GB1599855A - Apparatus for measuring engine smoke emission - Google Patents
Apparatus for measuring engine smoke emission Download PDFInfo
- Publication number
- GB1599855A GB1599855A GB736378A GB736378A GB1599855A GB 1599855 A GB1599855 A GB 1599855A GB 736378 A GB736378 A GB 736378A GB 736378 A GB736378 A GB 736378A GB 1599855 A GB1599855 A GB 1599855A
- Authority
- GB
- United Kingdom
- Prior art keywords
- speed
- engine
- chart
- electrical
- pen
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M15/00—Testing of engines
- G01M15/04—Testing internal-combustion engines
- G01M15/10—Testing internal-combustion engines by monitoring exhaust gases or combustion flame
- G01M15/102—Testing internal-combustion engines by monitoring exhaust gases or combustion flame by monitoring exhaust gases
- G01M15/108—Testing internal-combustion engines by monitoring exhaust gases or combustion flame by monitoring exhaust gases using optical methods
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Combustion & Propulsion (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Testing Of Engines (AREA)
- Combined Controls Of Internal Combustion Engines (AREA)
Description
(54) APPARATUS FOR MEASURING ENGINE SMOKE EMISSION
(71) We, LESLIE HARTRIDGE LI
MITED, a British Body Corporate, of
Tingewick Road, Buckingham, Buckinghamshire MK18 1EF, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:
This invention relates to apparatus for measuring engine smoke emission. It is especially useful for measuring the smoke emitted by the exhaust systems of diesel engines, fuel-injection engines and ordinary petrol engines in road vehicles, but it is to be understood that it is not restricted to use with such engines.
Among the methods available for measuring engine smoke emission is the so-called lug-down technique which involves running the driving wheels of a vehicle on freerunning rollers under the power of the engine in an appropriate gear. The engine is brought to its maximum speed, or to a speed near maximum speed, whereupon the vehicle brakes are applied to load the engine while keeping the throttle wide open until the engine speed has dropped to a predetermined percentage of the initial speed (for example, to 40% of the initial speed).
During the "lug-down", i.e. the period of time during which the engine speed is reduced by the brake load from its initial maximum or near-maximum value to the predetermined percentage value, the engine smoke emission is continuously measured by a smokemeter, usually of the lightobscuration kind, which feeds an electrical signal proportional to the smoke density to a chart-recorder. The engine speed is also measured - for example by a tachogenerator driven by the free-running rollers on which the vehicle's driving wheels are supported - and an electrical signal proportional to the engine speed is likewise fed to the chart-recorder.
According to one method of using these two signals, both of them are plotted against time on the chart-recorder, two pens being used to do this. Naturally, the rate of deceleration must not exceed a certain level (for example, not greater than a reduction in speed of 10% per second) as otherwise the test will not be valid. An advantage therefore of plotting speed against time on the chart-recorder is that the rate of deceleration can be determined from the slope of the speed trace on the chart. This method has, however, the disadvantage that it is very difficult and time-consuming to construct the "smoke curve" of the engine, i.e.
smoke density plotted as a function of engine speed.
Another method of using the two signals consists in using an x/y chart-recorder with only one pen to plot the measured smoke density directly against engine speed. This then gives the smoke curve. The rate of deceleration during the lug-down is obtained by timing the duration of the test, usually with a stop-watch. But this will give only the average deceleration rate and will not indicate whether the deceleration rate has exceeded the permitted maximum at some point during the test.
In two other respects the smoke density/ engine speed method described above is superior to the first method. First, the smoke density/engine speed method permits the traces of subsequent tests to be superimposed upon each other on the same chart, which is not possible with the first method.
Second, the smoke density/engine speed method facilitates control of the pen so that only that portion of the engine speed range which is of interest need be plotted.
With these considerations in mind, the aim of the present invention is to provide apparatus for measuring engine smoke emission which operates on the better one of the two methods described above, i.e. the smoke density/engine speed method, but which overcomes the problem of detecting whether the deceleration rate during the lug-down has exceed a predetermined permitted maximum.
According to the invention, apparatus for measuring engine smoke emission comprises an x/y chart-recorder having an electrical circuit adapted to receive an electrical signal proportional to the speed of an engine under test and an electrical signal proportional to the density of smoke emitted by the engine exhaust system and to plot those two signals against each other on a chart during a lug-down test on the engine, the said electrical circuit also including a differentiator for differentiating the speed signal to obtain a signal proportional to the rate of change of speed of the engine and a comparator for comparing the latter signal with a reference signal representing the limit or limits of rate of change of speed, the comparator being arranged to prevent recording of a trace should the rate of change of speed signal move outside the said limit or limits.
In this way, a recording is made only when the rate of deceleration of the engine under test is below a predetermined value.
In other words, only those lug-downs - or parts of lug-downs - which are carried out at a satisfactory rate of deceleration of the engine will be recorded by the chartrecorder.
As the driver, mechanic or garage engineer carrying out the test will invariably conduct a number of lug-downs, one after the other, on the engine under test, it will waste his time if he is not able to know that he has exceeded the deceleration rate until he looks at the traces on the chart. The apparatus will therefore normally be provided with indicating means to let him know instantly whenever he exceeds the permitted deceleration rate. Such indicating means can be in the form of a lamp or meter connected electrically to the comparitor in the electrical circuit of the chart-recorder.
It has already been mentioned above that each lug-down involves bringing the engine speed to a maximum or-near-maximum value and then recording the smoke density and engine speed until the latter has dropped to, say, 40% of the said maximum or near-maximum speed. The chart-recorder circuit can therefore include trace-control means which receive the, or a, signal proportional to the engine speed and which act to cause a trace to be recorded on a chart once the engine speed has reached a predetermined upper value (say, 97% of the maximum engine speed) and to prevent the trace being recorded once the engine speed has dropped to a predetermined lower value (say, 37% of the maximum engine speed).
Thus, where the trace is produced by a pen having a solenoid to depress it against a chart and a. spring to lift it off the chart, the trace-control means can be arranged to control the energisation of the solenoid to give the desired result. This overcomes the necessity of manually operating the pen or other tracing element and ensures, in an automatic manner, that only that part of the speed range which is of interest in each lug-down is recorded. Once the pen has lifted off the chart at the end of a lug-down, it will not come down again onto the chart until the engine speed has once again exceeded the predetermined upper value.
After the smoke density/engine speed values of several lug-downs have been recorded on a chart in respect of the same engine, the traces can be compared with a reference curve or trace denoting an acceptable or unacceptable level of smoke emission for that particular engine. Such a comparison can be facilitated by using a chart which has, printed on it, curves representing the maximum permitted level of smoke emission for engines of different sizes.
When the apparatus is fully set up for measuring the smoke emission of an engine, it will therefore generally include:
(a) a pair, or two pairs, of free-running rollers mounted on a stationary base so as to support the driving wheels (or one pair of driving wheels) of a vehicle clear of the ground, there being a tacho-generator connected to one of the rollers so as to produce an electrical signal proportional to the speed of the engine;
(b) a smokemeter having a probe arranged to be inserted in or near the exhaust pipe of the vehicle engine and including electrical means serving to produce an electrical signal proportional to the smoke density;
(c) an x/y chart-recorder as defined above having electrical connections to the tacho-generator and the electrical means of the smokemeter so as to receive their respective signals; and
(d) indicating means connected electrically to the electrical circuit of the chartrecorder to warn the driver whenever the rate of deceleration of the engine exceeds a predetermined maximum value.
In order that the invention may be thoroughly understood, an example of apparatus in accordance with it will now be described with reference to the accompanying drawings, in which:
Figure 1 is a general view of the apparatus showing the way in which various pieces of equipment are electrically and otherwise connected to each other;
Figure 2 is an electrical circuit diagram of the apparatus; and
Figure 3 is a test chart used with the apparatus.
The apparatus is shown in Figure 1 ready for testing the exhaust gas emission from the diesel engine of a road vehicle 10. As such, the drive wheels 12 of the vehicle are resting on a pair, or two pairs, of spaced-apart, parallel, free-running rollers 14, 16 which are supported on a base 18 for rotation about horizontal axes. This arrangement thus lifts the wheels 12 clear of the ground so that they can be driven by the vehicle engine. Rotation of the vehicle wheels will cause rotation of the rollers 14, 16 which are provided with roughened cylindrical surfaces so that slippage between the vehicle wheels 12 and the rollers 14, 16 is reduced to a minimum. A tacho-generator 20 is mechanically connected by a shaft or gearing 22 to the roller 14 so that rotation of the latter will cause corresponding rotation of the rotor of the tacho-generator.The tacho-generator thereby produces an electrical output signal proportional to the speed of the vehicle engine, and this electrical signal is fed along an electrical conductor or conduit 24 to a junction box 26.
Exhaust gas emitted by the vehicle engine during lug-down tests is measured, as to its density, by a smokemeter 28. For this purpose the smokemeter is provided with a probe 30 in the form of a flexible metal tube the free end of which can be inserted into the exhaust pipe 32 of the vehicle engine.
The smokemeter will not be described in detail as its construction can take various forms. All that need be said is that exhaust gas entering the probe 30 from the exhaust pipe 32 is led into a chamber or compartment in the smokemeter where a beam of light is passed through it. The obscuration of the light beam caused by the smoke is measure electrically by a photo-electrical cell in the smokemeter so that electrical means in the latter are able to produce an electrical output signal proportional to the density of smoke in the engine exhaust gas.
This signal is fed from the smokemeter along an electrical conductor or conduit 34.
The supply of electrical power to the smokemeter is effected along a conductor or conduit 36 from a mains supply 38.
The conductor or conduit 34 from the smokemeter 28 leads to a speed unit 40 forming part of, or connected to, an x/y chart-recorder 42. There is also a conductor or conduit 44 leading from the junction box 26 to the speed unit 40 so that the speed signal from the tacho-generator 20 is simi larlv feed into the speed unit. The speed unit 40 comprises an electrical circuit which is adapted to receive the speed signal and smoke density signal from the tachogenerator and smokemeter respectively and to produce corresponding movement of a pen assembly 46 so that the pen produces a trace 48 on a graph 50, the trace 48 representing smoke density plotted against engine speed. Electrical power to the chartrecorder 42 is taken from the mains supply 38 along a conductor or conduit 52.
To enable the driver, mechanical or other person making the test to know whether he or she is keeping the rate of change of engine speed within a predetermined limit, indicating means 54 including a hand-set 55 are electrically connected by a conductor or conduit 56 to the junction box 26.
Figure 2 illustrates the electrical circuit included in the equipment shown in Figure 1. Various components of the circuit have already been mentioned in the description of Figure 1 and have been given the same reference numerals to identify them. Other components not previously mentioned will now be described and their functions explained.
It will be seen that the conductors or conduits 24, 44 and 34 from the tachogenerator 20 and the smokemeter 28 respectively lead to a run/calibrating switch 58 in the speed unit 40. The smoke density signal is conducted from here along a conductor or conduit 60 means 62 controlling movement of the pen assembly 46 along the y-axis in the chart-recorder 42. The engine speed signal goes to the hand-set 55 which contains means 64 for setting the value of the signal representing the maximum speed of the engine to be tested, an on/off automatic pen control 66 connected via a pen relay control circuit 68 to a solenoid or relay 70 which, when energized, brings the pen down into contact with the graph 50 against the action of a spring (not shown), and a "pen-down" manual control switch 72 which also controls the solenoid or relay 70 through the pen relay control circuit 68.A further "pendown" switch 74 is also provided on the speed unit 40. The pen relay control circuit 68 receives its electrical power from the mains supply 38 via a regulator 90 along a conductor or conduit 76.
The engine speed signal passes from the means 64 in the hand-set 55 to a filter circuit 78 which includes a differentiator 80 for differentiating the speed signal to obtain a signal proportional to the rate of change of speed of the engine during each "lugdown". The latter signal is passed via a conductor or conduit 82 to a comparator 84 where it is compared with a reference signal representing the permitted maximum rate of deceleration for the test to be valid, the comparator being arranged to prevent, momentarily and instantly, recording of a trace on the graph 50 should the deceleration rate signal exceed the permitted maximum. It does this by acting on the pen relay control circuit 68 through a conductor or conduit 86.The reference signal on which the comparator depends for its operation is derived from a reference voltage received at the input terminal 88 from a regulator 90 which is connected by a conductor or conduit 92 to the mains supply 38, the regulator being designed to produce a smoothed D.C. output which is also fed to the run/calibrating switch 58 and to a speed detector 94. The comparator also compares the rate of change of speed signal with a zero reference level so as to prevent recording of a trace should the engine accelerate for any reason during the test.
The speed-detector 94 has, as its purpose, to ensure that the pen records only that part of the speed range which is of interest during each lug-down. It receives the filtered speed signal along a conductor or conduit 96 and acts through the pen relay control circuit 68 via the conductor 98 to bring the pen down on the graph 50 once the engine speed has reached 97% of the maximum speed and to cause the pen to lift from thne graph 50 once the engine speed has dropped to 37% of its maximum value.
The filtered speed signal is also fed to a buffer 100 before being passed to a remote speed meter 102 and to means 104 control, ing movement of the pen assembly 46 along the x-axis in the chart-recorder 42.
As already indicated, the driver or mechanic carrying out the test needs to be made aware quickly should the rate of deceleration of the vehicle engine exceed the predetermined maximum limit. In the circuit shown in Figure 2, this is provided for by the inclusion of an indicating lamp 106 which will go out if the said maximum limit is exceeded.
The electrical and electronic components used in the hand-set 55, the pen relay control circuit 68, the filter + differentiator circuit 78, the deceleration comparator 84 and the speed detector 94 have not been described in detail as their construction and operation is well within the province of electronic engineers. Similarly, the x/y chart-recorder 42 is a commerciallyavailable item so that it too has not been described in detail.
Figure 3 shows three typical, superimposed traces 48a, 48b and 48c on a graph 50.
As will be seen, the graph includes preprinted data so that the traces can be readily interpreted. To facilitate the reading of the traces, curves 108 representing possible limits for engines of different sizes as determined by their nominal gas flow in litres per second are printed on the graph.
It will therefore be seen that the invention provides apparatus by which the smoke emission of engines can be measured in an effective, accurate and straightforward way.
WHAT WE CLAIM IS:
1. Apparatus for measuring engine smoke emission comprising an x/y chartrecorder having an electrical circuit adapted to receive an electrical signal proportional to the speed of an engine under test and an electrical signal proportional to the density of smoke emitted by the engine exhaust system and to plot those two signals against each other on a chart during a lug-down test on the engine, the said electrical circuit also including a differentiator for differentiating the speed signal to obtain a signal proportional to the rate of change of speed of the engine and a comparator for comparing the latter signal with a reference signal representing the limit or limits of rate of change of speed, the comparator being arranged to prevent recording of a trace should the rate of change of speed signal move outside the said limit or limits.
2. Apparatus according to claim 1, in which indicating means are included to indicate whenever the permitted rate of change of speed exceeds the said limit or limits.
3. Apparatus according to claim 2, in which the said inidcating means comprise a lamp or meter connected electrically to the comparator in the electrical circuit of the chart-recorder.
4. Apparatus according to any one of claims 1-3, in which the chart-recorder circuit includes trace-control means which receives the, or a, signal proportional to the engine speed and which act to cause a trace to be recorded on a chart once the engine speed has reached a predetermined value and to prevent the trace being recorded once the engine speed has dropped to a predetermined lower value.
5. Apparatus according to claim 4, in which the trace is produced by a pen having a solenoid to depress it against a chart and a spring to lift it off the chart, the tracecontrol means being arranged to control the energisation of the pen solenoid to give the desired result.
6. Apparatus according to any preceding claim, in which the chart has, printed on it, curves representing the maximum permitted level of smoke emission for engines of different sizes.
7. Apparatus according to claim 1 substantially as described herein with reference to the accompanying drawings.
8. Apparatus for measuring the smoke emission of an engine comprising:
(a) a pair, or two pairs, of free-running rollers mounted on a stationary base so as to support the driving wheels (or one pair of driving wheels) of a vehicle clear of the ground, there being a tacho-generator connected to one of the rollers so as to produce an electrical signal proportional to the speed
**WARNING** end of DESC field may overlap start of CLMS **.
Claims (9)
1. Apparatus for measuring engine smoke emission comprising an x/y chartrecorder having an electrical circuit adapted to receive an electrical signal proportional to the speed of an engine under test and an electrical signal proportional to the density of smoke emitted by the engine exhaust system and to plot those two signals against each other on a chart during a lug-down test on the engine, the said electrical circuit also including a differentiator for differentiating the speed signal to obtain a signal proportional to the rate of change of speed of the engine and a comparator for comparing the latter signal with a reference signal representing the limit or limits of rate of change of speed, the comparator being arranged to prevent recording of a trace should the rate of change of speed signal move outside the said limit or limits.
2. Apparatus according to claim 1, in which indicating means are included to indicate whenever the permitted rate of change of speed exceeds the said limit or limits.
3. Apparatus according to claim 2, in which the said inidcating means comprise a lamp or meter connected electrically to the comparator in the electrical circuit of the chart-recorder.
4. Apparatus according to any one of claims 1-3, in which the chart-recorder circuit includes trace-control means which receives the, or a, signal proportional to the engine speed and which act to cause a trace to be recorded on a chart once the engine speed has reached a predetermined value and to prevent the trace being recorded once the engine speed has dropped to a predetermined lower value.
5. Apparatus according to claim 4, in which the trace is produced by a pen having a solenoid to depress it against a chart and a spring to lift it off the chart, the tracecontrol means being arranged to control the energisation of the pen solenoid to give the desired result.
6. Apparatus according to any preceding claim, in which the chart has, printed on it, curves representing the maximum permitted level of smoke emission for engines of different sizes.
7. Apparatus according to claim 1 substantially as described herein with reference to the accompanying drawings.
8. Apparatus for measuring the smoke emission of an engine comprising:
(a) a pair, or two pairs, of free-running rollers mounted on a stationary base so as to support the driving wheels (or one pair of driving wheels) of a vehicle clear of the ground, there being a tacho-generator connected to one of the rollers so as to produce an electrical signal proportional to the speed
of the engine;
(b) a smokemeter having a probe arranged to be inserted in or near the exhaust pipe of the vehicle engine and including electrical means serving to produce an electrical signal proportional to the smoke density;
(c) an x/y chart-recorder as claimed in any preceding claim having electrical connections to the tacho-generator and the electrical means of the smokemeter so as to receive their respective signals; and
(d) indicating means connected electrically to the electrical circuit of the chartrecorder to warn the driver whenever the rate of deceleration of the engine exceeds a predetermined maximum value.
9. Apparatus according to claim 8 substantially as described herein with reference to the accompanying drawings.
Priority Applications (7)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB736378A GB1599855A (en) | 1978-02-23 | 1978-02-23 | Apparatus for measuring engine smoke emission |
ES477920A ES477920A1 (en) | 1978-02-23 | 1979-02-21 | Apparatus for measuring engine smoke emission |
DE19792907136 DE2907136C2 (en) | 1978-02-23 | 1979-02-22 | Device for measuring smoke emissions |
SE7901580A SE442064B (en) | 1978-02-23 | 1979-02-22 | DEVICE FOR METHOD OF EMISSION OF EXHAUST GAS OR SMOKING FROM AN ENGINE |
JP2017379A JPS54126301A (en) | 1978-02-23 | 1979-02-22 | Smoke discharge measuring device of engine |
BE193642A BE874378A (en) | 1978-02-23 | 1979-02-22 | DEVICE FOR MEASURING SMOKE EMISSIONS FROM AN ENGINE |
NL7901444A NL7901444A (en) | 1978-02-23 | 1979-02-23 | SMOKE MEASUREMENT. |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB736378A GB1599855A (en) | 1978-02-23 | 1978-02-23 | Apparatus for measuring engine smoke emission |
Publications (1)
Publication Number | Publication Date |
---|---|
GB1599855A true GB1599855A (en) | 1981-10-07 |
Family
ID=9831697
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB736378A Expired GB1599855A (en) | 1978-02-23 | 1978-02-23 | Apparatus for measuring engine smoke emission |
Country Status (7)
Country | Link |
---|---|
JP (1) | JPS54126301A (en) |
BE (1) | BE874378A (en) |
DE (1) | DE2907136C2 (en) |
ES (1) | ES477920A1 (en) |
GB (1) | GB1599855A (en) |
NL (1) | NL7901444A (en) |
SE (1) | SE442064B (en) |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE9107156U1 (en) * | 1991-06-11 | 1991-07-25 | Hermann electronic Inh. Horst Hermann, 8502 Cadolzburg | Arrangement for an exhaust gas measurement |
WO2008136360A1 (en) * | 2007-04-27 | 2008-11-13 | Horiba, Ltd. | Exhaust gas analyzer |
-
1978
- 1978-02-23 GB GB736378A patent/GB1599855A/en not_active Expired
-
1979
- 1979-02-21 ES ES477920A patent/ES477920A1/en not_active Expired
- 1979-02-22 DE DE19792907136 patent/DE2907136C2/en not_active Expired
- 1979-02-22 JP JP2017379A patent/JPS54126301A/en active Granted
- 1979-02-22 BE BE193642A patent/BE874378A/en unknown
- 1979-02-22 SE SE7901580A patent/SE442064B/en not_active IP Right Cessation
- 1979-02-23 NL NL7901444A patent/NL7901444A/en not_active Application Discontinuation
Also Published As
Publication number | Publication date |
---|---|
SE442064B (en) | 1985-11-25 |
JPS6335932B2 (en) | 1988-07-18 |
NL7901444A (en) | 1979-08-27 |
SE7901580L (en) | 1979-08-24 |
DE2907136A1 (en) | 1979-09-06 |
BE874378A (en) | 1979-06-18 |
DE2907136C2 (en) | 1987-04-23 |
JPS54126301A (en) | 1979-10-01 |
ES477920A1 (en) | 1980-03-01 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
PS | Patent sealed | ||
PE20 | Patent expired after termination of 20 years |
Effective date: 19980524 |