JP4102576B2 - Compression top dead center detector for the engine under test - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an external drive means that is connected to a crankshaft of a test target engine and forcibly rotates the crankshaft, a pressure detection means that detects a pressure in a cylinder of the test target engine, In a state where the crankshaft is rotated by the external drive unit and a rotation phase detection unit that detects a rotation phase, the compression of the engine is increased based on detection information of the pressure detection unit and the rotation phase detection unit. The present invention relates to a compression top dead center detecting device for a test target engine provided with a calculation means for obtaining a dead center.
[0002]
[Prior art]
Recently, when the engine is tested, the fuel is not supplied and actually burned, but the crankshaft is driven to rotate by an external driving means, thereby various kinds of timing such as opening and closing timings of intake valves and exhaust valves. Although a cold test for performing an engine test may be performed, the compression top dead center detection device for the engine under test having the above configuration is a reference for detecting the opening / closing timing of the intake valve and the exhaust valve in such a cold test. As the rotational phase, the compression top dead center of the engine is obtained.
[0003]
By the way, in the cold test as described above, for example, an engine test is performed by rotating the crankshaft by an external drive means even for an engine in the middle of assembly where a fuel injection nozzle, a spark plug or the like is not yet mounted. Therefore, even if it is necessary to carry out a rework work by the engine test, it is possible to reduce the cost by reducing the number of rework steps.
[0004]
As a compression top dead center detection device for such a test target engine, there has conventionally been a configuration shown in, for example, Japanese Patent Application Laid-Open No. 2000-82238. That is, a pressure sensor is installed as a pressure detection means for detecting the pressure in the cylinder using an attachment hole such as a fuel injection nozzle or a spark plug, and the crankshaft of the test target engine is driven to rotate by an external drive means such as a motor. By detecting the rotation phase of the crankshaft by a rotation sensor serving as a rotation phase detecting means that detects the crankshaft, the crankshaft corresponding to the maximum pressure value by the pressure sensor during one cycle of the engine is detected. In this configuration, the highest pressure point phase is detected, and the compression top dead center is detected based on the highest pressure point phase. Specifically, the crankshaft is driven to rotate at a plurality of rotational speeds from a low speed to a high speed by an external drive means, and a maximum pressure point phase for each rotational speed is obtained, and the maximum pressure point phase and the rotational speed are determined. The relationship is numerically analyzed to obtain an empirical formula having a predetermined asymptote when the rotational speed is infinite, and a phase corresponding to the asymptote is detected as a compression top dead center phase. One cycle of the engine corresponds to a cycle in which each of the intake stroke, the compression stroke, the expansion stroke, and the exhaust stroke is completed. The crankshaft is driven in a normal rotation direction, that is, a normal rotation direction in which the engine rotates by combustion.
[0005]
In addition, when the crankshaft is rotated, when the piston is at the top dead center in the compression stroke, that is, when the piston is at the compression top dead center, the pressure in the cylinder is considered to be the maximum value. In an actual engine, the phase in which the pressure in the cylinder becomes maximum and the phase corresponding to the compression top dead center are slightly shifted due to factors such as compression leakage and heat dissipation. In order to reduce such a shift, In the prior art, the phase at which the pressure in the cylinder becomes maximum, that is, the highest pressure point phase is corrected to obtain the compression top dead center phase.
[0006]
[Problems to be solved by the invention]
However, in the above prior art, when the maximum pressure point phase for each of a plurality of rotation speeds is obtained and the relationship between the maximum pressure point phase and the rotation speed is numerically analyzed to make the rotation speed infinite, the predetermined asymptotics are obtained. Since the configuration is such that an empirical formula having a line is obtained by calculation, there are the following disadvantages.
[0007]
That is, the empirical formula obtained by numerical analysis of the relationship between the maximum pressure point phase and the rotational speed as described above is an approximate formula for expressing the phase shift due to various factors in the engine as described above, Even if the phase corresponding to the asymptote is detected as the phase corresponding to the compression top dead center, the phase is not necessarily an accurate compression top dead center phase and may include an error.
In addition, in order to accurately obtain the compression top dead center phase with this configuration, it is necessary to increase the number of detection data for the phase at which the pressure in the cylinder is maximum, but the detection data is increased in this way. In order to achieve this, the process for obtaining the maximum pressure point phase by varying the rotation speed of the crankshaft must be performed many times, which requires a long time for the detection process. It was difficult to apply in case of sequentially inspecting.
[0008]
The present invention has been made paying attention to such a point, and an object of the present invention is to improve the compression of a test target engine that can detect an accurate compression top dead center without increasing the time required for detection processing. It is in providing a dead point detection device.
[0009]
[Means for Solving the Problems]
The compression top dead center detecting device for a test target engine according to claim 1 is connected to a crankshaft of the test target engine, forcibly rotates the crankshaft, and in the cylinder of the test target engine. Pressure detecting means for detecting the pressure of the crankshaft, rotational phase detecting means for detecting the rotational phase of the crankshaft, and in the state where the crankshaft is rotated by the external drive means, the pressure detecting means and the rotational phase Calculation means for obtaining a compression top dead center of the engine based on detection information of the detection means,
The external drive means is configured to be switchable between a state in which the crankshaft is rotated in a normal rotation direction and a state in which the crankshaft is rotated in a reverse rotation direction, and the calculation means is configured to switch the crankshaft by the external drive means. The crank when the pressure in the cylinder reaches the maximum value in one cycle of the engine under test based on the pressure detection value detected by the pressure detection means in a state of rotating in the normal rotation direction. The pressure detected by the pressure detecting means in a state where the rotational phase of the shaft is obtained as a first precompression top dead center and the crankshaft is rotated in the reverse rotation direction by the external driving means. Based on the detected value, a rotation phase of the crankshaft when the pressure in the cylinder reaches a maximum value in the one cycle is obtained as a second precompression top dead center, and The rotation phase of the crankshaft positioned at the center between one preliminary compression top dead center and the second preliminary compression top dead center is determined as the compression top dead center of the engine. To do.
The one cycle corresponds to a cycle in which the engine to be tested performs each of the intake stroke, the compression stroke, the expansion stroke, and the exhaust stroke as the crankshaft rotates.
[0010]
That is, in a state where the crankshaft is rotated in the normal rotation direction by the external drive means, the rotation phase of the crankshaft when the pressure in the cylinder reaches the maximum value in the one cycle is defined as the first preliminary compression top dead center. Asking. Further, when the crankshaft is rotated in the reverse rotation direction by the external drive means, the rotation phase of the crankshaft when the pressure in the cylinder reaches the maximum value in the one cycle is set as the second preliminary compression top dead center. Ask. Then, the rotational phase of the crankshaft located at the center between the first preliminary compression top dead center and the second preliminary compression top dead center is obtained as the compression top dead center of the engine.
[0011]
In other words, when the crankshaft rotation phase is calculated when the crankshaft is rotated in the normal rotation direction and the pressure in the cylinder reaches the maximum value, as described above, compression leakage, heat dissipation, etc. Depending on the factor, the rotational phase at which the pressure in the cylinder becomes maximum and the rotational phase corresponding to the compression top dead center are slightly shifted, so the first preliminary compression top dead center is shifted from the compression top dead center. It will be. Specifically, the first preliminary compression top dead center is a phase on the upper side in the rotational direction than the compression top dead center.
Similarly, when the detection is performed while the crankshaft is rotated in the reverse rotation direction, the second preliminary compression top dead center is shifted from the compression top dead center. The top dead center is a phase on the upper side of the rotation direction than the compression top dead center. In this case, however, the rotation direction is opposite, so the second preliminary compression top dead center is considered based on the normal rotation direction. The phase is on the lower side in the rotational direction than the compression top dead center.
[0012]
That is, when the normal rotational direction is considered as a reference, the first preliminary compression top dead center is located on the upper side in the rotational direction than the compression top dead center, and the second preliminary compression top dead center is greater than the compression top dead center. Is also located on the lower side in the rotational direction. In addition, since it is considered that the amount of displacement with respect to the compression top dead center is substantially the same, the rotational phase of the crankshaft located at the center between the first preliminary compression top dead center and the second preliminary compression top dead center is determined. The exact compression top dead center is obtained by obtaining the compression top dead center of the engine. That is, the phase difference between the phase at which the pressure in the cylinder of the engine becomes maximum and the phase corresponding to the compression top dead center is opposite in the normal rotation direction and the reverse rotation direction. By obtaining the center between the top dead center and the second preliminary compression top dead center, it is possible to cancel the misalignment between them and obtain the most accurate compression top dead center as much as possible.
[0013]
Therefore, at least the first preliminary compression top dead center and the second preliminary compression top dead center are detected at least once compared to a configuration in which an approximate expression is obtained based on numerical analysis of detection data as in the prior art. It is possible to obtain the compression top dead center, and it is possible to accurately detect the compression top dead center without increasing the time required for the detection process. I was able to provide.
[0014]
The compression top dead center detection apparatus for a test target engine according to claim 2 is the compression top dead center detection apparatus for a test target engine according to claim 1, wherein the calculation means includes the first preliminary compression top dead center. And when the second preliminary compression top dead center is obtained, the pressure detection value detected by the pressure detection means is sampled every set period, and the sampled sampling value The moving average value for each set number is obtained, the rotation phase of the crankshaft when the moving average value reaches the maximum value in the one cycle, and the pressure in the cylinder reaches the maximum value in the one cycle. It is comprised so that it may obtain | require as a rotational phase of the said crankshaft.
[0015]
That is, in order to obtain the rotation phase of the crankshaft when the pressure reaches the maximum value, the moving average value is obtained for each set number of sampling values for the pressure detection values sampled for each set period. For example, even if the pressure detection value detected by the pressure detection means is a value that temporarily changes greatly due to disturbance, the detection value is obtained by obtaining the moving average value. Therefore, it is possible to suppress the occurrence of an error due to this, without using a value that temporarily changes greatly due to a disturbance, and suitable for carrying out the present invention. Can be obtained.
[0016]
The compression top dead center detection device for a test target engine according to claim 3 is the compression top dead center detection device for a test target engine according to claim 1 or 2, wherein the pressure detection means is the detection target. The cylinder is configured to be connected to the cylinder via a pressure reducing buffer.
[0017]
That is, in order to detect the pressure in the cylinder of the engine to be tested, it is necessary to connect the pressure detecting means to the cylinder of the engine. At this time, the pressure detecting means is connected via a buffer for reducing pressure. ing. That is, when the crankshaft is forcibly rotated by the external drive means, the inside of the cylinder temporarily becomes a high pressure due to the compression action of the piston, but since it is connected via a buffering part for decompression, The high pressure inside the cylinder is not transmitted as it is to the pressure detecting means through the connecting portion by the pressure reducing buffer. Even if the pressure is not an absolute value but a reduced value, it is possible to detect the rotation phase of the crankshaft when the pressure in the cylinder reaches the maximum value in one cycle.
[0018]
Therefore, it is possible to avoid the disadvantage that the connection portion between the pressure detection means and the cylinder of the engine is damaged or disconnected due to the high pressure as described above, which is suitable for implementing the first aspect. Can be obtained.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an engine test apparatus including a compression top dead center detection apparatus for a test target engine according to the present invention will be described with reference to the drawings.
As shown in FIG. 1, this engine test apparatus is connected to a crankshaft 4 of a test target engine 1 attached to a pallet P, and has an external drive means including an electric motor 2 for forcibly rotating the crankshaft 4. 3. The encoder 5 as a rotation phase detecting means for detecting the rotation phase of the crankshaft 4 by detecting the rotation of the crankshaft 4; the rotation speed of the electric motor 2 is controlled; The control unit H is configured to test whether or not the timing of opening / closing operation of the intake valve and the exhaust valve is appropriate based on detection information of various sensors S and the encoder 5 as described later.
[0020]
The encoder 5 outputs a reference signal of one pulse every time the crankshaft 4 makes one rotation to be a reference for the rotation phase, and outputs a pulse one by one every time the crankshaft 4 rotates by a predetermined unit angle. Is configured to output. This timing pulse is output at 3600 pulses per revolution.
[0021]
In this engine test apparatus, the engine 1 to be tested is transported to a predetermined test setting position by a transport device such as a conveyor while being mounted on the pallet P, and rotation of the electric motor 2 in the external drive means 3 is performed by an operator. The shaft 2a is connected to the crankshaft 4 via a connecting tool CP. When the test target engine 1 is thus transported to the test setting position, a test given in advance with a barcode is performed. The identification information ID for management of the target engine is read by the barcode sensor 30, and the identification information ID is input to the control unit.
The external drive means 3 is configured to be switchable between a state in which the crankshaft 4 is rotated in a normal rotation direction and a state in which the crankshaft 4 is rotated in a reverse rotation direction, and can rotate the crankshaft 4 at different rotational speeds. It has become.
[0022]
Then, with the external drive means 3 connected in this manner, the control unit H controls the rotational speed of the electric motor 2 to be the rotational speed for testing based on the operation command, and the electric motor 2 By forcibly rotating the crankshaft 4 by the rotational operation, the piston 7 is moved up and down and the intake valve 9 and the exhaust valve 10 are opened and closed as shown in FIG. Then, an expansion stroke and an exhaust stroke are sequentially repeated, and a cold test is performed in which various engine tests such as opening and closing timings of the intake valve 9 and the exhaust valve 10 are performed without actually burning.
[0023]
Further, in this engine test apparatus, when performing the above-described cold test, the compression top dead center of the test target engine becomes a reference for various measurements. The compression top dead center TDC of the reference cylinder 6a is obtained, and the opening / closing operation timing of the intake valve 9 and the exhaust valve 10 mounted on each cylinder 6 is measured using the compression top dead center of the reference cylinder 6a as a reference point. The pass / fail of the test target engine is determined based on whether the opening / closing operation timing is within an appropriate range.
[0024]
As shown in FIG. 2, the test target engine 1 is a four-cylinder four-cycle diesel engine, and includes a crankshaft 4 connected to a piston 7 of each cylinder 6 via a connecting rod 8, an intake valve 9, and A camshaft 11 having a cam for opening and closing the exhaust valve 10 is provided, and the crankshaft 4 and the camshaft 11 are connected by a gear-type interlocking mechanism 12. This gear-type interlocking mechanism 12 rotates a crankshaft gear 12a provided on the crankshaft 4 and a camshaft gear 12c provided on the camshaft 11 in an interlocking manner by meshing the gears via a relay gear 12b. The number of gear teeth is set so that when the crankshaft 4 rotates twice, the camshaft 11 rotates once in the same direction.
As the crankshaft 4 is rotated, the piston 7 of each cylinder 6 is moved up and down, and the camshaft 11 is rotated to open and close the intake valve 9 and the exhaust valve 10. The fuel injection nozzle that injects fuel into the cylinder is not installed at this test stage. And the structure which connects the pressure sensor 14 as a pressure detection means for detecting the pressure in the cylinder which is one of the sensors S using the mounting hole 13 for mounting | wearing with this fuel injection nozzle, It has become.
[0025]
The connection configuration of the pressure sensor 14 will be described. As shown in FIG. 3, the length of the reference cylinder 6a is about 800 to 900 mm with respect to the mounting hole 13 using a connection jig 15. A length of the hydraulic hose 16 is connected, and the pressure sensor 14 is connected to the tip of the hydraulic hose 16. The pressure sensor 14 is connected through the hydraulic hose 16 in this way because the pressure in the cylinder 6a is high, so that the connection location is not accidentally disconnected or damaged during inspection work. The hydraulic hose 16 which is excellent and flexible and easy to work is used to exhibit a buffer function so as to reduce the high pressure in the cylinder. That is, the hydraulic hose 16 functions as a buffer for reducing pressure. The pressure sensor 14 is configured to detect the pressure in the reference cylinder 6a connected through the hydraulic hose 16 as it is, and is configured to be used for processing for detecting the compression top dead center of the reference cylinder 6a.
For the other three cylinders 6 other than the reference cylinder 6a, the mounting hole 13 is closed by a closing member.
[0026]
Further, a hydraulic pressure having a length of about 800 to 900 mm using a connecting jig 19 with respect to an intake port 18 of an intake manifold 17 for supplying air into each cylinder 6 through each intake valve 9. A hose 20 is connected, and a pressure sensor 21 which is one of sensors for detecting the internal pressure of the intake manifold 17 is connected to the tip of the hydraulic hose 20. The pressure sensor 21 is used for processing for inspecting the opening / closing timing of the intake valve 9.
[0027]
Next, a processing procedure by the engine test apparatus will be described.
As shown in FIG. 4, the test target engine 1 is transported to the test setting position, and the external drive means 3 is connected to the crankshaft 4 (step 1). At this time, the identification information ID for management of the test target engine 1 is read, and the identification information ID is input to the control unit H (step 2). When the connection work of the external drive means 3 is completed and the worker commands the start of detection, the control unit H executes a detection process of the compression top dead center TDC (hereinafter referred to as a TDC detection process) (step 3). ). When the compression top dead center TDC detection process ends, the valve timing is detected based on the compression top dead center TDC. That is, a process for detecting the opening timing of the intake valve 9, a process for detecting the closing timing of the intake valve 9, and a process for detecting the opening timing of the exhaust valve 10 are executed. The process which determines the pass / fail of the test object engine 1 by whether it is an appropriate state is performed (steps 4-7).
[0028]
When the control unit H executes the TDC detection process, the control unit H sets the pressure detection value detected by the pressure sensor 14 in a state where the crankshaft 4 is rotated in the normal rotation direction by the external driving unit 3. Based on this, the rotational phase of the crankshaft 4 when the pressure in the cylinder reaches the maximum value in one cycle of the reference cylinder 6a is obtained as the first preliminary compression top dead center, and the external drive means 3 In the state in which 4 is rotated in the reverse rotation direction, the rotation phase of the crankshaft 4 when the pressure in the cylinder reaches the maximum value in one cycle is determined based on the pressure detection value detected by the pressure sensor 14. Obtained as the second preliminary compression top dead center, and further, the rotational phase of the crankshaft 4 positioned at the center between the first preliminary compression top dead center and the second preliminary compression top dead center is determined as the compression top dead center of the engine. As you ask It has been made. Here, the one cycle corresponds to a cycle in which the test target engine 1 performs each of the intake stroke, the compression stroke, the expansion stroke, and the exhaust stroke as the crankshaft 4 rotates. That is, the crankshaft 4 rotates twice during this one cycle.
[0029]
In addition, when the first preliminary compression top dead center is obtained and when the second preliminary compression top dead center is obtained, the pressure detection value detected by the pressure sensor 14 is sampled every set period. At the same time, a moving average value is obtained for each set number of sampled sampling values, and the rotational phase of the crankshaft 4 when the moving average value reaches the maximum value in one cycle is determined in the cylinder. The rotation phase of the crankshaft 4 when the pressure reaches the maximum value is obtained.
[0030]
Next, the TDC detection processing by the control unit H will be described based on the flowchart shown in FIG.
Rotational speed at which the crankshaft 4 is rotated in the normal rotation direction (hereinafter referred to as the forward rotation direction) by the external drive means 3 and the rotation speed of the crankshaft 4 is 60 rotations per minute based on the detection information of the encoder 5 The speed is controlled so as to be (60 rpm) (step 31). In a state of rotating in the forward direction at such a set speed, the pressure detection value in the pressure sensor 14 connected to the cylinder of the reference cylinder 6a is sampled every set unit time, and the sampled value is a predetermined number. The process of obtaining the moving average value (51 pieces) is sequentially executed (steps 32 and 33). This moving average value is obtained every time the encoder 5 outputs a timing pulse. Further, the control unit H continuously executes the process of integrating the timing pulses output from the encoder 5, and when the reference signal output every rotation is input, the integrated value of the timing pulses at that time Is reset to zero, and such processing is repeatedly executed. Then, a process of obtaining the rotational phase of the crankshaft 4 when the moving average value becomes maximum in one cycle as the first preliminary compression top dead center TDC (Y1) is executed (step 34). Thus, steps 31 to 34 are repeatedly executed until the first preliminary compression top dead center TDC (Y1) is obtained.
[0031]
When the first pre-compression top dead center TDC (Y1) is obtained, the crankshaft 4 is then rotated in the reverse direction by the external driving means 3 so that the rotational speed (60 rpm) is 60 revolutions per minute. In the rotation state in the reverse rotation direction, the pressure detection value is sampled and the sampled value is moved by a predetermined number (51) in the same manner as the processing in the normal rotation state. The processing for obtaining the value is sequentially executed (steps 35, 36, 37, 38), and the rotational phase of the crankshaft 4 when the moving average value becomes maximum in one cycle is determined as the second preliminary compression top dead center TDC ( Y2) is obtained (step 39). Then, Steps 36 to 39 are repeatedly executed until the second preliminary compression top dead center TDC (Y2) is obtained.
When the second preliminary compression top dead center TDC (Y2) is obtained, the rotation operation of the electric motor 2 is stopped, and the second preliminary compression top dead center is positioned at the center between the first preliminary compression top dead center and the second preliminary compression top dead center. The rotational phase of the crankshaft 4 is determined as the compression top dead center of the engine (steps 40, 41, 42).
[0032]
In other words, FIG. 6 shows the output value of the encoder 5 and the pressure detection value (moving average value) in a state where the rotation phases correspond to each other. Among them, FIG. 6 (a) shows a change in the rotation state in the forward rotation direction, and FIG. 6 (b) shows a change in the rotation state in the reverse rotation direction.
In a 4-cycle engine, the piston 7 reciprocates twice during the intake stroke, compression stroke, expansion stroke, and exhaust stroke, so there are two top dead centers of the compression stroke and the exhaust stroke. In the exhaust stroke, the pressure in the cylinder does not become high because the exhaust valve 10 is open, and the pressure in the cylinder is maximized only at the top dead center (compression top dead center) in the compression stroke. Therefore, as shown in the figure, there is a point (compression top dead center) at which the pressure in the cylinder becomes maximum during one rotation of the crankshaft 4.
[0033]
Therefore, angle information (A) between the point at which the pressure in the forward rotation state becomes maximum in one cycle (first preliminary compression top dead center) and the reference signal on the upper side in the rotational direction than that, The angle information (B) between the point at which the pressure in the reverse rotation state becomes the maximum in one cycle (second preliminary compression top dead center) and the reference signal on the lower side in the rotational direction is represented by the encoder 5. As shown in FIG. 6 (c), it corresponds to an angle that is an average value of the angle information (A) and the angle information (B) with reference to the normal rotation state. The phase, that is, the rotational phase of the crankshaft 4 positioned at the center between the first preliminary compression top dead center and the second preliminary compression top dead center is obtained as the true compression top dead center TDC. The compression top dead center TDC obtained in this way is stored in correspondence with the rotation phase obtained from the detection signal of the encoder 5. Thereafter, the operation timing of the intake valve 9 and the exhaust valve 10 is detected based on the compression top dead center thus obtained.
Therefore, a calculation means for obtaining the compression top dead center of the engine using the control unit H is configured.
[0034]
Next, among the plurality of valve timing detection processes, the opening timing detection process of the intake valve 9 will be described as an example, and the description of the other valve operation timing detection processes will be omitted.
The intake valve 9 is opened when the crankshaft 4 is rotated in the forward direction by the external drive means 3 and the intake manifold 17 is in the intake manifold 17 in a state where the speed is controlled to 30 rpm (30 rpm) per minute. The detection value of the pressure sensor 21 connected to the port 18 is sampled at every set cycle in the same manner as in the TDC detection process, and a moving average value for each set number of the sampled sampling values is obtained. The opening timing of the intake valve 9 is detected based on the moving average value. That is, the control unit H determines that the timing at which the pressure detection value starts to rise from the time when the pressure detection value (moving average value) of the pressure sensor 21 becomes the lowest value is the timing at which the intake valve 9 opens in each cylinder 6 Is detected as being. When determining the timing, the rotational phase of the compression top dead center of the reference cylinder 6a obtained in the TDC detection process is used as a reference.
[0035]
In addition, FIG. 7 shows a change in the pressure detection value of the pressure sensor 21 when the crankshaft 4 is rotated in the forward rotation direction by the external driving means 3 with reference to the information on the rotation angle of the crankshaft 4. Is associated with the change in the pressure inside each cylinder and the operation timing of the intake valve 9 and the exhaust valve 10. Incidentally, in FIG. 7, # 1 indicates the reference cylinder 6a, # 2 indicates the second cylinder 6, # 3 indicates the third cylinder 6, and # 4 indicates the fourth cylinder 6, “EX” indicates a state where the exhaust valve 10 in each cylinder 6 is open, and “IN” indicates a state where the intake valve 9 in each cylinder 6 is open. As is apparent from this figure, when the intake valve 9 is opened in any of the cylinders 6, the pressure inside the intake manifold 17 begins to rise. That is, in the cylinder, when the piston rises and is almost close to top dead center, when the intake valve 9 is opened, the air pushed out by the piston raising operation is pushed out to the intake manifold 17 side. This is because the pressure inside the intake manifold 17 temporarily increases, and thereafter gradually decreases due to the intake operation.
[0036]
[Another embodiment]
(1) In the above embodiment, in the compression top dead center detection process, the first preliminary compression top dead center TDC (Y1) and the second preliminary compression top dead center TDC (Y2) are respectively determined in one cycle. Although it calculates | requires one by one and calculates | requires compression top dead center from them, it is not restricted to such a structure, The process which calculates | requires 1st preliminary | backup compression top dead center TDC (Y1) as mentioned above, and 2nd The process of obtaining the preliminary compression top dead center TDC (Y2) is repeated a plurality of times, and the average value of the plurality of first preliminary compression top dead centers and the average value of the plurality of second preliminary compression top dead centers are Based on the above, the compression top dead center may be obtained.
[0037]
(2) In the above embodiment, when the first preliminary compression top dead center is obtained and when the second preliminary compression top dead center is obtained, the detected pressure value is sampled every set period. The moving average value for each set number of the sampled sampling values is obtained, but instead of such processing, a peculiar change that locally changes such that the rate of change of the detected value is equal to or greater than the set value. The present invention can be implemented in various forms such as a process that removes data or a configuration that inputs data to the control unit through a low-pass filter that removes high-frequency components.
[0038]
(3) In the above embodiment, the diesel engine is exemplified as the test target engine, and the pressure sensor 14 as the pressure detecting means is connected using the mounting hole 13 for mounting the fuel injection nozzle. The test target engine is not limited to a diesel engine, and may be a gasoline engine. In that case, the pressure detection means may be connected using a mounting hole for mounting a spark plug.
[0039]
(4) In the above-described embodiment, the test is performed in a state where the test target engine is transported to a predetermined test setting position by the transport device and fixed in position, but instead of such a configuration, for example, transport You may apply to the engine test apparatus which tests an engine, moving in the state synchronized with the conveyance conveyor with respect to the engine to be conveyed in the state in which the engine to be tested is conveyed by the conveyor etc. Further, the connection work between the crankshaft and the external drive means, the connection work of various sensors, and the like may be automatically performed using an automatic connection device instead of the manual work.
[0040]
(5) In the above-described embodiment, the external drive means rotates the crankshaft by the rotation operation of the electric motor, but various drive means such as a hydraulic motor can be applied.
[0041]
(6) In the above embodiment, a four-cylinder engine has been exemplified as the test target engine. However, the number of cylinders of the engine to be tested can be changed as appropriate, and the intake air of the engine to be tested can be changed. The number of valves and exhaust valves can be changed as appropriate, and various engines can be adapted as test engines.
[0042]
(7) In the above embodiment, the example in which the compression top dead center detection device for the test target engine according to the present invention is applied to the engine test device has been described. It can also be applied to various devices related to engine testing.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of an engine test apparatus. FIG. 2 is a schematic diagram of an engine to be tested. FIG. 3 is a diagram showing a connection state of a pressure sensor. FIG. 4 is a flowchart of a control operation. 6] Timing chart for detection of compression top dead center [Fig. 7] Graph showing the relationship between engine operating condition and pressure fluctuation [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Test object engine 2 Electric motor 3 External drive means 4 Crankshaft 5 Rotation phase detection means 9 Intake valve 10 Exhaust valve 14 Pressure detection means 16 Buffer part H for pressure reduction Calculation means

Claims (3)

An external drive means connected to the crankshaft of the engine under test and forcibly rotating the crankshaft;
Pressure detecting means for detecting a pressure in a cylinder of the engine under test;
Rotational phase detection means for detecting the rotational phase of the crankshaft;
Computation means for obtaining a compression top dead center of the engine based on detection information of the pressure detection means and the rotation phase detection means in a state where the crankshaft is rotated by the external drive means. A compression top dead center detection device for a test target engine,
The external driving means is
The crankshaft is configured to be switchable between a state of rotating the crankshaft in a normal rotation direction and a state of rotating in the reverse rotation direction,
The computing means is
In the state where the crankshaft is rotated in the normal rotation direction by the external drive means, the cylinder inside the cylinder in one cycle of the test target engine based on the pressure detection value detected by the pressure detection means. Determining the rotational phase of the crankshaft when the pressure of the engine reaches the maximum value as a first preliminary compression top dead center; and
In a state where the crankshaft is rotated in the reverse rotation direction by the external drive means, the pressure in the cylinder is maximized during the one cycle based on the pressure detection value detected by the pressure detection means. The rotational phase of the crankshaft when the second preliminary compression top dead center is obtained, and
A test object configured to obtain a rotational phase of the crankshaft positioned at the center between the first preliminary compression top dead center and the second preliminary compression top dead center as the compression top dead center of the engine. Engine compression top dead center detector. The computing means is
When determining the first preliminary compression top dead center and when determining the second preliminary compression top dead center,
The pressure detection value detected by the pressure detection means is sampled at each set cycle, and a moving average value for each set number of the sampled sampling values is obtained, and the moving average value is maximum in the one cycle. 2. The engine under test according to claim 1, wherein the rotation phase of the crankshaft when the value reaches a value is obtained as the rotation phase of the crankshaft when the pressure in the cylinder reaches a maximum value during the one cycle. Compression top dead center detector. The compression top deadline inspection of the engine to be tested according to claim 1 or 2, wherein the pressure detecting means is configured to be connected to a cylinder of the engine to be detected via a buffer for reducing pressure. Out device.

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