GB2210473A

GB2210473A - Control of fluid dispensing

Info

Publication number: GB2210473A
Application number: GB8722860A
Authority: GB
Inventors: Michael Andrew Christophe Lowe
Original assignee: Individual
Current assignee: Individual
Priority date: 1987-09-29
Filing date: 1987-09-29
Publication date: 1989-06-07
Also published as: GB8722860D0

Abstract

Fluid such as a lubricant is automatically dispensed when a sensor (12A, 12B) monitoring an operation, e.g. performed by a machine tool, signals that lubricant is required. The sensor senses the position of a reciprocable member of the machine tool and a counter (14) counts the reciprocations and compares the count with an operator set count (16). At coincidence a valve (20) is opened to supply pressurised air to a venturi to dispense lubricant for an operator set duration. <IMAGE>

Description

Dispensing Fluid The present invention relates to the dispensing of fluid and in particular, but not exclusively, to the dispensing of lubrication fluid.

Lubricating fluid is customarily used in machine tools to prevent excessive heating or wear. Carbide tools, for instance, are relatively expensive and must be well lubricated at all times. Accordingly, operators of machine tools using carbide tools are given instructions as to how frequently to apply lubricating fluid. However, it has been observed that unconscientious workers may omit to lubricate as frequently as required by their instructions, either because of laziness or because they are being paid according to the number of items produced by the machine tool, and do not wish to stop the machine in order to lubricate, thereby reducing their earnings.

In consequence, the costs of replacing worn or damaged tools can become unacceptably high, while continued use of worn or damaged tools can lower the quality of the goods being produced.

The present invention has arisen from an appreciation of these problems and the desire to alleviate or avoid them.

According to the present invention there is provided apparatus for dispensing fluid, comprising sensor means and control means operable to cause fluid to be dispensed, the sensor means being operable to monitor an operation and to provide a signal indicative of the result of the monitoring, and the control means being operable in response to the signal to determine in accordance with pre-set conditions when fluid dispensing is required, and to cause fluid to be dispensed at that time.

Preferably the sensor means monitors the movement of a movable member. The movable member may be reciprocable and the signal may indicate when the movable member reaches a pre-determined point in its cycle.

Preferably the control means comprises a counter operable to count each time the signal indicates that the pre-determined point has been reached. The control means may also comprise a comparator operable to compare the accumulated count and a pre-set value, and to cause fluid to be dispensed when the pre-set value is reached. The control means may reset the accumulated count each time fluid is dispensed.

The apparatus preferably comprises an operator control operable to select the pre-set value and/or a display operable to display the pre-set value and/or a display operable to display the accumulated count.

Preferably the apparatus further comprises a venturi nozzle to which the fluid to be dispensed is supplied, and through which the fluid is drawn by the action of a working fluid supplied under the control of the control means. The apparatus preferably comprises an inlet for connection to a supply of pressurized working fluid, a channel for supplying working fluid to the venturi nozzle, and a valve operated by the control means to open or close the channel. Preferably, on each operation, the control means opens the value for a variable pre-set time. The apparatus preferably further comprises means for adjusting the pressure of working fluid supplied to the venturi.

Preferably the apparatus comprises a plurality of venturi nozzles supplied through the channel. The channel preferably branches between the said valve and the venturies, each venturi being supplied by a respective branch, and there may be an override valve in each branch for closing that branch, whereby the override valves may be set to cause selectable venturies or combinations of venturies to be operative. Preferably the override valves are manually operable.

Preferably the sensor means comprises an electrical or magnetic position sensor. The sensor means may for instance comprise a Hall effect probe and a magnet mountable on the movable member.

One embodiment of the present invention will now be described by way of example only and with reference to the accompanying drawings in which: Fig. 1 shows the control panel of the apparatus and the operator controls thereon; Fig. 2 is a schematic diagram of the pneumatic circuit of the apparatus; and Fig. 3 is a block diagram of the electronic circuit of the apparatus.

The drawings show apparatus 10 for dispensing fluid, comprising sensor means 12A,12B and control means 14,16,18 operable to cause fluid to be dispensed. The sensor means 12A,12B are operable to monitor an operation and to provide a signal to the control means, indicative of the result of the monitoring. The control means is operable in response to the signal to determine in accordance with a pre-set condition when fluid dispensing is required, and to cause fluid to be dispensed at that time.

The sensors 12A,12B are Hall effect magnetic sensors. These provide signals to the control means 14,16,18 which in turn control a solenoid valve 20 forming part of a pneumatic circuit by means of which lubricating fluid is dispensed. In more detail, the sensors 12A,12B are located adjacent a machine to be lubricated, in order to detect respective end points of the stroke of a reciprocating member of that machine, such as a piston arm or the like. A small magnet is attached to the reciprocating part so that when the part is at either end of its stroke, one or other sensor 12A,12B causes a signal indicative of the end of the stroke to be provided to the counter 14. That is, a pulse is supplied to the counter 14 twice in each stroke.

The counter 14 includes a divide by two circuit at its input, followed by a resettable counter circuit which is incremented after each complete cycle detected by the sensors 12A,12B.

The accumulated count is provided by the counter 14 at its output 21 which supplies the count to a comparator circuit 16. The comparator circuit 16 compares the count from the counter 14 with a pre-set value manually selected by means of controls shown in Fig. 3. When the comparator 16 determines that the count 20 has reached the pre-set value, a signal is sent on the output 22 to a timing circuit 18. In response to a signal from the comparator 16, the timing circuit 18 provides a pulse of pre-determined duration to a solenoid valve 20 which causes fluid to be dispensed during this period, as will be described. The duration of the timed pulse provided by the circuit 18 is preferably variable, being pre-selected by a further operator control.

The pulse on the output 22 is also fed back to the reset input of the counter 14, to reset the accumulated value to zero.

The accumulated value at 21 is also provided to a LED readout 24 for display.

A manual override switch 26 enables the valve 20 to be manually operated to assist in setting up the apparatus.

The valve 20 forms part of the pneumatic circuit shown in Fig. 2. An inlet for connection to a source of compressed air provides compressed air along a channel 32 to the valve 20. Between the inlet 30 and valve 20, a filter and regulator device 34 is located to control the pressure of the air at the valve 20. The valve 20 is electrically operated and is normally closed except when a pulse is received over the cable 36 from the timing circuit 18.

The channel 32 passes from the valve 20 and branches into four branches 32A,32B,32C,32D which convey air from the valve 20 to a respective venturi nozzle 38.

An override valve 40 is provided in each branch and is manually operable so that the supply to each venturi 38 can be individually opened or closed.

Each venturi 38 is also supplied with lubricating fluid over a supply line 42 in which there is a non-return valve 44.

It will thus be seen that the compressed air acts as a working fluid to draw lubricating fluid through the venturi, so as to. be dispensed.

The operator controls of the apparatus 10 (Fig. 3) comprise a count selector 50 which, in the embodiment shown, comprises two dial wheels which can be rotated to display any number in the range 0 - 99. The number displayed on the count selector 50 is the pre-set value used by the pre-selection circuit 16.

An LED display 52 is the display of the readout circuit 24 and displays the accumulated count provided by the counter 14.

The override button 54 operates a push switch and the manual override switch 26 and can be used to open the valve 20.

Four buttons 56 allow the duration of the pulse from the timing circuit 18 to be selected, according to which button 56 is depressed. In the embodiment shown, the duration can be selected to be 0.5,1,1.5 or 2 seconds. Alternatively, combinations of more than one button can be depressed simultaneously to select longer durations up to a maximum of 5 seconds.

For convenience, the electronic circuitry of Fig. 1 is housed in an upper housing portion 58, with the exception of the sensors 12A,12B and the valve 20. A lower housing portion 60 contains the pneumatic circuit of Fig. 2. The two housings 58,60 are preferably attached together so that the whole apparatus may be suspended from a bracket 62, if desired.

The front of the lower housing 60 mounts the four override switches 40. The valve 20 is housed within the housing 60. The regulator 34 is mounted on and outside the housing 60 and incorporates a control 64 by which the air pressure supply to the valve can be set. A dial 66 displays the pressure being supplied to the valve 20. The branches 32A,32B,32C,32D extend from the override switches 40 within the housing 60 out to the venturies 38, but the branches and venturies are not shown in Fig.

3. The venturies are positioned at appropriate points around the machine being monitored, so that lubricating fluid dispensed through the venturies is applied to the parts needing lubrication.

The apparatus 10 described is set up and used in the following manner. Firstly, the sensors are positioned to detect motion of a reciprocating member of a machine to be monitored and a small magnet is attached to the reciprocating part in order to operate the sensors 12A,12B. The venturies 38 are located around the machine to lubricate where required. If all four venturies 38 are is not necessary to use all four venturies 38, the corresponding override switches 40 are closed, to disable the corresponding venturi 38. Having placed the sensors 12A,12B and venturies 38 in position, the operator then selects the required count by rotating the dials of the count selector 50. In so doing, the operator is selecting the number of machine cycles which will elapse between each occasion on which lubricating fluid is dispensed to the machine.The operator must then select the pulse duration using the buttons 56, and the regulator pressure using the control 64. These two controls combine to determine how much lubricant is dispensed on each occasion, because the air pressure determines the rate at which lubricant is drawn through the venturies, while the duration determines the length of time for which lubricant is dispensed at this rate.

While the venturies 38 are being positioned, and as a final check, the operator may use the manual override switch 26 to open the valve 28, to ensure lubricant is being dispensed to the points required.

The machine is then set in motion, whereupon signals begin to be fed from the sensors 12A,12B to the counter 14, which counts complete machine cycles and displays the count on the display 52. Each time the comparator circuit 16 determines that the required number of cycles has elapsed, the timing circuit 18 is fired to open the valve 20 for the pre-set duration. Compressed air is then supplied through the channel 32 and the branches 32A,32B,32C,32D to the venturies 38, unless disabled by the override switches 40. Lubricant is thus drawn through the venturies and dispensed to the machine until the valve 20 is closed at the end of the period timed by the circuit 18. At the time when the circuit 18 was fired, the pre-selection circuit 16 reset the counter 14 so that the count of machine cycles begin again.The valve 20 will therefore remain closed until the count again reaches the pre-set value.

The non-return valves 44 are used to ensure that the lines to the venturies 38 remain full or virtually full of lubricant even when the valve 20 is closed and there is no air drawing the lubricant up to the venturies.

Various modifications and variations may be made to the apparatus described, without departing from the scope of the present invention. In particular, more or fewer venturies could be used, and different values or ranges of values could be provided for pre-selection for the duration of dispensing and for the selected count.

Moreover, although the invention has been described in relation to the automatic dispensing of lubricant fluid for machine tools, it will be clear from the above description that the apparatus could be applied in other situations where fluid is to be dispensed automatically.

For instance, it is envisaged that the apparatus could be used to control paint spraying nozzles or to supply a releasing agent to a moulding machine.

Whatever the use of the apparatus, it will be seen that it has the advantage that fluid dispensing is automatically performed at the desired time (in terms of the elapsed number of machine cycles) and that each time fluid is dispensed, the desired amount of fluid is dispensed as set by the selected duration and the air pressure. In appropriate circumstances, operator safety may be enhanced, because it would be unnecessary to stop the machine in order to lubricate it, or to apply fluid by hand while the machine is in operation. The ability to ensure correct lubrication is expected to enhance the life of tools and the quality of the manufactured product.

Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.

Claims

1. Apparatus for dispensing fluid, comprising sensor means and control means operable to cause fluid to be dispensed, the sensor means being operable to monitor an operation and to provide a signal indicative of the result of the monitoring, and the control means being operable in response to the signal to determine in accordance with pre-set conditions when fluid dispensing is required, and to cause fluid to be dispensed at that time.

2. Apparatus according to claim 1, wherein the sensor means monitors the movement of a movable member.

3. Apparatus according to claim 2, wherein the movable member is reciprocable and the signal indicates when the movable member reaches a pre-determined point in its cycle.

4. Apparatus according to claim 3, wherein the control means comprises a counter operable to count each time the signal indicates that the pre-determined point has been reached.

5. Apparatus according to claim 4, wherein the control means comprises a comparator operable to compare the accumulated count and a pre-set value, and to cause fluid to be dispensed when the pre-set value is reached.

6. Apparatus according to claim 5, wherein the control means resets the accumulated count each time fluid is dispensed.

7. Apparatus according to claim 5 or 6, and further comprising an operator control operable to select the pre-set value and/or a display operable to display the pre-set value and/or a display operable to display the accumulated count.

8. Apparatus according to any preceding claim, wherein the apparatus further comprises a venturi nozzle to which the fluid to be dispensed is supplied, and through which the fluid is drawn by the action of a working fluid supplied under the control of the control means.

9. Apparatus according to claim 8, wherein the apparatus comprises an inlet for connection to a supply of pressurized working fluid, a channel for supplying working fluid to the venturi nozzle, and a valve operated by the control means to open or close the channel.

10. Apparatus according to claim 9, wherein, on each operation, the control means opens the valve for a variable pre-set time.

11. Apparatus according to any of claims 8 to 10, wherein the apparatus further comprises means for adjusting the pressure of working fluid supplied to the venturi.

12. Apparatus according to any of claims 8 to 11, wherein the apparatus comprises a plurality of venturi nozzles supplied through the channel.

13. Apparatus according to claim 12, wherein the channel branches between the said valve and the venturies, each venturi being supplied by a respective branch.

14. Apparatus according to claim 13, further comprising an override valve in each branch for closing that branch, whereby the override valves may be set to cause selectable venturies or combinations of venturies to be operative.

15. Apparatus according to claim 14, wherein the override valves are manually operable.

16. Apparatus according to any preceding claim, wherein the sensor means comprises any electrical or magnetic position sensor.

17. Apparatus according to claim 16, wherein the sensor means comprises a Hall effect probe and a magnet mountable on the moveable member.

18. Apparatus for dispensing fluid, substantially as described above with reference to the accompanying drawings.

19. Any novel subject matter or combination including novel subject matter herein disclosed, whether or not within the scope of or relating to the same invention as any of the preceding claims.