JPS6335932B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a device for measuring the amount of exhaust smoke from an engine. The present invention is particularly useful for measuring smoke emitted by the exhaust systems of road vehicle diesel engines, fuel-injected engines, and conventional gasoline engines, but is limited to use with such engines. It is not something that will be done.

BACKGROUND OF THE INVENTION Among the methods available for measuring engine emissions are the so-called "lagdown" methods. In this method, a vehicle is placed on free-running rollers, and the wheels of the vehicle are driven by the power of an engine that is set in an appropriate gear. The engine is brought to maximum speed or near maximum speed, at which point the vehicle is braked to load the engine, while the throttle is fully opened until the engine speed falls to a predetermined percentage of the initial speed (for example, 40% of the initial speed). keep it in good condition. During this "lag-down" period, during which the engine speed is reduced by the brake load from an initial maximum or near-maximum value to a predetermined percentage value, the engine exhaust gas is controlled by an electrical signal proportional to the smoke concentration. Continuously measure using a light-blocking smoke meter that sends data to a chat recorder. The engine speed is also measured, for example by a tacho generator driven by free-running rollers supporting the drive wheels of the vehicle, and an electrical signal proportional to this engine speed is also sent to the chart recorder.

One method using these two signals is to plot them together against time on a chart recorder using two pens. Of course, the deceleration rate must not exceed a certain level (e.g.
deceleration rate is less than 10% per second), otherwise the test is invalid. Therefore, one advantage of plotting speed versus time on a chart recorder is that the rate of deceleration can be determined from the slope of tracing the speed on the chart. However, this method has the disadvantage that it is very difficult and time consuming to draw an engine "smoke curve" showing the smoke density plotted as a function of engine speed.

Another method using two signals is
Some use X/Y chart recorders to plot smoke density measurements directly against engine speed using only one pen. This becomes the smoke curve. The deceleration rate during the lagdown period is usually determined by measuring the duration of the test using a stopwatch. However, this method only provides an average deceleration rate and does not indicate whether the deceleration rate exceeded the maximum allowable limit at any point during the test.

The smoke density/engine deceleration method described above has two additional
This method is superior to the first method in two respects. First, the smoke density/engine speed method allows you to trace multiple test results on the same chart, whereas the first method does not. The second smoke density/engine speed method allows easy pen control because only the relevant engine speed range needs to be plotted.

PROBLEM SOLVED BY THE INVENTION The present invention operates based on the superior of the two methods described above, namely the smoke density/engine speed method, and the deceleration during the lagdown period exceeds a predetermined tolerance. It is an object of the present invention to provide an engine exhaust gas measurement device that overcomes the problem of detecting whether the exhaust gas has been exceeded.

Means for Solving the Problems According to the present invention, an engine exhaust gas measuring device includes:
Receiving an electrical signal proportional to the speed of the engine being tested and an electrical signal proportional to the concentration of smoke emitted by the engine's exhaust system, the two signals are connected to each other on the chart during an engine lagdown test. an X/Y chart recorder having an electrical circuit adapted to plot the speed signal relative to another; A comparator is provided for comparing this signal with a reference signal representing a limit on the rate of change of velocity, which comparator is connected to a pen relay control circuit which causes recording of the trace to be inhibited whenever the rate of change signal exceeds said limit. It is configured to connect.

Operation With the device of the present invention having the above configuration, recording is performed only when the deceleration rate of the engine under test is below a predetermined value. In other words, only those lagdowns or portions of lagdown that occur at a satisfactory rate of engine deceleration will be recorded on the chart recorder.

It has already been mentioned that each lagdown consists of recording smoke density and engine speed until the engine speed has decreased to, for example, 40% of said maximum value or near maximum value. Therefore, the chart recorder circuit receives a signal proportional to engine speed and causes a trace to be recorded on the chart as soon as the engine speed reaches a predetermined upper limit (e.g., 97% of maximum engine speed), and when the engine speed is Trace control means are provided which act to prevent a trace from being recorded as soon as a predetermined lower limit (eg 39% of maximum engine speed) has been reduced.

EXAMPLE FIG. 1 shows a ready device for testing the exhaust gas emissions from a diesel engine of a road vehicle 10. The drive wheels 12 of the vehicle rest on one or two pairs of parallel, spaced apart self-driving rollers 14, 16 supported on a base 18 for rotation about a horizontal axis. With this arrangement, the wheels 12 are raised off the ground and can therefore be driven by the vehicle's engine in this position. Rotation of the wheels imparts rotation to the rollers 14, 16, and the roughened cylindrical surfaces of the rollers minimize slippage between the wheels 12 and the rollers 14, 16. It's becoming like that. A tacho generator 20 is mechanically connected to the roller 14 by a shaft or transmission 22, and the rotation of the roller imparts a corresponding rotation to the rotor of this tacho generator. The tacho generator thereby generates an electrical output signal proportional to the vehicle engine speed, which electrical signal is transmitted through an electrical conductor or wire 24 to a junction box 26.

During the lag-down test period, the smoke meter 28 measures the concentration of exhaust gas emitted by the vehicle's engine. For this reason, the smoke meter has a flexible metal tube-shaped probe 3.
0 is provided, the free end of which can be inserted into the exhaust pipe 32 of the vehicle's engine. We will not discuss smoke meters in detail since their construction can take many different forms. It should be noted here that the exhaust gases entering the probe 30 from the exhaust pipe 32 are directed into a chamber or partition within the smoke meter where the light beam passes through the exhaust gases. This means that The amount of light ray blockage by the smoke is measured electrically by a photovoltaic cell in the smoke meter, whereby the electrical means in the smoke meter generates an electrical output signal proportional to the smoke concentration in the engine exhaust gas. can do. This signal is sent from the smoke meter by an electrical lead or wire 34. Power is supplied to the smoke meter using power supply 3.
8 through a conductive wire or electric wire 36.

The wire 34 from the smoke meter 28 is
It leads to the Y-chart recorder 42 or to the part forming the speed unit 40 connected thereto. An electric wire 44 also leads from the relay box 26 to the speed unit 40, so that the speed signal from the tacho generator 20 is similarly sent into the speed unit. Speed unit 40
receives speed and smoke density signals from the tacho generator and smoke meter, respectively, and generates corresponding motion of pen assembly 46 to represent smoke density plotted against engine speed on graph 50. Contains electrical circuitry arranged to perform trace 48. Power supplied to the chat recorder 42 is taken from the power supply 38 via a conductor or wire 52.

Display means 54, including a handset 55, to enable the driver, mechanic, or other person performing the test to know whether the rate of change of engine speed is kept within predetermined limits.
is connected to the relay box 2 by a conductor or electric wire 56.
6.

FIG. 2 shows the electrical circuitry contained within the device of FIG. The various components of this circuit have already been described in the description of FIG. 1 and have been provided with the same reference numerals as in FIG. 1 for identification. Below, we will describe the components that have not been mentioned yet and explain their functions.

Conductors or wires 24, 44 and 3 from the tacho generator 20 and the smoke meter, respectively.
4 leads to a run/calibrate switch 58 in the same speed unit 40. The smoke density signal is conducted from there through a lead or wire 60 to a means 62 for controlling movement of the pen assembly 46 along the Y axis of the chart recorder 42. The engine speed signal passes to a handset 55 which includes means 64 for setting the value of the signal representative of the maximum speed of the engine under test;
An on/off switch connected to a solenoid or relay 70 that, when energized via pen relay control circuit 68, lowers the pen into contact with graph 50 against the action of a spring (not shown). An off-style automatic pen control 66 is provided, and a "pen down" manual control switch 72 which also controls a solenoid or relay 70 via a pen relay control circuit 68. Speed unit 4
0 is also provided with another "pen down" switch 74. Pen relay control circuit 68 receives power from power supply 38 via regulator 90 on lead or wire 76 .

The engine speed signal passes from means 64 in the handset 55 to a filter circuit 78 which differentiates the speed signal to obtain a signal proportional to the rate of change of engine speed during each lagdown period. Contains. This signal is sent via conductor or wire 82 to a comparator 84;
Here, the comparator is compared to a reference signal representing the maximum allowable deceleration rate for the test to be valid, and the comparator prevents the recording of the trace on graph 50 at any moment when the deceleration rate signal exceeds the maximum allowable value. It has been adjusted as follows. This is the conductor or wire 8
This is done by acting on the pen relay control circuit 68 via 6. The reference signal that governs the operation of the comparator is derived from a reference voltage received at input terminal 88 from a regulator 90 connected to power supply 38 via conductor or wire 92; The DC output is
8 and speed detector 94. The comparator also compares the speed change rate signal to a zero reference level and is adapted to prevent recording of traces for signals where engine acceleration occurs for any reason during the test period.

The purpose of speed detector 94 is to ensure that the pen records only the relevant portion of the speed range during each lagdown period. The speed detector receives the filtered speed signal via lead or wire 96 and determines whether the engine speed is at maximum speed via a pen relay control circuit 68 on lead 98.
When 97% is reached, the pen is lowered onto the graph 50, and when the engine speed drops to 37% of its maximum value, the pen is lifted off the graph 50.

The filtered speed signal is also buffered 104 before being sent to remote speedometer 102 and means 104 for controlling movement of pen assembly 46 along the X-axis of chart recorder 42.
It is also sent to 00.

As already indicated, the driver or mechanic performing the test needs to be aware quickly if the rate of deceleration of the vehicle's engine exceeds a predetermined maximum limit. In the circuit shown in FIG. 2, this is made possible by providing an indicator lamp 106 which goes out when said maximum limit is exceeded. lamp 106
can also be made to flash after a predetermined maximum allowable test period to prevent overheating of the vehicle's brakes.

handset 55, pen relay control circuit 68,
Filter + differentiator circuit 78, deceleration comparator 84,
The electrical and electrical components of speed detector 94 have not been described in detail since their construction and operation are within the realm of electronic engineers. Similarly, the X/Y chart recorder is commercially available and therefore has not been discussed in detail.

FIG. 3 shows three typical traces 48a, 4
8b and 48c are superimposed on graph 50. As can be seen, the graph also shows pre-printed data to facilitate interpretation of the trace.
To facilitate reading of the trace, a curve 108 printed on the graph shows the possible limits of different sized engines as determined from the normal number of gas flow liters per second.

EFFECTS The present invention operates based on the smoke density/engine speed method and is able to detect whether the deceleration rate exceeds a predetermined tolerance during the lagdown period, thereby reducing the engine deceleration rate below a predetermined value. The engine smoke emissions can be measured effectively and accurately using a simple method.

[Brief explanation of the drawing]

Fig. 1 is an overview of the device of the present invention, showing how the various parts of the device are connected to each other electrically or in other ways, Fig. 2 is an electrical circuit diagram of this device, and Fig. 3 is This is a test chart used for this device. 10: Vehicle, 12: Drive wheel, 14, 16: Running roller, 20: Tacho generator, 28: Smoke meter, 42: X/Y chart recorder, 4
8: Trace, 84: Comparator.

Claims (1)

[Scope of Claims] 1. A device for measuring smoke emissions of an engine, comprising: a device for generating an electrical signal proportional to the speed of the engine under test; and a concentration of smoke emitted by the exhaust system of the engine. a device for generating an electrical signal proportional to , and arranged to receive each electrical signal generated by each of said devices and plot these signals against each other on a chart during an engine lagdown test. It has an X/Y chart recorder with an electric circuit,
The electrical circuit includes 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 this signal with a reference signal representing a predetermined limit value for the rate of change of speed; An apparatus for measuring engine smoke emissions, characterized in that said comparator is connected to a pen relay control circuit which prevents recording of a trace whenever the rate of change signal is outside said limits. 2. Claim 1, wherein the electric circuit is provided with display means for always indicating when the allowable speed change rate exceeds the limit value.
The engine exhaust gas measuring device described in Section 1. 3. The engine exhaust smoke measuring device according to claim 1 or 2, wherein the display means comprises a lamp or a meter electrically connected to a comparator in the electric circuit of the chart recorder.