speed during that cycle can be controlled so as to maintain any required operating program. This is achieved by monitoring the rate of flow instantaneously, and deriving signals therefrom, which are fed to the controller which compares them with instantaneous desired values, and issues compensating signals to the actuator when necessary.

The flow monitor 21 can be supplied as a simple and inexpensive product, such as a rotary vane type of impeller, which can generate electrical signals proportional to rotation speed and which are then supplied to the controller. The flow monitor 21 is incorporated within the control block 10, and conveniently in or close to an outlet port of the control block, as will be described in more detail below with reference to the more detailed illustrations of an embodiment of the invention with reference to Figures 2 to 8.

As will be apparent from the detailed drawings, the control block is of modular form, being built up from a number of separate valve sections, each controlling the flow of pressure fluid to or from a respective energy consumer.

Also, bearing in mind that the control block may be used in different situations, e.g. to control the rotation of an hydraulic motor being used to rotate a turntable of a bale wrapper apparatus, or to control the linear speed of a turnover cylinder used to reverse the plough bodies of a reversible plough, in some situations it may be desirable to take into account the load of the piece of machinery which is being operated by the energy consumer.

Therefore, in a preferred development, a load-sensing arrangement is also incorporated in the control block, which responds to any particular load, and causes separate adjustment of the pressure of fluid supplied to the block e.g. to allow a greater pressure of fluid to be delivered when the load increases.

Referring now to Figures 2 and 3, this shows a modular assembly of an electro-hydraulic modular valve block which is designated generally by reference 100, and which is built up from a number of separate valve sections 101, and which are clamped together between inlet section 102 and opposite end section 103. Each section 101 is a directional valve section, which can rout the pressure supply via port A to the energy consumer and return to part B, or vice versa, depending upon its mode of actuation. Figure 4 is an hydraulic circuit diagram showing flow passages to and from pump 104 and tank 105. The individual valve sections 101 are shown, which can take any required number, e.g. up to 15, and each valve section having ports A and B, and an actuator controlled valve element to control fluid flow through the valve section.

Figures 5 to 8 show in detail the operating components of each valve section, and which will now be described. The modular valve block 100 therefore incorporates, in each separate valve section 101, flow and return passages 106 to ports A and B, in order to route flow of hydraulic fluid from pump 104 through the valve section to the energy consumer, back through the valve section and then return to tank 105. A by-pass valve 107 (see Figures 4 and 8), allows the pumped output from pump 104 to pass directly to tank 105 during idle operation of the circuit. In order to control fluid flow through each valve section, an actuator solenoid 108 is operated (see Figure 5) which moves a spool valve 109 and allows pressure fluid to flow along the flow and return passages 106. Depending upon the direction of movement of the spool valve 109, the fluid is discharged via port A t the consumer and returns to port B, or vice versa. The solenoid 108 can be operated in order to open the spool valve 109 by a sufficient amount to provide required flow rate along the passages 106. The flow along the passages 106 then applies pressure against pilot operated check valves 110 and pilot piston 113, and therefore allows flow through the flow and return ports A and B.

A flow monitor 112 (see Fig. 6), comprises an impeller type of unit which can be mounted in either one of the outlet ports A and B, (although show in port A) and its speed of rotation is approximately proportional to the rate of flow of pressure fluid. Depending upon the routing of the fluid, the flow monitored will be flow rate to, or from the consumer. It therefore acting with sensor 114 issues electrical signals which are representative of flow rate, and which are supplied to the electronic controller (shown schematically as 22 in Figure 1) which then compares the actual value with a programmed desired value, and if necessary then sends a compensating feedback electrical command signal to the valve actuator (20 in the schematic illustration of Figure 1), but in practice the actuator solenoid 108 in Figure 5. Depending upon whether the actual flow rate value is above or below the instantaneously required value, the actuator solenoid 108 moves the valve spool 109 to a less open, or more open position accordingly. Desirably, a load sensing arrangement is provided, which is illustrated in more detail in Figure 8, being designated generally by reference 111, and which comprises a pair of shuttle values. This is incorporated in the control block 100, and is arranged to respond to any particular load to be operated by the energy consumer, and causes separate adjustment of the by-pass valve 107, e.g. to allow a greater pressure of fluid to be supplied to the block and to be routed through the block and to the consumer when the load requires a greater pressure supply.

Operation of the Pilot Operated Check Valve

The pilot operated check valve 110 is arranged to open when the inlet pressure exceeds the spring force, and preventing reverse flow of oil. When pressure is applied, in the passage 106, to the pilot piston, it opens the valve on the other side, allowing reverse flow.

This check valve function prevents leakage in the neutral position, e.g. a lifted load will not sink downwards.

Load Sensing Arrangement

The load sensing arrangement has been referred to above, and as shown in Figure 8, being designated generally by reference 111 and 107. This is incorporated in the control block 100 and in the inlet end section 102, and is arranged to respond to any particular load to be operated by the energy consumer, and causes separate adjustment of the valve element e.g. to allow adequate pressure and flow of fluid to be delivered when the load increases.

The arrangement during operation of only one of the valve blocks provides a nearly constant load pressure drop over the inlet port of the valve element (19) operated by the actuator, and prevents excessive pressure in the pump line, and excessive flow of oil is by-passed (107) to the tank. The component shown by reference 111 in Figure 8 is a shuttle valve, which is well known as a valve having two separate seats, and which usually employs balls to seat against one or the other of the two seats.

Therefore, the load sensing arrangement, including shuttle valves (111), responds to varying pressure demand of any particular load, and via internal routing in the control block, as shown in principle in Figure 8, an internal routing to by-pass valve 107, the latter moves accordingly, to allow supply of fluid pressure at a higher, or lower pressure to the control block as necessary, for subsequent delivery to the load, and letting excess flow of oil back to tank.

Claims

1. an electrical connection between the controller (22) and the actuator (20) to allow the controller to make compensating adjustment of the actuator and of the opening movement of the valve element, when necessary, in order to maintain the desired performance data to operate the fluid pressure operated device.

2. A control block according to claim 1, in which the flow monitor is a rotary vane type of impeller.

3. A control block according to claim 1 or 2, which is of modular form, being built-up from a number of separate valve sections 101, each controlling the flow of pressure fluid to or from a respective energy consumer (14).

4. A control block according to any one of claims 1 to

3, including a load-sensing arrangement (111) incorporated in the control block (100), and which is arranged to respond to any particular load, and to cause separate adjustment of the pressure supply of fluid through the block sufficient to meet any load demand.

5. A control block according to any one of claims 1 to

4, in which the electronic controller 22 is programmed, or programmable with desired flow rate performance data for the operation of the device 14, and is arranged to receive and to process the electrical signals from the flow monitor, and to compare actual flow rate data with desired flow rate data, and thereby make compensating adjustment of the actuator and consequent compensating adjustment of the instantaneous actual flow rate.

6. A control block according to any one of claims 1 to 4, in which the electronic controller 22 is programmed, or programmable with volume control data for the supply of fluid pressure to operate the device 14, and is arranged to receive and to process the electrical signals from the flow monitor, and to cause operation of the actuator when actual volume flow reaches desired volume flow and thereby shut-off the flow of fluid to the fluid pressure operated device.

7. A control block according to any one of the preceding claims, and coupled with an hydraulically operated device.

8. A control block according to claim 7, in which the hydraulically operated device comprises a piston / cylinder device, or an hydraulic motor.

9. A control block according to any one of claims 1 to 6, and coupled with a fluid pressure operated device via gas pressure lines.