JPH07128111A - Engine measuring device - Google Patents

Abstract

(57) [Summary] [Purpose] To provide an engine measuring device capable of measuring actual specifications of an engine such as a displacement and a compression ratio when the engine is assembled. A volume measuring means (10, 1) for measuring a volume of a combustion chamber of an engine when the engine is assembled.
1, 17, etc.), the rotation angle measuring means 7b for measuring the rotation angle of the crankshaft, the measurement results of the volume measuring means and the rotation angle measuring means, and the rotation of the crankshaft with the intake and exhaust valves closed. The engine displacement, compression ratio, stroke, connecting rod length, crank radius, and cylinder bore are measured using multiple measurements of combustion chamber volume measured at different rotational angles over a range of angles. An engine measuring device comprising: a computing means (19 or the like) for determining at least one of the diameter and the diameter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring various parameters such as displacement and compression ratio of an engine in an assembled state.

[0002]

2. Description of the Related Art As a conventional engine measuring device, there is one disclosed in, for example, Japanese Patent Laid-Open No. 60-76623. This device uses an acoustic volume measuring device that uses a Helmholtz resonator to measure the volume of the combustion chamber (the combustion chamber volume in the narrow sense) when the piston is at the top dead center position with the engine assembled. To do. Other engine measuring devices include compression ratio meter V from Ono Sokki Co., Ltd.
M-7100 is commercially available. This uses an acoustic volume measuring device that measures volume by measuring sound pressure, measures the volume of the combustion chamber when the piston is at the top dead center position, and presets this measurement value. The compression ratio for each cylinder is measured by using the stroke volume.

[0003]

In the conventional engine measuring device as described above, the volume of the combustion chamber when the piston is at the top dead center position in the assembled state of the engine, that is, the volume of the combustion chamber in the narrow sense is calculated. Although it is possible to measure, it was not possible to measure the combustion chamber volume when the piston was at the bottom dead center position, so it was not possible to obtain the actual displacement, and the combustion chamber volume at bottom dead center was determined. It was not possible to obtain the actual compression ratio to be calculated by using it. The reason why the combustion chamber volume at the bottom dead center cannot be measured as described above is as follows. That is, when an acoustic measuring device is used, it is necessary that the measurement target is a closed container, but an intake valve and an exhaust valve (abbreviated as intake and exhaust valves below) are provided in the combustion chamber of the engine. Is provided, and both of them are closed and the combustion chamber is sealed only when the crank angle is within a predetermined angle centered on the top dead center position, and the piston is located at the bottom dead center position. In the case of, since the valve is open, acoustic measurement cannot be performed.

The present invention has been made in order to solve the problems of the prior art as described above, and it is possible to measure actual parameters of the engine such as the displacement and the compression ratio when the engine is assembled. It is an object of the present invention to provide an engine measuring device capable of performing the above.

[0005]

In order to achieve the above object, the present invention is constructed as described in the claims. That is, in the invention described in claim 1, in the assembled state of the engine, volume measuring means for measuring the volume of the combustion chamber of the engine, rotation angle measuring means for measuring the rotation angle of the crankshaft,
The measurement results of the volume measuring means and the rotation angle measuring means are input, and a plurality of measurement values of the combustion chamber volume measured at a plurality of different rotation angles in the rotation angle range of the crankshaft with the intake and exhaust valves closed are displayed. Using the engine displacement, the compression ratio, the stroke, the connecting rod length, the crank radius, and the cylinder / bore diameter, the calculation means is provided. There is. The engine displacement may be at least one of the displacement of each cylinder, that is, the stroke volume, and the displacement of all cylinders, that is, the total stroke volume. The above-mentioned rotation angle measuring means, as described in the embodiment of FIG.
An angle detecting means such as a rotary encoder may be attached to the crankshaft to detect the angle directly,
Alternatively, as described in claim 2, the crankshaft may be rotated at a constant speed by a motor or the like, and the rotation angle may be measured from the rotation time. Alternatively, after the crankshaft is rotated by a motor for a predetermined angle and then stopped, the volume measuring means is measured at that time, and the crankshaft is again rotated by a predetermined angle, and the operation is repeated a predetermined number of times to perform measurement. May be configured to be automated. Further, the invention described in claim 3 uses the measurement result of the piston movement amount measuring means for measuring the piston movement amount instead of the crank angle in the first aspect. Further, the volume measuring means in claim 1 or 2 is an acoustic measuring means using a Helmholtz resonator as described in claim 4, and is mounted through an ignition plug hole of the engine. is there. In addition, in the invention described in claim 5, in addition to the configuration of the invention described in claims 1 to 4, based on a calculation result of the calculation means, a measured value of an engine as an object to be measured is predetermined. The determination means for determining whether or not the value is within the reference range and the display means for displaying the determination result are provided.

[0006]

In the present invention, for example, the volume of the combustion chamber is obtained by using acoustic volume measuring means utilizing a Helmholtz resonator. However, the volume of the combustion chamber at the bottom dead center required for determining the engine displacement and the like cannot be directly measured because the intake and exhaust valves are open at the bottom dead center. Therefore, in the present invention, when the combustion chamber is in a sealed state, that is, in the crank angle range in which the intake and exhaust valves are fully closed, the combustion chamber volumes at a plurality of different rotation angles are measured, and (Eg 3 pieces)
The combustion chamber volume at the bottom dead center is obtained from the equation (1) by obtaining the unknowns L, r, A, etc. in the equations (1) and (2) described below from the measured value of (1). Next, the combustion chamber volume at the top dead center determined by the measurement (the combustion chamber at the top dead center can be directly measured because the combustion chamber is closed) is subtracted from the combustion chamber volume at the bottom dead center obtained by the above calculation. As a result, the displacement (stroke volume) of the cylinder can be obtained. Therefore, the exhaust amount of the entire engine (total stroke volume) is calculated by multiplying the value of the exhaust amount by the number of cylinders n, or by measuring and calculating all the cylinders to obtain the exhaust amount of each cylinder and adding them. ) Can be asked. As described above, in the present invention, as the exhaust gas amount, either the exhaust gas amount of each cylinder, that is, the stroke volume, or the exhaust gas amount of all cylinders, that is, the total stroke volume, can be measured. Further, the compression ratio is obtained by the ratio of the combustion chamber volume at the bottom dead center to the combustion chamber volume at the top dead center. Further, the connecting rod length L, the crank radius r, and the cylinder / bore cross-sectional area A are obtained in the process of calculating the combustion chamber volume. Then, the cylinder / bore diameter B is obtained from the cylinder / bore cross-sectional area A by, for example, the following formula (Equation 9). Also, the stroke s
Corresponds to the piston movement amount when the crankshaft is rotated to the bottom dead center based on the piston position at the top dead center. This value can be directly measured, but as shown in FIG. 4 below, since there is a relation of s = 2r, the value of the crank radius r obtained in the process of calculating the combustion chamber volume at the bottom dead center is used. It is also possible to calculate. In the present invention, since it is possible to accurately and easily measure the engine specifications such as the actual displacement and the actual compression ratio in the engine assembled state, which could not be measured conventionally, it is possible to perform the experiment, the research and the factory line of the engine. Not only can it be used for inspections, but it will also be possible to easily inspect illegally modified vehicles and imported vehicles at the time of vehicle inspection, which was difficult in the past.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.
FIG. 1 is a sectional view of an embodiment of the present invention. In FIG. 1, the engine 1 is in an assembled state and in a stopped state. Reference numeral 2 is an engine block, 2a is a cylinder, 3 is a gasket, 4 is a cylinder head, and 5 is a head cover. 6 is a piston, 7 is a connecting rod, and the piston 6 is in a stopped state at the top dead center position. In this case, the intake valve and the exhaust valve (both not shown) are fully closed, and the combustion chamber 8 is a space closed to the outside. Further, 9 is a sensor head of a volume measuring means, inside which a cylindrical cavity 12 having a length d ′ and an internal volume V ′ and an acoustic tube 1 having a length d and an internal cross-sectional area S are provided.
3 and 3 constitute a Helmholtz resonator. This sensor head 9 is inserted into a spark plug hole 14 of the engine 1, and a cavity 12, an acoustic tube 13 and a combustion chamber 8 form a main acoustic resonator (acoustic closed to the outside with a cavity connected to both ends of the tube). System) is configured. A screw having the same shape as that of the spark plug is processed at the connecting portion of the sensor head 9 so that the sensor head 9 is screwed into the spark plug hole 14 for connection. A sound source 11 acoustically drives the air inside the main acoustic resonator. Reference numeral 10 denotes a microphone that detects the sound pressure inside the main acoustic resonator, and is mounted at the position shown in the figure. As described above, the reason why the main acoustic resonator is a space closed to the outside is
This is to prevent disturbance (such as noise from the outside) from entering and to perform accurate and stable measurement. However, if the main acoustic resonator is completely sealed, the crankshaft 7a
When the position of the piston 6 is moved by rotating, the air pressure and temperature in the combustion chamber 8 change, and the measurement fluctuates accordingly. Therefore, the air introduction pipe 30 is provided to prevent this. The air introducing pipe 30 is, for example, a thin pipe, can be regarded as a substantially acoustically closed state with a large acoustic resistance, and when the crankshaft 7a is gently rotated, the air is introduced accordingly. It comes in and goes out, and the atmospheric pressure inside can be kept at atmospheric pressure.
Even if the air introducing pipe 30 cannot be acoustically ignored, there is no problem if the air introducing pipe 30 is calibrated (described later) with the air introducing pipe 30 provided. Further, in FIG. 1, the case where the air introduction pipe 30 is provided at the upper end portion of the sensor head 9 is illustrated, but it may be provided at another portion. Further, 7a is a crankshaft, and a rotation angle detector 7b for detecting this rotation angle is attached.

FIG. 3 is a perspective view when a rotary encoder is used as the rotation angle detector 7b. In FIG. 3, a rotation angle detector 7b is connected to the crankshaft 7a via a jig 7c. Then, it is fixed to an appropriate place around by the fixing jig 7d. Further, the position of the piston 6 can be moved by rotating the crankshaft 7a by engaging and rotating the jig 7c with, for example, a hexagonal wrench 7e. In addition, in FIG.
The state before connecting the rotation angle detector 7b to the crankshaft 7a via the jig 7c is shown.

Next, FIG. 2 is a block diagram of an embodiment showing the configuration of the arithmetic means. In FIG. 2, reference numeral 15 is an oscillator, and this output signal Es (t) drives the sound source 11 via the sound source amplifier 16 and is input to the FFT analyzer (fast Fourier transform analyzer) 17. A microphone amplifier 18 amplifies the output signal Em (t) of the microphone 10 to an appropriate level and sends it to the FFT analyzer 17. A CPU 19 controls all the operations of the FFT analyzer 17, the oscillator 15, and the memory 20, performs a predetermined calculation using the measured values, and outputs the result to the display device 21. As the display device 21, for example, a display device such as a liquid crystal display device, a device for sending a hard copy such as a printer, or both of them can be used. Reference numeral 22 is a processing circuit for the rotation angle detector 7b, through which the rotation angle information of the crankshaft 7a is sent to the CPU 19.
Reference numeral 23 is a keyboard for inputting various data and command signals from the outside to the computing means.

Next, the operation will be described. First, the spark plug of the cylinder to be measured is removed, and the crankshaft 7a is rotated so that the cylinder becomes the top dead center. In this case, the hexagon wrench 7e or the like is used for rotation as described above, and the piston position is measured as shown in FIG. FIG. 7 is a diagram showing the relationship between the volume V of the combustion chamber 8 and the rotation angle θ of the crankshaft 7a in a 4-cycle engine. In FIG. 7, V _T is the volume at the top dead center,
V _B is the volume at the bottom dead center, and at the top dead center θ = 0 (d
eg). In the case of a general reciprocating engine, the relationship of V-θ in FIG. 7 is expressed by the following (Formula 1) and (Formula 2) using the general formula of the piston position x. V = (L + r−x) A + V _T (Equation 1) x = rcos θ + √ (L ² −r ² sin ² θ) (Equation 2) However, L: connecting rod length, r: crank radius, A: cylinder bore Cross-sectional area The relationship between the piston position x, the connecting rod length L, the crank radius r, the crankshaft rotation angle θ, etc. is as shown in FIG. Further, the relationship between the equations (1) and (2) is described, for example, in "Vehicle Technology Handbook: Fundamentals and Theory", Automotive Engineering Society, pp. 71-72.

Next, a procedure for measuring the volume of the combustion chamber at the top dead center by the volume measuring means shown in FIG. 1 will be described. In response to a command from the CPU 19 of FIG. 2, the oscillator 15 oscillates a signal having flat frequency characteristics, for example, a signal Es (t) such as a sine wave composite wave or white noise, and the sound source amplifier 1
The sound source 11 is driven via 6. As a result, the following resonance occurs in the main acoustic resonator. The main acoustic resonator of the present embodiment is one in which the cavity of the combustion chamber 8 and the cylindrical cavity 12 are connected to both ends of the acoustic tube 13. This means that two cavities are connected in parallel to one acoustic tube, that is, the main acoustic resonator is composed of three acoustic elements, and its resonance frequency f ₁ is given by ) As shown in the equation. f ₁ = (c / 2π) √ [S (V + V ′) / dVV ′] (Equation 3) where c: speed of sound, S: internal cross-sectional area of acoustic tube 13, d:
Length of acoustic tube 13, V: volume of combustion chamber 8, V ': cavity 1
Further, since the cylindrical cavity 12 is regarded as an acoustic tube whose both ends are closed, its resonance frequency f ₂ is expressed by the following (Equation 4). f ₂ = c / 2d ′ (and an integral multiple frequency) (Equation 4) Note that the resonance frequency f ₂ is a value represented by the above (Equation 4) expression and an integral multiple frequency thereof. The description will be given using the lowest order frequency. Tube resonance frequency f
₂ has the maximum pressure vibration at both ends, so that the microphone 10 and the sound source 11 have a cylindrical cavity 1 as shown in FIG.
It is attached to the end of 2. The sound pressure inside the main acoustic resonator at this time is detected by the microphone 10, and the output signal Em (t) of this microphone is detected by the microphone amplifier 1
8 to the FFT analyzer 17. Where CP
In response to the command from U19, the FFT analyzer 17 causes the sound source 1
The signal Es (t) to 1 is input, and the microphone output signal E
Calculate the transfer function with m (t) as output. CPU 19
When this calculation is completed, the oscillation of the oscillator 15 is stopped.
The operations of the FFT analyzer 17 and the oscillator 15 up to this point are all performed in synchronization by the CPU 19. The transfer function obtained by the FFT analyzer 17 as described above is shown in FIG.
As shown in, the amplitude characteristic | H at the resonance frequency f ₁
In the case of |, there is a peak, and in the case of phase characteristic ∠H, there is an inversion characteristic.
Although only the resonance frequency f ₁ is shown in FIG. 6, the same measurement is performed at the resonance frequency f ₂ . These resonance frequencies f ₁ and f ₂ can be roughly estimated in advance from the dimensions of the acoustic tube 13 and the cavity 12 and the temperature at the time of measurement using the above equations (3) and (4). is there. CP
U19 takes in the above transfer function data, and determines each resonance frequency f from the peak frequency value of the amplitude characteristic or the frequency value at the intersection point of the phase φ at the resonance point and the phase characteristic obtained in advance by experiments or the like. Calculate ₁ and f ₂ . The volume V of the combustion chamber is calculated from the above two resonance frequencies f ₁ and f _{2 as} follows. That is, from the equations (3) and (4), the sound velocity c
When is deleted, the following equation (5) is obtained. _{V = k (f 2 / f} 1) 2 V '/ {V'-k (f 2 / f 1) 2} ... ( 5) ^{However, k = d' 2 S /} π 2 d above (5) Where the internal cross-sectional area S of the acoustic tube 13 is
Since the length d of the acoustic tube 13 and the volume V ′ of the cavity 12 are known values, the volume V of the combustion chamber 8 can be calculated by substituting the two resonance frequencies f ₁ and f ₂ into the equation (5). You can ask. In this case, the volume of the combustion chamber at the top dead center is defined as V _T. However, equation (3),
The equation (4) is a theoretical equation under ideal conditions, and when the above equation (5) obtained from these is used, a measurement error may occur. Therefore, the actual calculation formula may be an approximate formula using a constant k ′ experimentally obtained by performing a calibration experiment using a container of known volume and dimensions.

Next, the procedure for measuring the volume V _i of the combustion chamber 8 when the crankshaft 7a is rotated by an arbitrary angle i will be described. However, since the acoustic volume measuring means is used in this embodiment, the combustion chamber as the object to be measured needs to be a space closed from the outside. for that reason,
The range of the angle i is limited to the section where the intake / exhaust valve is closed. The fully closed section of both valves is, for example, the range of h shown by the solid line in FIG. 7, and is ± 12 around the top dead center.
The range is about 0 ° to 130 °. In order to measure at such an angle i, as shown in FIG.
the crankshaft 7a at an arbitrary angle i [de
g], and the volume V _i of the combustion chamber at this time is measured. The measuring method is the same as the above measuring at the top dead center. The rotation angle i is detected by the rotation angle detector 7b and sent to the CPU 19 via the processing circuit 22. The above-described measurement of the volume V _i and the angle i is performed at three or more angles including the top dead center, and the obtained measured values are substituted into the equations (1) and (2). , The connecting rod length L, the crank radius r, and the bore cross-sectional area A of the cylinder of the equation (1), which are unknowns, are obtained. Then, the obtained L, r, A
From the equation (1), θ = 180 [deg], that is, the volume V _B of the combustion chamber at the bottom dead center can be obtained.

The rotation of the crankshaft 7a can be automatically performed by using a motor or the like. Then, if the crankshaft is rotated at a constant angular velocity by the motor and measurement is performed at predetermined intervals, the crank angle that rotates in a constant time is constant, so there is no need to measure the crank angle each time. Therefore, the rotation angle measuring means can be eliminated. By controlling the constant-speed rotation driving by the motor and the measurement at regular time intervals by the CPU 19, it is possible to automatically measure a plurality of points in the valve fully closed section, and from these values, the bottom dead center is determined. It is possible to automatically determine the volume V _B of the combustion chamber at. Alternatively, the measurement is performed by repeating the operation of rotating the crankshaft by a predetermined angle with a motor, stopping the crankshaft, then measuring by the volume measuring means, and rotating the crankshaft by a predetermined angle again a predetermined number of times. It may be configured to be automated.

Next, assuming that the number of cylinders of the engine 1 set in advance using the keyboard 23 is n, the desired engine 1
The total displacement W and the compression ratio ε are calculated by the following equations (6) and (7). W = n (V _B −V _T ) (Equation 6) ε = V _B / V _T (Equation 7) Furthermore, the bore cross-sectional area A of the cylinder 2a and the volume measurement values V _B , V _T obtained previously Also, the stroke s of the cylinder to be measured can be calculated from the following equation (8). s = (V _B −V _T ) / A (Equation 8) Further, the bore diameter B can be obtained from the bore cross-sectional area A by the following (Equation 9) formula. B = 2√ (A / π) (Equation 9) The CPU 19 outputs the above calculation results to the display device 21, and the display device 21 displays the calculation result by the display on the screen or the hard copy.

In the present embodiment, unknown values such as V _B and L were obtained from the measured values at two or more places at the top dead center and an arbitrary crank angle, or at three or more places in total. If the crank angle is not included, the above-mentioned specifications can be obtained from the measured values at four or more places. However, as described above, the crank angle measured above is in the angular range in which the intake and exhaust valves are fully closed. Further, as the method of detecting the top dead center in the present embodiment, as shown in FIG. 5, a method of directly measuring from the hole of the ignition plug using a measuring device 24 such as a dial gauge may be used. It can also be detected by using the volume measuring means. That is, from the relationship between the volume V of the combustion chamber and the resonance frequency ratio (f ₂ / f ₁ ) ^{2 in the} equation (5), the point where (f ₂ / f ₁ ) ² becomes the minimum is the top dead center. If used, CPU19
Can automatically detect the top dead center. For example, the volume value V of the formula (5) or the resonance frequency ratio (f ₂ / f ₁ ) ²
(Note that f ₂ / f ₁ may be used) is output to an external monitor (for example, the display device 21), and the operator may rotate the crankshaft 7a so as to minimize the monitor value while watching this. FIG. 8 is a flowchart showing the measurement procedure of the present embodiment described so far. In FIG. 8, first, the number of cylinders n is input from the keyboard 23 in step S1. Also, steps S5 and S
The measurement at angle i in 6 shall be repeated at least twice. Further, in step S8, bottom dead center volume V _B , connecting rod length L, crank radius r, and cylinder-bore cross-sectional area A are calculated from V _T , i, and V _i obtained in steps S4, S5, and S7. Further, in this embodiment,
The displacement W was calculated from the measured value for one cylinder and the preset number of cylinders n by the formula (6). However, if the above measurement is performed for all cylinders, the displacement W should be calculated more accurately. You can That is, the stroke volume (V
_B -V _T) the determined, the sum is the exhaust quantity. In that case,
If the volume measuring means is prepared for the number of cylinders and each cylinder is measured at the same time, the volume measuring means does not have to be detached and relocated for each cylinder, so that the measurement can be performed in a shorter time. The volume measuring means, the resonance frequency measuring method, and the volume calculation formula are not limited to those described in the present embodiment.

Next, in the embodiments described so far, the unknown number in the equation (1) is obtained from the measured values at three or more crank angles, and the volume V _B at the bottom dead center is obtained. However, if the measurement with high accuracy is not required, the relational expression of V-θ in the equation (1) can be approximated by a sine curve to be expressed as the following equation (10). V = {− (V _B −V _T ) / 2} cos θ + (V _B + V _T ) / 2 (Equation 10) Therefore, the volume V _{i at the} crank angle _i is (Equation 1
From the equation (0), the following equation (11) is obtained. V _i = {− (V _B −V _T ) / 2} cosi + (V _B + V _T ) / 2 (Equation 11) In Equation (11), V _T , V _i, and i are obtained as measured values. The volume V _B at the bottom dead center is calculated from the equation (11) as the following equation (12). V _B = {2V _i −V _T (1 + cosi)} / (1−cosi) (Equation 12) As described above, when the relational expression of V−θ in (Equation 1) is approximated by a sine curve, Can calculate the combustion chamber volume V _B at the bottom dead center based on the volume V _{T at} the top dead center and the measurement result at one crank angle i, that is, the measurement results at two places in total. Furthermore, as another embodiment, there is a method of estimating the volume V _B at the bottom dead center as follows. That is, generally, the change in the volume of the combustion chamber near the bottom dead center is small with respect to the change in the crank angle θ, and the ratio of the connecting rod length L of the normal engine to the crank radius r is L / r = 3.5-4. The measurement of the volume V is performed at two points, the top dead center and the crank angle θ≈ ± h / 2, which is the closest to the bottom dead center in the valve fully closed section h. The volume V _B at the bottom dead center can be estimated from the relationship such as / r. The method of measuring and calculating the bottom dead center volume V _B is not limited to this example.

Next, a second embodiment of the present invention will be described. In this embodiment, the rotation angle θ of the crankshaft 7a
Instead of measuring, the moving amount of the piston 6 is measured, and the exhaust amount W, the compression ratio ε, etc. are obtained based on the measured values. The piston movement amount measuring means for measuring the movement amount of the piston 6 is a measuring device 24 such as a dial gauge as shown in FIG. 5, and measures the movement amount of the piston 6 directly from the piston crown surface 6a. is there. The measuring device 24 may of course be a displacement meter or a distance meter using ultrasonic waves or laser. If the moving amount of the piston 6 is St,
The relationship between the piston movement amount St and the crank angle θ is as shown in FIG. 9, and has the same characteristics as the V-θ diagram of FIG. 7. Therefore, the piston movement amount St and the volume V of the combustion chamber 8
The relationship between and becomes a proportional relationship as shown in FIG. In addition, in FIG. 9, the angle of the horizontal axis indicates the top dead center at θ = 0 [de
g], and the piston movement amount St on the vertical axis is 0 at the top dead center. Here, the movement amount at bottom dead center, that is, the stroke is s, the piston movement amount at an arbitrary crank angle j is p, and the combustion chamber volume at this time is V _p .

The measuring method of this embodiment will be described below. First, similarly to the first embodiment, the cylinder to be measured is set to the top dead center using the measuring device 24, and the volume V _T of the combustion chamber 8 at this time is measured. Next, the crankshaft 7a
Is rotated by an arbitrary angle j in the valve fully closed section h, and the moving amount p of the piston 6 at this time is measured. Further, the crankshaft 7a is rotated to the bottom dead center, and the piston movement amount at this time, that is, the stroke s is measured.
Here, the relationship between V and St shown in FIG.
It is shown by the equation 3). V = {(V _p −V _T ) / p} St + V _T (Equation 13) Therefore, the combustion chamber volume V _B at the bottom dead center is measured values V _T and V _{T.
From p 1} and p 2 and the formula (13), the formula (14) is obtained. V _B = {(V _p −V _T ) / p} s + V _T (Equation 14) From the combustion chamber volume V _B at the bottom dead center obtained as described above, the above (Equation 6) equation, (Equation 7) The displacement W and the compression ratio ε can be calculated using the equations. Further, the bore diameter B of the cylinder 2a is calculated from the above measured values V _B , V _T , and s by
It is calculated by the equation (5). B = 2√ [(V _B −V _T ) / sπ] (Equation 15) Further, in the above (Equation 1), (L + r−x) is equal to the piston movement amount St. That is, the formula 1 and the formula 1
Since Expression 3) shows the same thing, the connecting rod length L and the crank radius r can be obtained from the measured value of the piston movement amount St. Further, from the above-mentioned FIG. 4, since the stroke s has a relation of s = 2r, it can be calculated from the crank radius r.

Next, another embodiment relating to the method of connecting the sensor head 9 of the acoustic volume measuring means will be described. FIG. 11 is a cross-sectional view showing a main part near the upper portion of the combustion chamber 8. In FIG. 1, a screw having the same shape as that of the spark plug is processed at the connecting portion of the sensor head 9 so that the sensor head 9 is screwed into the spark plug hole 14 for connection. The present embodiment is for making preparation for measurement easier than in FIG. That is, as shown in FIG. 11, the diameter of the end portion of the sensor head 9 is made slightly smaller than that of the spark plug hole 14, so that the sensor head 9 is simply inserted without being screwed and is sealed with the surface 25. At this time, a minute gap is formed between the end of the sensor head 9 and the spark plug hole 14, but there is no problem if the above-described calibration is performed in a state including this.

Next, another embodiment of the volume measuring means will be described. FIG. 12 is a sectional view of the second embodiment of the volume measuring means. In this embodiment, the cavity of the combustion chamber 8 and the acoustic tube 13 are
And constitute a Helmholtz resonator, and the sound source 11 is arranged outside the resonator to vibrate. In this example,
This is a suitable example when the volume V ′ of the cavity 12 cannot be set sufficiently larger than the volume V of the combustion chamber 8 in the embodiment of FIG. 1, and one end of the acoustic tube 13 is open to the atmosphere by a hole 26. Since a large sound source having a higher reproduced sound pressure than that of the embodiment of FIG. 1 can be used, resonance is favorably generated. The resonance frequency f _{1 at} this time is as shown in the following equation (16). f ₁ = (c / 2π) √ (S / dV) (Equation 16) Resonance also occurs in the acoustic tube 13, and its resonance frequency f ₂ is represented by the following equation (17). f ₂ = c / 2d (and a frequency that is an integral multiple thereof) (Equation 17) If the sound velocity c is eliminated from the above Equations (16) and (17), the volume becomes as shown in the following (Equation 18). V is required. V = k (f ₂ / f ₁ ) ² (Equation 18) However, k = dS / π ² Equations 16 and 17 are theoretical equations under ideal conditions, When the formula (18) obtained from these is used, a measurement error may occur. Therefore, the actual calculation formula may be an approximate formula using a constant k ′ experimentally obtained by performing a calibration experiment using a container whose volume and dimensions are known.

Other configurations and operations are similar to those of the first embodiment. Next, FIG. 13 is a sectional view of a third embodiment of the volume measuring means. This embodiment is an effective embodiment when the sound source 11 cannot be arranged at the position shown in FIG. This extends the acoustic tube 13 to the outside of the engine 1,
Furthermore, by arranging the sound source 11 outside the sensor head 9, the sensor head 9 is not restricted by the size of the sound source 11 or the like.
Is designed so that it can be designed. Others are shown in FIG.
The description is omitted because it is the same as the embodiment described above. In the embodiment shown in FIGS. 12 and 13, the hole 26 opened to the atmosphere is used.
Is provided in order to favorably generate resonance even when the sound source 11 having a large equivalent capacity is used.
Further, since the hole 26 that is open to the atmosphere is provided in this way, it is not necessary to provide the air introduction pipe 30 of FIG.

Next, an embodiment for determining whether or not the measured value of the engine, which is the object to be measured, is within the predetermined reference range based on the measurement result will be described. In the above-described embodiments, the measurement result is simply displayed on the display device 21. In this embodiment, the design value or the like of the engine, which is the object to be measured, is stored in the memory 20 as a reference value in advance, or is input from the keyboard 23, and the reference value is compared with the measured value. If the comparison result is within a predetermined permissible range such as a preset design standard, the result is acceptable. If the comparison result is not within the permissible range, it is determined that the measured engine has an abnormality, and the abnormality content is output to the display device 21. It is configured to be displayed. With this configuration, it is possible to easily determine whether or not the engine complies with the set standard or is illegally modified. These operations may be programmed so that the CPU 19 automatically uses the measurement results.
Further, the content of comparison, the reference value, etc. may be appropriately prepared according to the application, and are not limited to the present embodiment.

[0023]

As described above, according to the present invention, the combustion chamber volume is measured at a plurality of piston positions in the range where the intake / exhaust valve is fully closed, and the combustion at bottom dead center is measured from these values. By configuring to calculate the chamber volume, it is possible to accurately and easily measure the engine specifications such as the actual displacement and actual compression ratio in the engine assembled state, which could not be measured conventionally. To be Therefore, by using the present invention, not only can it be used for engine experiments, research, inspections in factory lines, etc., but it is also easy to inspect illegally modified vehicles and imported vehicles at the time of vehicle inspection, which was difficult in the past. Will be possible.

[Brief description of drawings]

FIG. 1 is a sectional view of a first embodiment of the present invention.

FIG. 2 is a block diagram showing the configuration of a calculation unit.

FIG. 3 is a perspective view showing a mounting state of a rotation angle detection device.

FIG. 4 is a diagram showing a relationship among a connecting rod length L, a crank rotation angle θ, and a piston position x.

FIG. 5 is a sectional view showing a method for measuring the amount of movement of a piston.

FIG. 6 is a characteristic diagram of a transfer function.

FIG. 7 is a V-θ characteristic diagram showing the relationship between the combustion chamber volume V and the crank angle θ.

FIG. 8 is a flowchart showing the measurement procedure of the first embodiment.

FIG. 9 is a St-θ characteristic diagram showing the relationship between the piston movement amount St and the crank angle θ.

FIG. 10 is a V-St characteristic diagram showing the relationship between the combustion chamber volume V and the piston movement amount St.

FIG. 11 is a sectional view showing another embodiment of the method of connecting the sensor heads.

FIG. 12 is a sectional view of a second embodiment of the sensor head.

FIG. 13 is a sectional view of a sensor head according to a third embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Engine 2 ... Block 2a ... Cylinder 3 ... Gasket 4 ... Cylinder head 5 ... Head cover 6 ... Piston 6a ... Piston crown surface 7 ... Connecting rod 7a ... Crankshaft 7b ... Rotation angle detector 7c ... Jig 7d ... Fixing jig 7e ... Hexagon wrench 8 ... Combustion chamber 9 ... Sensor head 10 ... Microphone 11 ... Sound source 12 ... Cavity 13 ... Acoustic tube 14 ... Ignition plug hole 15 ... Oscillator 16 ... Sound source amplifier 17 ... FFT analyzer 18 ... Head cover 19 ... CPU 20 ... Memory 21 ... Display device 22 ... Rotation angle detector circuit 23 ... Keyboard 24 ... Measuring instrument 25 ... Surface 26 ... Hole 30 ... Air introduction pipe

Claims (5)

[Claims] 1. When the engine is assembled,
The volume measurement means for measuring the volume of the combustion chamber of the engine, the rotation angle measurement means for measuring the rotation angle of the crankshaft, the measurement results of the volume measurement means and the rotation angle measurement means are input, and the intake and exhaust valves are closed. Using a plurality of measurement values of the combustion chamber volume measured at a plurality of different rotation angles in the range of crankshaft rotation angles, the engine displacement, compression ratio, stroke, connecting rod length, crank An engine measuring device comprising: a calculating means for determining at least one of a radius and a cylinder / bore diameter. 2. The engine measuring device according to claim 1, wherein the rotation angle measuring means rotates the crankshaft at a constant speed and measures the rotation angle from the rotation time. 3. When the engine is assembled,
The volume measuring means for measuring the volume of the combustion chamber of the engine, the piston moving amount measuring means for measuring the piston moving amount, the measurement results of the volume measuring means and the piston moving amount measuring means are inputted, and the intake and exhaust valves are closed. Using a plurality of measurement values of the combustion chamber volume measured at a plurality of different piston positions in the range of piston positions, the displacement of the engine, the compression ratio, the stroke, the connecting rod length, the crank radius, An engine measuring device comprising: a calculating means for determining at least one of a cylinder bore diameter. 4. The volume measuring means is an acoustic measuring means using a Helmholtz resonator, and is mounted through an ignition plug hole of an engine. The engine measuring device according to any one of 1. 5. A judging means for judging whether or not a measured value of an engine, which is an object to be measured, is within a predetermined reference range based on the calculation result of the calculating means, and the judgment result is displayed. The engine measuring device according to any one of claims 1 to 4, further comprising: a display unit.