GB2036167A - Pump delivery measuring device - Google Patents

Abstract

A delivery-measuring device for measuring the amount delivered by a pump, more particularly a fuel- injection pump, the device comprising a measuring vessel which is filled from the bottom and emptied on from the bottom through a valve and has an overflow pipe at the top, the pump shaft being associated with a pulse counter, characterised in that a bottom liquid-level indicator (24) is adapted to switch an input gate (35) in the control circuit of the pulse counter (4, 12, 37) associated with the pump shaft (2) and a top liquid-level indicator (25, 26, 27) is adapted to open an output gate (36) and a computer unit (38) is adapted to calculate the measured result from the pulses counted when both the input gate (35) and the output gate (36) are closed, and to transmit the result to a display device (40). <IMAGE>

Description

SPECIFICATION Delivery-measuring device The invention relates to a delivery-measuring device for measuring the amount delivered by a pump, more particularly an injection pump, the device comprising a measuring vessel which is filled from the bottom and emptied from the bottom through a valve and has an overflow pipe at the top, the pump shaft being associated with a pulse counter.

In known measuring devices of this kind, the test oil conveyed by the injection pump is delivered by a change-over mechanism either to the return oil circuit or to a graduated measuring glass during a predetermined number of revolutions. The graduated glass is read regulariy and emptied to the zero mark after each measurement.

These measuring devices has a disadvantage in that the zero mark is not reached exactly before the beginning of the measurement. If the graduated glass is emptied by turning, some remaining liquid flows back to the bottom of the glass after it has been turned back into the measuring position. If the glass is emptied by a valve, the resilient seal results in a variable zero mark. The same applies if the glass is emptied by a valve cooperating with a piston which moves in the glass and also indicates the liquid level. In the last-mentioned embodiment, the accuracy may also be impaired by leaks at the piston.

In addition, visual reading results in individual reading errors, and the reading process cannot be made automatic.

An object of the invention is to construct a measuring device such that the zero mark is independent of the method of emptying, and the measuring process can be made automatic. To this end, a bottom liquid-level indicator is adapted to switch an input gate in the control circuit of the pulse counter associated with the pump shaft and a top liquid-level indicator is adapted to calculate the measured result from the pulses counted when both the input gate and the output gate are closed, and to transmit the result to a display device.

In an advantageous embodiment, a number of top liquid-level indicators are provided and a time switch adjustable to a selected time is adapted to cooperate with a storage device in selecting one of the liquid-level indicators.

Other features of the invention will be described in detail hereinafter with reference to an embodiment shown in the drawings, in which: Figure 1 shows the basic device for measuring the delivery of a fuel injection pump, and Figure 2 shows a detail of the electric circuit diagram.

As shown in Fig. 1, an injection pump 3 under test is driven by a unit 1. A pulse wheel 4 is mounted on the drive shaft 2 of pump 3.

A pulse recorder 1 2 supplies a counter 37 with the number of pulses received at wheel 4 i.e. a multible of the number of revolutions of pump 3. When the pump is in operation, the test oil begins to flow in tank 32. An auxiliary pump 33 first pumps the test oil through a line 34 to pump 3. In the case, for example, of a four-cylinder series pump, the six injection lines 5, 6 7, 8 each lead to a test-nozzle holder. The present diagram shows only the injection line 8 and the associated injection nozzle 9. The means for regulating the inlet pressure are not shown. Many injection pumps also have a return lipe from the pump housing.

The amount injected by nozzle 9 flows for a limited time in a jet 10 into a vortex chamber 11 filled with test oil. Valve 1 3 limits the pressure in chamber 11, and the injected oil flows through line 1 4 and a non-return valve 1 5 to two communicating pipes 1 6 and 18.

Chamber 11 and pipe 14 act as a pressure reservoir and prevent foam forming, so that when valve 22 is open the test oil continuously overflows the end of pipe 1 8. If no measurement is being made, valve 22 is opened and the oil flows through the outer pipe 1 9 back into the test-oil tank 32.

If the amount delivered has to be measured at a given speed and at a given set load, a button 39 is pressed for starting the computer unit 38. Pressure on button 39 closes the solenoid valve 21, 22 and the output gate circuit 36. The test oil sprayed by nozzle 9 can no longer overflow the end of pipe 18, but rises in the measuring tube 1 6. The input gate circuit 35 is still open, and does not close until the liquid level in tube 1 6 reaches the bottom liquid-level indicator 24.

Gate circuits 35 and 36 are closed and counter 37 counts the revolutions of pump 3 required for the liquid to rise from the bottom indicator 24 to a preselected top indicator 25, 26 or 27. The preselection is made via a measured-volume preselector 29. If, for example, the liquid reaches the preselected indicator 26, the output gate circuit 36 opens and the revolution counter 37 transmits the counted number of pump revolutions to the computer unit 38. Unit 38 calculates the amount delivered per 1000 revolutions from the measured volume, the speed and the number of teeth on wheel 4 as follows: M = measured volume from indicator 24 to indicator 26 z = number of teeth on wheel 4 a = pulses delivered by wheel 4 while the liquid level is rising from indicator 24 to indicator 26 U = number of revolutions of the injection pump V = amount injected per 1000 revolutions.

a z z 1000 M V= U 1000 M.z V= a The final result (i.e. the amount injected per 1000 revolutions or per 100 revolutions if required) is digitally indicated in display panel 40 and printed on a voucher if required.

The liquid-level indicators 24, 25, 26, 27 preferably comprise a light source in combination with a photo-transistor. The difference in reflection between an empty and a full transparent measuring tube 1 8 is used in known manner, via amplifiers, to produce an external switching pulse. In order to reduce the length of tube 16, the measured volume can be increased by increasing the diameter of the top half 1 7 of the measuring tube. Tube 1 6 is calibrated by moving the liquid-level indicators in the direction of arrow 28. An overflow tube 20 gives protection against overflows in the event of a fault.

Fig. 2 shows those components which operate in direct association with the liquid level in tube 1 6. As a variant, a time switch is used to select the measured volume, so as to obtain a minimum measuring time and a consequently fixed accuracy if the capacity of the injection pump varies.

Before the measurement begins, valve 22 is opened and the liquid level in the measuring tube 1 6 is at line 23. The input gate circuit 35 and the output gate circuit 36 are open.

A minimum measuring time of e.g. 20 seconds is preset at the timing switch 30 and the measuring sequence is initiated by pressing the start button 39 of computer 38. Valve 22 stops the test oil from flowing back at the end of pipe 18, and the output gate circuit 36 is simultaneously closed.

When the liquid rising in tube 1 6 has reached the lowest indicator at line 44, a switching pulse closes the input gate circuit 35. Counter 37 then begins to count the pulses received at wheel 4. Switches 41, 42 and 43 of the measured-volume selector 29 are still open.

However, the switch pulse of indicator 24 also begins the timing sequence in timer 30.

When the preselected time of 20 seconds has been reached and the liquid is at the level of line 45, the next higher liquid-level indicator (i.e. indicator 27 in the present case) is used to determine the measured volume. Accordingly, time switch 30 in co-operation with store 31 closes switch 43. Store 31, when interrogated, reports which indicators 25, 26, 27 have already been covered by the liquid.

The liquid continues to rise above line 45 until it reaches indicator 27, when it opens the output gate circuit 36. This ends the measuring process, since the opening of circuit 36 also results in the opening of valve 22. The measuring tube 1 6 empties through the open end of pipe 1 8 until the liquid drops to the level of line 26. Counter 36 transmits the counted number of pulses to computer 38 and the result is displayed in panel 40.

Claims (3)

1. A delivery-measuring device for measuring the amount delivered by a pump, more particularly an injection pump, the device comprising a measuring vessel which is filled from the bottom and emptied from the bottom through a valve and has an overflow pipe at the top, the pump shaft being associated with a pulse counter, characterised in that a bottom liquid-level indicator is adapted to switch an input gate in the control circuit of the pulse counter associated with the pump shaft and a top liquid-level indicator is adapted to open an output gate and a computer unit is adapted to calculate the measured result from the pulses counted when both the input gate and the output gate are closed, and to transmit the result to a display device.

2. A delivery measuring device according to claim 1, characterised in that a number of top liquid-level indicators are provided and a time switch adjustable to a selected time is adapted to co-operate with a storage device in selecting one of the liquid-level indicators.

3. A metering device constructed and arranged substantially as hereinbefore described and as shown in the figures of the accompanying drawings.