JP7240302B2 - engine test system - Google Patents

Description

The present invention relates to technology for testing engines.

As a technology for testing engines, in a test system in which the output shaft of an internal combustion engine or a reciprocating engine is connected to a dynamometer, the dynamometer and the accelerator opening of the engine are controlled, and the rotational speed and torque of the engine are set as the target of the test conditions. After matching the value, start changing various operation control parameters (fuel injection timing, EGR valve opening, injection pressure, etc.), and fix the accelerator opening while changing the parameters to keep the fuel flow constant. Dynamometer control is performed to keep the engine rotation speed constant while maintaining the engine speed constant, and when the parameter change is completed, the accelerator opening adjustment is restarted so that the engine torque matches the torque of the test conditions. ing.

Here, in this technology, the engine torque at the start of the parameter change is used as a reference torque, and the torque after the start of the parameter change is monitored. It is determined that it has occurred (Patent Document 1).

JP 2016-211868 A

In the above-described engine testing technology, engine misfires are detected from torque fluctuations that may occur due to factors other than misfires, and therefore engine misfires cannot always be detected with high accuracy.

In addition, in this technology, the torque after adjusting the accelerator opening to match the engine speed and torque with the target values of the test conditions is used as the reference torque, and the misfire is detected by the torque fluctuation from the reference torque. Therefore, if a misfire occurs immediately after changing the accelerator opening so that it matches the target value of the test conditions in a region where the accelerator opening is small, the reference torque cannot be properly set and the misfire cannot be detected.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to detect a misfire of an engine with higher accuracy.

In order to achieve the above object, the present invention provides an engine testing system for testing an engine that includes a dynamometer that applies torque to the output shaft of the engine, and a catalyst temperature sensor that detects the temperature of a catalyst that purifies the exhaust gas of the engine. a test control means for executing a measurement process for measuring the state of the engine at each stage while decreasing the throttle opening of the engine in stages; and the temperature of the catalyst detected by the catalyst temperature sensor, a misfire detecting means for detecting a misfire of the engine when the temperature of the catalyst detected by the catalyst temperature sensor when the throttle opening is at the previous stage is increased by a predetermined temperature or more; It is a thing.

According to such an engine test system, the throttle opening at each time point is smaller than the throttle opening at the previous stage. lower than On the other hand, when a misfire occurs in the engine, the amount of unburned gas postburned in the catalyst increases, and the temperature of the catalyst rises. Therefore, by detecting the occurrence of misfire from the temperature rise of the catalyst in the misfire detection means, the occurrence of misfire can be detected more directly and accurately.

Further, in order to achieve the above object, the present invention provides an engine test system for testing an engine, which includes a dynamometer that applies torque to the output shaft of the engine, and a cylinder pressure sensor that detects the cylinder pressure of the cylinder of the engine. a fluctuation rate calculation means for calculating a fluctuation rate of the amount of work per cycle of the cylinder of the engine from the in-cylinder pressure detected by the in-cylinder pressure sensor; However, at each stage, test control means for executing measurement processing for measuring the state of the engine, and misfire of the engine when the fluctuation rate calculated by the fluctuation rate calculation means exceeds a predetermined threshold value. misfire detection means for detecting the

In such an engine test system, in the fluctuation rate calculation means, the value obtained by dividing the standard deviation of the indicated mean effective pressure obtained from the in-cylinder pressure detected by the in-cylinder pressure sensor by the mean of the indicated mean effective pressure is calculated as the engine may be calculated as the variation rate of the work per cycle of the cylinder.

Here, if misfires occur and do not occur in each cycle of the engine, the rate of change in the amount of work per cycle of the cylinders of the engine increases. A misfire can be detected more directly and accurately by detecting the misfire from the fluctuation rate of the work of the cylinder of the engine by the detecting means.

Further, the engine test system is provided with a catalyst temperature sensor for detecting the temperature of a catalyst that purifies the exhaust gas of the engine, and the misfire detection means detects the temperature of the catalyst detected by the catalyst temperature sensor and the throttle opening. A misfire of the engine may also be detected when the temperature of the catalyst detected by the catalyst temperature sensor at the previous stage of opening has risen by a predetermined temperature or more.

Further, the engine test system is further provided with a torque sensor for detecting torque acting between the engine and the dynamometer, and the test control means controls the rotational speed of the engine to a predetermined rotational speed. A dynamometer is controlled, and in the misfire detection means, the direction of the torque detected by the torque sensor is the torque acting to rotate the output shaft of the engine in the forward rotation direction of the engine, that is, the direction opposite to the forward rotation direction. Orientation may detect a misfire of the engine.

Here, in the above engine test system, if the misfire detection means detects a misfire in the test control means, the throttle opening of the engine is stopped to be reduced in stages, and the throttle opening of each of the engines is stopped. It may be configured to increase the degree of opening.

Further, in the above engine test system, the combustion lower limit throttle opening that detects the throttle opening at the stage immediately before the misfire is detected by the misfire detection means as the combustion lower limit throttle opening that is the minimum opening of the throttle that does not cause misfire. Throttle opening detection means may be provided.

As described above, according to the present invention, engine misfire can be detected with higher accuracy.

It is a figure showing composition of an engine testing system concerning an embodiment of the present invention. 1 is a block diagram showing the configuration of a control/measurement system of an engine testing system according to an embodiment of the present invention; FIG. 4 is a flowchart showing measurement sequence control processing according to the embodiment of the present invention; 3 is a block diagram showing the configuration of a misfire detection section according to the embodiment of the present invention; FIG. 4 is a flowchart showing misfire detection processing according to the embodiment of the present invention; FIG. 5 is a diagram showing an example of misfire detection according to the embodiment of the present invention;

Embodiments of the present invention will be described below.
FIG. 1 shows the configuration of an engine testing system according to this embodiment.
As shown, the engine test system includes a dynamometer 1, a torque sensor 2, a tachometer 3, a shaft 4, an intermediate bearing 5, and a measurement control device 6.
The rotating shaft of the dynamometer 1 is connected to one end of the shaft 4 through the torque sensor 2 and the other end of the shaft 4 is connected to the output shaft of the engine 7 . A torque sensor 2 detects torque acting between the shaft 4 and the rotating shaft of the dynamometer 1 , and a tachometer 3 detects the rotating speed of the rotating shaft of the dynamometer 1 . The intermediate bearing 5 supports the shaft 4 so that the output shaft of the engine 7 is not subjected to a non-rotational load.

The measurement control device 6 controls the dynamometer 1 and the engine 7 to execute a predetermined measurement sequence to measure various states of the engine 7 .
Here, the engine 7 to be measured in this embodiment is an internal combustion engine or a reciprocating engine 7. A catalyst 72 for purifying exhaust gas discharged through an exhaust manifold 71 connected to an exhaust port, the engine 7 and a throttle 73 for adjusting the amount of intake air flowing into.

Also, FIG. 2 shows the configuration of the control/measurement system of the engine test system. The engine 7 includes an intake air amount sensor 701 that detects the flow rate flowing through the intake pipe of the engine 7, an intake pipe pressure sensor 702 that detects the pressure in the intake pipe, a catalyst temperature sensor 703 that detects the temperature of the catalyst 72, and a cylinder of the engine 7. In-cylinder pressure sensor 704 for detecting pressure in (cylinder), Crank angle sensor 705 for detecting rotation angle and speed of crankshaft of engine 7, Throttle opening sensor 706 for detecting opening of throttle 73, Engine 7 A throttle actuator 707 for driving the throttle 73 of the engine 7 and a variable valve mechanism 708 for adjusting the valve timings of the intake and exhaust valves of the engine 7 are provided.

Further, as shown in FIG. 2 , the measurement control device 6 includes a measurement processing section 61 , a misfire detection section 62 , a constant speed operation control section 63 and a measurement sequence control section 64 .
The measurement sequence control unit 64 of the measurement control device 6 controls any one of A valve timings different from each other for the intake valves of the engine 7, any one of B valve timings different from each other for the exhaust valves of the engine 7, and an upper limit Basic measurement of each of n (n=A×B×C) combinations obtained as mutually different combinations with any one of C mutually different rotational speeds of the engine 7 from the rotational speed to the idling rotational speed As a condition, for each basic condition, while changing the throttle opening from the maximum opening to the minimum opening while making the state of the engine 7 match the basic condition, the intake air amount sensor 701 is supplied to the measurement processing unit 61. , and the pressure in the intake pipe detected by the intake pipe pressure sensor 702 are measured.

FIG. 3 shows the procedure of the measurement sequence control process performed by the measurement sequence control section 64. As shown in FIG.
As shown, in the measurement sequence control process, first, i is initialized to 1 (step 302).
Then, by controlling the variable valve mechanism, the valve timing of the intake valve of the engine 7 is set to the valve timing of the intake valve of the i-th basic measurement condition, and the valve timing of the exhaust valve of the engine 7 is set to the valve timing of the i-th basic measurement condition. set the valve timing of the exhaust valve, set the rotation speed of the i-th basic measurement condition in the constant speed operation control unit 63 as the target rotation speed, and control the constant speed operation of the dynamometer 1 at the set target rotation speed. is started (step 304).

Here, when the constant-speed operation control unit 63 starts controlling the constant-speed operation, the rotational speed of the rotating shaft of the dynamometer 1 detected by the tachometer 3 or the rotational speed of the crankshaft detected by the crank angle sensor 705 is detected. With reference to the rotation speed of the engine 7, the torque generated by the dynamometer 1 is controlled so that the engine 7 rotates at the set target rotation speed.

Then, the target throttle opening tp is set to the maximum opening (step 306), and the misfire detection process of the misfire detector 62 is started (step 308). Here, the misfire detection process performed by the misfire detection unit 62 is a process for detecting a misfire of the engine 7, and the details thereof will be described later.

Then, the throttle actuator 707 is caused to start transitioning the throttle opening of the engine 7 to the target throttle opening tp (step 310), and the measurement processing section 61 is caused to start measurement processing (step 312).

The measurement processing unit 61, which has started the measurement processing, detects that the throttle opening of the engine 7 detected by the throttle opening sensor 706 has stabilized at the target throttle opening tp, and that the rotation speed of the dynamometer 1 has stabilized at the target rotation speed. Then, the flow rate in the intake pipe detected by the intake air amount sensor 701, the pressure in the intake pipe detected by the intake pipe pressure sensor 702, the torque detected by the torque sensor 2, and other sensors. The detected value is measured and stored in association with the basic measurement conditions at that point in time, the target throttle opening tp, etc. When the measurement is completed, the measurement process is terminated.

Next, in the measurement sequence control process, if the measurement processing unit 61 is caused to start the measurement processing (step 312), the misfire detection unit 62 detects a misfire (step 314), and the measurement processing by the measurement processing unit 61 (step 316).

Then, if the misfire is not detected by the misfire detector 62 (step 314) and the measurement process ends (step 316), it is checked whether the target throttle opening tp is the minimum opening (step 318). ), if it is not the minimum opening, the target throttle opening tp is decreased by a predetermined unit opening Δtp (step 324), and the processing from step 310 is returned to.

On the other hand, if the target throttle opening tp is the minimum opening (step 318), the misfire detection process of the misfire detector 62 is terminated (step 320).
Then, it is checked whether i has reached n, which is the total number of basic measurement conditions (step 322). If it has reached n, the measurement sequence control process is terminated. After incrementing (step 326), the processing from step 304 is returned to.

On the other hand, when misfire is detected by the misfire detection unit 62 after the measurement processing unit 61 starts the measurement processing (step 312) and before the measurement processing by the measurement processing unit 61 ends (step 316). (step 314), the target throttle opening tp+Δtp is stored as the lower limit combustion opening together with the i-th basic measurement condition (step 328), and the throttle actuator 707 is set to the throttle opening of the engine 7 above the unit opening Δtp. is increased by a predetermined amount (step 330). For example, at step 330, the throttle actuator 707 is caused to start transitioning the throttle opening of the engine 7 to the maximum opening.

Here, the reason why the throttle opening is increased in step 330 is to eliminate the misfire state and avoid the occurrence of damage to the engine 7 and the like.
Next, the misfire detection processing of the misfire detection unit 62 is terminated (step 320), it is checked whether i has reached n (step 322), and if it has reached n, the measurement sequence control processing is terminated and n If not, i is incremented by 1 (step 326) and the process from step 304 is returned to.

The measurement sequence control processing performed by the measurement sequence control section 64 has been described above.
Here, the lower limit of combustion opening for each basic measurement condition memorized by the measurement sequence control process can be used in other measurements of the engine 7 to be performed later, or in an automobile equipped with the same type of engine 7 as the engine rotation speed at that time. It can be used for applications such as limiting the lower limit of the throttle opening to the lower limit of the combustion opening corresponding to the basic measurement conditions that match the speed and valve timing.

Next, the details of the misfire detection performed by the misfire detector 62 will be described.
FIG. 4 shows the configuration of the misfire detector 62. As shown in FIG.
As illustrated, the misfire detection section 62 includes a combustion analysis section 621 and a misfire detection processing section 622 .
The combustion analysis unit 621 calculates the combustion fluctuation rate, which is a value obtained by dividing the standard deviation of the indicated mean effective pressure (IMEP) by the average of the indicated mean effective pressure. The indicated average effective pressure is a finger pressure that records the pressure change in the cylinder in one cycle, which is obtained from the pressure in the cylinder of the engine 7 detected by the in-cylinder pressure sensor 704 and the rotational angle of the crankshaft detected by the crank angle sensor 705. It is obtained by dividing the area within the curve of the diagram (PV diagram) by the stroke volume of the cylinder.

The combustion variation rate is preferably calculated for each cylinder by providing an in-cylinder pressure sensor 704 for each cylinder of the engine 7. , the combustion variation rate may be calculated only for that cylinder.

The indicated mean effective pressure is calculated for each cycle, and the mean, standard deviation, and combustion fluctuation rate of the indicated mean effective pressure are calculated from the indicated mean effective pressure obtained for a predetermined number of past cycles.
The combustion fluctuation rate calculated in this manner represents the fluctuation rate of the amount of work per cycle of the cylinders of the engine 7 .
However, the combustion analysis unit 621 may use the indicated work instead of the indicated mean effective pressure, and calculate the value obtained by dividing the standard deviation of the indicated work by the average of the indicated work as the combustion fluctuation rate. The indicated work is obtained as the area within the curve of the finger pressure diagram (PV diagram) that records the pressure change in the cylinder in one cycle.

The combustion fluctuation rate calculated using the indicated work in this manner also represents the fluctuation rate of the amount of work per cylinder of the engine 7 per cycle.
Next, the misfire detection processing of the misfire detection unit 62 described above is performed by the misfire detection processing unit 622 .
FIG. 5 shows the procedure of this misfire detection process.
As shown in the figure, in the misfire detection process, the temperature of the catalyst 72 detected by the catalyst temperature sensor 703 at the end of the previous measurement process performed by the measurement processing unit 61 is used as the reference temperature. If the temperature rises from the reference temperature by a threshold value Tht (Tht is, for example, 2° C.) (step 502), a misfire is detected and the measurement sequence controller 64 is notified of the occurrence of the misfire (step 508).

However, step 502 does not detect an increase in the temperature of the catalyst 72 from the reference temperature by the threshold value Tht or more until the first measurement process after the change in the basic measurement conditions is completed.
Further, in step 502, the temperature of the catalyst 72 detected during the period during which the throttle opening is stable at the target throttle opening tp at that time during the execution of the previous measurement processing performed by the measurement processing unit 61 is used as a reference temperature. may be used as

Here, according to steps 502 and 508 and the measurement sequence control process described above, for each basic measurement condition, as shown in FIG. When the temperature of the catalyst 72 rises by a threshold Tht or more from the temperature when the throttle opening of the engine 7 was set to the target throttle opening tp at the time of the previous measurement processing in the process of performing the measurement processing by A misfire is detected, and the throttle opening tp_min at the time of the last measurement process completed before the misfire is detected is stored as the lower limit combustion opening along with the basic measurement conditions at that time.

Here, the throttle opening degree at each time point is smaller than the target throttle opening degree tp at the time of the previous measurement processing, so if the engine 7 is in normal combustion, the catalyst temperature will be lower than when the reference temperature was detected. On the other hand, when a misfire occurs in the engine 7, the amount of unburned gas postburned in the catalyst 72 increases, so the temperature of the catalyst 72 rises. Therefore, by detecting the occurrence of misfire from the temperature rise of the catalyst 72, the occurrence of misfire can be detected more directly and accurately.

In the misfire detection process, if the combustion variation rate calculated by the combustion analysis unit 621 exceeds the threshold value Thv (Thv is, for example, 5%) (step 504), misfire is detected and the measurement sequence control unit 64 is notified of the occurrence of a misfire (step 508).

When calculating the combustion fluctuation rate for each cylinder of the engine 7 as described above, in steps 504 and 508, if the combustion fluctuation rate of at least one cylinder is equal to or greater than the threshold value Thv, A misfire is detected and the measurement sequence control section 64 is notified of the occurrence of the misfire.

Here, according to steps 504 and 508 and the measurement sequence control process described above, for each basic measurement condition, as shown in FIG. In the process of performing the measurement processing by, when the combustion variation rate exceeds the threshold Thv, a misfire is detected, and the throttle opening tp_min at the time of the last measurement processing completed before misfire detection is used as the lower limit combustion opening. It is stored together with the basic measurement conditions at that time.

Here, when misfires occur or do not occur in each cycle of the engine 7, the combustion fluctuation rate increases. Misfire can be detected well.

In the misfire detection process, if the torque detected by the torque sensor 2 becomes negative (step 506), misfire is detected and the measurement sequence controller 64 is notified of the occurrence of misfire (step 508).

Here, the torque detected by the torque sensor 2 is positive when the direction of the torque is the direction in which the dynamometer 1 applies a force that prevents the engine 7 from rotating in the forward rotation direction, and the dynamometer It is negative when 1 is in the direction of applying a force to the engine 7 to rotate the engine 7 in the forward rotation direction.

Further, the reason why the torque detected by the torque sensor 2 becomes negative due to the torque control of the dynamometer 1 by the constant speed operation control unit 63 to keep the rotation speed of the engine 7 constant is that all the cylinders of the engine 7 misfire. This is the case where the engine 7 is a load on the dynamometer 1 without generating any torque. Therefore, a misfire of the engine 7 can be detected by detecting negative torque in this way.

The embodiments of the present invention have been described above.

DESCRIPTION OF SYMBOLS 1... Dynamometer, 2... Torque sensor, 3... Tachometer, 4... Shaft, 5... Intermediate bearing, 6... Measurement control device, 7... Engine, 61... Measurement processing unit, 62... Misfire detection unit, 63... Constant speed Operation control unit 64 Measurement sequence control unit 71 Exhaust manifold 72 Catalyst 73 Throttle 621 Combustion analysis unit 622 Misfire detection processing unit 701 Intake air amount sensor 702 Intake pipe pressure sensor , 703... catalyst temperature sensor, 704... in-cylinder pressure sensor, 705... crank angle sensor, 706... throttle opening sensor, 707... throttle actuator, 708... variable valve mechanism.

Claims (7)

An engine test system for testing an engine, comprising:
a dynamometer that applies torque to the output shaft of the engine;
a catalyst temperature sensor that detects the temperature of a catalyst that purifies exhaust gas from the engine;
test control means for executing a measurement process for measuring the state of the engine at each stage while decreasing the throttle opening of the engine in stages;
The temperature of the catalyst detected by the catalyst temperature sensor has increased by a predetermined temperature or more from the temperature of the catalyst detected by the catalyst temperature sensor when the throttle opening was at the opening of the previous stage. and misfire detection means for detecting misfires of said engine. An engine test system for testing an engine, comprising:
a dynamometer that applies torque to the output shaft of the engine;
an in-cylinder pressure sensor that detects an in-cylinder pressure of a cylinder of the engine;
a fluctuation rate calculation means for calculating a fluctuation rate of the amount of work per cycle of the cylinder of the engine from the in-cylinder pressure detected by the in-cylinder pressure sensor;
test control means for executing a measurement process for measuring the state of the engine at each stage while decreasing the throttle opening of the engine in stages;
and misfire detection means for detecting a misfire of the engine when the fluctuation rate calculated by the fluctuation rate calculation means exceeds a predetermined threshold value. The engine test system of claim 2, wherein
The fluctuation rate calculation means divides the standard deviation of the indicated mean effective pressure obtained from the in-cylinder pressure detected by the in-cylinder pressure sensor by the mean of the indicated mean effective pressure, and calculates the work per cycle of the cylinder of the engine. An engine test system characterized in that it is calculated as a rate of change in quantity. 4. The engine test system according to claim 2 or 3,
a catalyst temperature sensor that detects the temperature of a catalyst that purifies exhaust gas from the engine;
The misfire detection means detects the temperature of the catalyst detected by the catalyst temperature sensor from the temperature of the catalyst detected by the catalyst temperature sensor when the throttle opening is at the opening of the previous stage. and detecting misfires in the engine even when the temperature rises above . The engine test system of claim 1, 2, 3 or 4, comprising:
A torque sensor that detects torque acting between the engine and the dynamometer,
The test control means controls the dynamometer so that the rotation speed of the engine becomes a predetermined rotation speed,
The misfire detection means also detects a misfire of the engine when the direction of the torque detected by the torque sensor becomes torque acting to rotate the output shaft of the engine in the forward rotation direction of the engine. An engine test system characterized by: The engine test system of claim 1, 2, 3, 4 or 5, wherein
The test control means is characterized in that, when the misfire detection means detects a misfire, the test control means stops the stepwise reduction of the throttle opening of the engine and increases the throttle opening of each engine. engine test system. The engine test system of claim 1, 2, 3, 4, 5 or 6,
Combustion lower limit throttle opening detection means for detecting a throttle opening at a stage immediately before misfire is detected by the misfire detection means as a combustion lower limit throttle opening, which is the minimum opening of the throttle at which misfire does not occur. and engine test system.

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