JP3141651B2 - Engine measuring device - Google Patents

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 a displacement and a compression ratio of an engine in an assembled state.

[0002]

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

[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 a state where the engine is assembled, that is, the combustion chamber volume in a narrow sense is determined. Although it is possible to measure, the combustion chamber volume when the piston is at the bottom dead center position could not be measured, so the actual displacement could not be obtained, and the combustion chamber volume at the bottom dead center was calculated. It was not possible to determine the actual compression ratio to be calculated using this. The reason why the volume of the combustion chamber 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 (hereinafter, abbreviated as an intake / exhaust valve) are provided in a combustion chamber of the engine. It is only when the crank angle is within a predetermined angle around the top dead center position that the combustion chamber is closed when both of them are closed, and the piston is moved to the bottom dead center position. In this case, since the valve is open, acoustic measurement cannot be performed.

SUMMARY OF THE INVENTION The present invention has been made to solve the problems of the prior art as described above, and it is an object of the present invention to measure actual parameters of an engine such as a displacement and a compression ratio in a state where the engine is assembled. It is an object of the present invention to provide an engine measuring device capable of performing the following.

[0005]

Means for Solving the Problems In order to achieve the above object, the present invention is configured as described in the claims. That is, in the invention described in claim 1, in a state where the engine is assembled, a volume measuring means for measuring a volume of a combustion chamber of the engine, a rotation angle measuring means for measuring a rotation angle of a crankshaft,
The measurement results of the volume measurement means and the rotation angle measurement means are input, and a plurality of measured values of the combustion chamber volume measured at a plurality of different rotation angles in the range of the rotation angle of the crankshaft with the intake and exhaust valves closed. Using, computing means for obtaining at least one of the displacement of the engine, the compression ratio, the stroke, the connecting rod length, the crank radius, and the cylinder bore diameter, I have. 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 later in the embodiment of FIG.
Angle detection means such as a rotary encoder may be attached to the crankshaft to detect the angle directly,
Alternatively, 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, measurement is performed by repeating the operation of rotating the crankshaft by a predetermined number of times, rotating the crankshaft by a predetermined angle, stopping the motor after rotating the crankshaft by a predetermined angle, measuring by the volume measuring means, and rotating the crankshaft again by a predetermined angle. May be configured to be automated. According to a third aspect of the present invention, a measurement result of a piston movement amount measuring means for measuring a piston movement amount is used instead of the crank angle in the first aspect. The volume measuring means according to claim 1 or 2 is an acoustic measuring means using a Helmholtz resonator as described in claim 4, and is mounted via a spark plug hole of an engine. is there. According to a fifth aspect of the present invention, in addition to the configuration of the first to fourth aspects of the present invention, a measured value of the engine to be measured is determined based on a calculation result of the calculation means. And a display for displaying the result of the determination.

[0006]

In the present invention, for example, the volume of the combustion chamber is determined by using an 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 at the bottom dead center because the intake and exhaust valves are open. Therefore, in the present invention, when the combustion chamber is in a closed state, that is, in the crank angle range in which the intake and exhaust valves are fully closed, combustion chamber volumes at a plurality of different rotation angles are measured, and (For example, three)
For example, the unknowns L, r, A, and the like in Equations (1) and (2) described below are obtained from the measured values, and the combustion chamber volume at the bottom dead center is obtained from Equation (1). Next, the combustion chamber volume at the top dead center obtained by measurement (which can be directly measured at the top dead center because the combustion chamber is in a closed state) is subtracted from the combustion chamber volume at the bottom dead center obtained by the above calculation. Thus, the displacement (stroke volume) in the cylinder is obtained. Therefore, by multiplying the value of the displacement by the number n of cylinders, or by measuring and calculating all the cylinders to obtain the displacement of each cylinder and adding them, the displacement of the entire engine (total stroke volume) is obtained. ). As described above, in the present invention, it is possible to measure, as the displacement, either the displacement of each cylinder, that is, the stroke volume, or the displacement of all cylinders, that is, the total stroke volume. The compression ratio is determined by the ratio between the volume of the combustion chamber at the bottom dead center and the volume of the combustion chamber at the top dead center. 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. The cylinder / bore diameter B is obtained from the cylinder / bore cross-sectional area A by, for example, Expression (9) below. Also, the stroke s
Corresponds to the piston movement amount when the crankshaft is rotated to the bottom dead center with reference to the piston position at the top dead center. Although this value can be measured directly, as shown in FIG. 4 described below, since there is a relationship 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, the engine specifications such as the actual displacement and the actual compression ratio in the engine assembled state, which could not be measured conventionally, can be accurately and easily measured. Not only can it be used for inspection and the like, but also inspection of illegally modified vehicles and imported vehicles can be easily performed 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 one embodiment of the present invention. In FIG. 1, the engine 1 is in an assembled state and is in a stopped state. 2 is an engine block, 2a is a cylinder, 3 is a gasket, 4 is a cylinder head, and 5 is a head cover. Reference numeral 6 denotes a piston, 7 denotes a connecting rod, and the piston 6 is stopped 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. Reference numeral 9 denotes a sensor head of a volume measuring means, in 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 together form a Helmholtz resonator. The sensor head 9 is inserted into a spark plug hole 14 of the engine 1, and has a main acoustic resonator (an acoustic closed to the outside having a cavity connected to both ends of the tube) by a cavity 12, an acoustic tube 13 and a combustion chamber 8. System) is composed. The connection portion of the sensor head 9 is formed with a screw having the same shape as that of the ignition plug, and is screwed into the ignition plug hole 14 for connection. A sound source 11 acoustically drives air inside the main acoustic resonator. Reference numeral 10 denotes a microphone for detecting a sound pressure inside the main acoustic resonator, which is attached at a position as shown in the figure. As described above, the reason that the main acoustic resonator is a space closed to the outside is as follows.
This is to prevent the intrusion of disturbance (such as noise from the outside) and 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 due to the change. The air introducing pipe 30 is provided to prevent the fluctuation. The air introduction pipe 30 is, for example, a thin pipe, has a large acoustic resistance, can be regarded as a substantially sealed state, and when the crankshaft 7a is slowly rotated, the air is accordingly supplied. Comes in and out, and the internal pressure can be maintained at atmospheric pressure.
Even if the air introduction tube 30 cannot be ignored acoustically, there is no problem if calibration (described later) is performed with the air introduction tube 30 provided. FIG. 1 illustrates the case where the air introduction pipe 30 is provided at the upper end of the sensor head 9, but may be provided at another part. A crankshaft 7a is provided with a rotation angle detector 7b for detecting the rotation angle.

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 a crankshaft 7a via a jig 7c. Then, it is fixed to an appropriate surrounding area by a fixing jig 7d. In addition, the position of the piston 6 can be moved by rotating the crankshaft 7a by rotating the jig 7c with, for example, a hexagon wrench 7e. In FIG. 3,
This shows a state before a rotation angle detector 7b is connected to a crankshaft 7a via a jig 7c.

Next, FIG. 2 is a block diagram of one embodiment showing the configuration of the calculating means. In FIG. 2, reference numeral 15 denotes an oscillator. The output signal Es (t) drives the sound source 11 via a sound source amplifier 16 and is input to an FFT analyzer (fast Fourier transform analyzer) 17. Reference numeral 18 denotes a microphone amplifier, which amplifies the output signal Em (t) of the microphone 10 to an appropriate level and sends it to the FFT analyzer 17. Reference numeral 19 denotes a CPU, which controls all operations of the FFT analyzer 17, the oscillator 15, and the memory 20, performs a predetermined operation using the measured value, 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 transmitting a hard copy such as a printer, or both of them can be used. Reference numeral 22 denotes a processing circuit for the rotation angle detector 7b, through which rotation angle information of the crankshaft 7a is sent to the CPU 19.
Reference numeral 23 denotes a keyboard for externally inputting various data and command signals to the operation means.

Next, the operation will be described. First, the ignition 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 piston can be rotated using the hexagon wrench 7e or the like, and the piston position can be 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 four-cycle engine. In FIG. 7, V _T is the volume at top dead center,
V _B is the volume at the bottom dead center, and 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 (Equation 1) and (Equation 2) using the general expression of the piston position x. V = (L + r−x) A + V _T (Equation 1) x = r cos θ + √ (L ² −r ² sin ² θ) (Equation 2) where L: connecting rod length, r: crank radius, A: cylinder bore FIG. 4 shows the relationship among the piston position x, connecting rod length L, crank radius r, crankshaft rotation angle θ, and the like. Further, the relationship between the above-mentioned equations (1) and (2) is described in, for example, "" Automotive Technology Handbook Fundamentals / Theory ", Japan Society of Automotive Engineers, pages 71 to 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 Es (t) having a flat frequency characteristic, for example, a signal Es (t) such as a sine wave composite wave or white noise.
The sound source 11 is driven via 6. As a result, the following resonance occurs in the main acoustic resonator. In the main acoustic resonator of this embodiment, a cavity of the combustion chamber 8 and a cylindrical cavity 12 are connected to both ends of an 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 ) Expression. f ₁ = (c / 2π) √ [S (V + V ′) / dVV ′] (Expression 3) where c: sound velocity, S: internal cross-sectional area of the acoustic tube 13, d:
Length of acoustic tube 13, V: volume of combustion chamber 8, V ': cavity 1
2 volumes Furthermore, since the cylindrical cavity 12 is regarded as acoustic tube ends closed, the resonance frequency f ₂ is expressed by the following equation (4) below. f ₂ = c / 2d ′ (and an integer multiple of frequency) (Equation 4) Note that the resonance frequency f ₂ is a value represented by the above (Equation 4) and a frequency that is an integral multiple of the value. Description will be made using the lowest order frequency. The above tube resonance frequency f
₂ , the microphone 10 and the sound source 11 have cylindrical cavities 1 as shown in FIG.
2 at the end. At this time, the sound pressure inside the main acoustic resonator is detected by the microphone 10 and the output signal Em (t) of the microphone is output to the microphone amplifier 1.
8 to the FFT analyzer 17. Where CP
According to the command of U19, the FFT analyzer 17
1 to the microphone output signal Es (t).
Calculate the transfer function with m (t) as output. The 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 synchronously by the CPU 19. The transfer function obtained by the FFT analyzer 17 as described above is shown in FIG.
As shown in, at the resonant frequency f _1, the amplitude characteristics | H
| Indicates a peak, and the phase characteristic ΔH indicates a reversal characteristic.
Although in FIG. 6 describes only the resonance frequency f _1, it is also measured in the same manner at the resonance frequency f _2. The approximate values of these resonance frequencies f ₁ and f ₂ can be predicted 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 fetches the above transfer function data and calculates each resonance frequency f from the peak frequency value of the amplitude characteristic or the frequency value at the intersection of the phase φ at the resonance point and the phase characteristic, which has been obtained in advance through experiments or the like. _1, determine the f _2. To determine the volume V of the combustion chamber from the above two resonance frequencies f ₁ and f ₂ , the following is performed. That is, the sound speed c is obtained from the equations (3) and (4).
Is eliminated, the following equation (5) is obtained. V = k (f ₂ / f ₁ ) ² V ′ / {V′−k (f ₂ / f ₁ ) ² } (Equation 5) where k = d ′ ² S / π ² d The above (Equation 5) In the formula, 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 obtained by substituting the two resonance frequencies f ₁ and f ₂ into Equation (5). You can ask. In this case, the volume of the combustion chamber at the top dead center, which is referred to as V _T. However, (Equation 3),
Equation (4) is a theoretical equation under ideal conditions, and if the above equation (5) obtained from these equations is used, there is a possibility that 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 having a known volume and dimensions.

[0012] Next, a description will be given of a measuring procedure of the volume V _i of the combustion chamber 8 in the case of rotating the crankshaft 7a by an arbitrary angle i. However, in this embodiment, since the acoustic volume measuring means is used, the combustion chamber as the object to be measured needs to be a space closed from the outside. for that reason,
The range that the angle i can take is limited to the section where the intake and exhaust valves are closed. The fully closed section of both valves is, for example, a range of h shown by a solid line in FIG.
It is in the range of about 0 ° to 130 °. To measure at such an angle i, as shown in FIG.
e, etc., to set the crankshaft 7a at an arbitrary angle i [de
g] only rotate, the measurement of the volume V _i of the combustion chamber at this time. The measurement method is the same as the measurement 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 measurement of the volume V _i and the angle i as described above is performed at three or more angles including the top dead center, and the obtained measured values are substituted into the above equations (1) and (2). , The connecting rod length L, the crank radius r, and the bore area A of the cylinder are obtained from the unknown equation (Equation 1). Then, the obtained L, r, A
From 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 using a motor or the like. If the crankshaft is rotated at a constant angular velocity by the motor and the measurement is performed at predetermined intervals, the crank angle rotating for a predetermined time is constant, so that it is not necessary to measure the crank angle each time. Therefore, the rotation angle measuring means can be eliminated. If the CPU 19 controls the driving of the constant-speed rotation by the motor and the measurement at regular time intervals, the measurement at a plurality of points in the valve fully closed section can be performed automatically. the volume V _B of the combustion chamber can be automatically determined in. Alternatively, measurement is performed by repeating the operation of rotating the crankshaft by a predetermined angle by a motor, stopping the rotation at that time, measuring by the volume measuring means at that time, and rotating the crankshaft by the predetermined angle again a predetermined number of times. You may comprise so that it may be automated.

Next, assuming that the number of cylinders of the engine 1 set in advance using the keyboard 23 is n,
Is obtained by the following equations (Equation 6) and (Equation 7). W = n (V _B −V _T ) (Equation 6) ε = V _B / V _T (Equation 7) Further, the bore sectional area A and the measured volume values V _B , V _{T of} the cylinder 2a obtained previously are obtained. , The stroke s of the cylinder to be measured can also be obtained from the following equation (8). s = (V _B −V _T ) / A (Equation 8) Further, the bore diameter B can be obtained from the bore sectional area A by the following Equation (9). B = 2√ (A / π) (Equation 9) The CPU 19 outputs each calculation result to the display device 21, and the display device 21 displays the calculation result by display on a screen or hard copy.

[0015] In the present embodiment, more than two at the top dead center and an arbitrary crank angle, but the measurements at total three or more locations to determine the unknowns, such as V _B and L, and the top dead center If the crank angle is not included, the above specifications can be obtained from the measured values at four or more locations. However, as described above, the crank angle to be measured is an angle range in which the intake and exhaust valves are fully closed. Further, the method of detecting the top dead center in the present embodiment may use a method of directly measuring from the hole of the spark plug using a measuring device 24 such as a dial gauge as shown in FIG. Can be detected even 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 minimum becomes the top dead center. If used, CPU 19
Can automatically detect the top dead center. For example, the volume value V or the resonance frequency ratio (f ₂ / f ₁ ) ^{2 in the} expression (5)
(Note, may be f ₂ / f ₁₎ is output to the external monitor (for example, a display device 21), the operator may be rotated with a crankshaft 7a to the monitor value is minimized while watching this. FIG. 8 is a flowchart illustrating the measurement procedure of the present embodiment described above. In FIG. 8, first, the number n of cylinders is input from the keyboard 23 in step S1. Steps S5 and S5
The measurement at the angle i in 6 shall be repeated at least twice. Further, in step S8, step S4, S5, S7 in the obtained V _T, i, V _i the bottom dead center from the volume V _B, connecting rod length L, to calculate the crank radius r and the cylinder bore cross-sectional area A. In this embodiment,
Although the displacement W was obtained from the measured value of one cylinder and the preset number of cylinders n by Expression (6), if the above measurement is performed for all the cylinders, the displacement W can be more accurately obtained. Can be. That is, the stroke volume (V
_B− V _T ) is obtained, and the sum thereof is the displacement. In that case,
If the volume measuring means is prepared by the number of cylinders and the measurement of each cylinder is performed at the same time, it is not necessary to remove and transfer the volume measuring means for each cylinder, so that the measurement can be performed in a shorter time. Note that the volume measuring means, the method of measuring the resonance frequency, and the volume calculating formula are not limited to those described in the present embodiment.

[0016] Next, the embodiments described heretofore, the measured value from equation (1) of the crank angle of at least three locations determined unknowns type, and requests the volume V _B at the bottom dead center. However, when it is not necessary to perform measurement with such high accuracy, the relational expression of V-θ in the expression (1) can be expressed as the following expression (10) by approximating the relational expression of V-θ with a sine curve. V = ｛− (V _B −V _T ) / 2｝ cos θ + (V _B + V _T ) / 2 (Equation 10) Therefore, the volume Vi at the crank angle _i is expressed by (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 the equation (11), V _T , V _i and i are obtained as measured values. , The volume V _B at the bottom dead center is obtained from the equation (11) as in the following equation (12). _{V B = {2V i -V T} (1 + cosi)} / (1-cosi) ... ( Equation 12) as described above, when was approximated by the sine curve (number 1) relationship of the V-theta of the measurement result of the crank angle i of the volume V _T and one position in the upper dead point, that it is possible to calculate the combustion chamber volume V _B at the bottom dead center by the measurement results of the total two places. Further, as another example, there is a method of estimating the volume V _B at the bottom dead center in the following manner. That is, generally, the change in the combustion chamber volume near the bottom dead center is smaller than the change in the crank angle θ, and the ratio of the connecting rod length L to the crank radius r of a normal engine is L / r = 3.5 to 4 , The measurement of the volume V is performed at two points of the top dead center and the crank angle θ ≒ ± h / 2 closest to the bottom dead center in the valve fully closed section h. / from the relationship, such as r can be estimated volume V _B at the bottom dead center. The measurement and calculation of the bottom dead center volume V _B is not limited to this embodiment.

Next, a second embodiment of the present invention will be described. In this embodiment, the rotation angle θ of the crankshaft 7a is
Is measured instead of measuring the displacement of the piston 6, and the displacement W, the compression ratio ε, and the like are obtained based on the measured value. The piston displacement measuring means for measuring the displacement of the piston 6 is, for example, a measuring instrument 24 such as a dial gauge as shown in FIG. 5, and measures the displacement of the piston 6 directly from the piston crown surface 6a. is there. Note that the measuring device 24 may be a displacement meter or a distance meter using an ultrasonic wave, a laser, or the like. Assuming that the movement 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 in FIG. Therefore, the piston movement amount St and the volume V of the combustion chamber 8
Is a proportional relationship as shown in FIG. In FIG. 9, the angle on the horizontal axis indicates the top dead center as θ = 0 [de
g], and the piston movement amount St on the vertical axis has a value of 0 at the top dead center. Here the movement amount i.e. the stroke s of the bottom dead center, the piston movement of at any crank angle j and p, the combustion chamber volume at this time is V _p.

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

Next, another embodiment relating to a 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 the ignition plug is machined at the connection portion of the sensor head 9, and is screwed into the ignition plug hole 14 for connection. The present embodiment is for preparing for measurement more easily 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 in and 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. However, there is no problem if the above-described calibration is performed in a state including the gap.

Next, another embodiment of the volume measuring means will be described. FIG. 12 is a sectional view of a second embodiment of the volume measuring means. In this embodiment, the cavity of the combustion chamber 8 and the acoustic tube 13
Constitute a Helmholtz resonator, and the sound source 11 is arranged outside the resonator to vibrate. In this embodiment,
In the embodiment of FIG. 1, this is a preferred example when the volume V ′ of the cavity 12 cannot be made sufficiently large as compared with the volume V of the combustion chamber 8. One end of the acoustic tube 13 is opened to the atmosphere through a hole 26. Since a large sound source having a higher reproduction sound pressure than 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) Further, the resonance is generated in the acoustic pipe 13, the resonance frequency f ₂ is represented by the following equation (17). f ₂ = c / 2d (and an integer multiple thereof) (Equation 17) If the sound velocity c is eliminated from the above (Equation 16) and (Equation 17), the volume becomes as shown in the following (Equation 18) V is required. V = k (f ₂ / f ₁ ) ² (Equation 18) where k = dS / π ² Equations (16) and (17) are theoretical equations under ideal conditions. If the equation (18) obtained from these equations is used, there is a possibility that a measurement error occurs. Therefore, the actual calculation formula may be an approximate formula using a constant k 'experimentally obtained by performing a calibration experiment using a container having a known volume and dimensions.

The other constructions and operations are the same as in the first embodiment. Next, FIG. 13 is a sectional view of a third embodiment of the volume measuring means. This embodiment is effective when the sound source 11 cannot be arranged at the position as shown in FIG. This extends the acoustic tube 13 to the outside of the engine 1,
Further, by disposing the sound source 11 outside thereof, the sensor head 9 can be mounted without being restricted by the size of the sound source 11 or the like.
Is designed to be designed. Others are shown in FIG.
The description is omitted because it is the same as that of the embodiment. In the embodiment shown in FIGS. 12 and 13, the holes 26 opened to the atmosphere are used.
The reason is that resonance is favorably generated even when the sound source 11 having a large equivalent capacitance is used.
Further, since the hole 26 opened to the atmosphere is provided in this manner, it is not necessary to provide the air introduction pipe 30 of FIG.

Next, a description will be given of an embodiment in which it is determined whether or not the measured value of the engine to be measured is within a predetermined reference range based on the measurement result. In the embodiments described above, the measurement result is simply displayed on the display device 21. In this embodiment, the design value of the engine to be measured or the like is stored in advance in the memory 20 as a reference value, or is input from the keyboard 23, and the reference value and the measured value are compared. If the comparison result is within a predetermined allowable range such as a preset design standard or the like, it is judged as acceptable, and if not, it is determined that there is an abnormality in the engine to be measured, and the details of the abnormality are output to the display device 21. It is configured to be displayed. With this configuration, it is possible to easily determine whether the engine conforms to the set standard, is illegally modified, or the like. These operations may be programmed so that the CPU 19 automatically performs the operations using the measurement results.
Further, the content of the comparison, the reference value, and the like 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 volume of the combustion chamber is measured at a plurality of piston positions in the range where the intake / exhaust valve is in the fully closed state, and the combustion at the bottom dead center is determined from those values. The configuration that calculates the room volume has the effect of enabling accurate and easy measurement of engine specifications such as actual displacement and actual compression ratio in the engine assembled state, which could not be measured conventionally. Can be Therefore, by using the present invention, not only can it be used for engine experiments, research, inspections at factory lines, etc., but also it can easily inspect illegally modified vehicles or imported vehicles at the time of vehicle inspection, which was difficult in the past. Becomes possible.

[Brief description of the drawings]

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

FIG. 2 is a block diagram illustrating a configuration of a calculation unit.

FIG. 3 is a perspective view showing a mounted state of the rotation angle detecting 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 of 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 a relationship between a combustion chamber volume V and a crank angle θ.

FIG. 8 is a flowchart illustrating a measurement procedure according to the first embodiment.

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

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

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

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

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

[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 spark 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 ... Measurement device 25 ... Surface 26 ... Hole 30 ... Air introduction pipe

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Claims (5)

(57) [Claims] 1. When the engine is assembled,
Volume measurement means for measuring the volume of the combustion chamber of the engine; rotation angle measurement means for measuring the rotation angle of the crankshaft; input of the measurement results of the volume measurement means and the rotation angle measurement means; Using a plurality of measured values of the volume of the combustion chamber measured at a plurality of different rotation angles in the range of the rotation angle of the crankshaft, the displacement of the engine, the compression ratio, the stroke, the connecting rod length, and the crank An engine measuring device comprising: a calculating means for obtaining at least one of a radius and a cylinder / bore diameter. 2. The engine measuring device according to claim 1, wherein said rotation angle measuring means measures a rotation angle based on a rotation time of the crankshaft rotating at a constant speed. 3. When the engine is assembled,
Volume measuring means for measuring the volume of the combustion chamber of the engine; piston moving amount measuring means for measuring the piston moving amount; input of the measurement results of the volume measuring means and the piston moving amount measuring means; Using a plurality of measured values of the combustion chamber volume measured at a plurality of different piston positions in the range of the piston position that is, 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 obtaining at least one of a cylinder bore diameter and at least one of the following. 4. The volume measuring means is an acoustic measuring means utilizing a Helmholtz resonator, and is mounted via a spark plug hole of an engine. The engine measuring device according to any one of the above. 5. A judging means for judging whether or not a measured value of an engine as an object to be measured is a value within a predetermined reference range based on a calculation result of the calculating means, and displaying the judgment result. The engine measuring device according to any one of claims 1 to 4, further comprising: display means.