JPS6236166B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a torque detector that detects the effective torque of an internal combustion engine based on the internal cylinder pressure of the engine.

Conventional torque detectors for internal combustion engines are of the type that measures the transmitted torque by installing the detector in the torque transmission shaft that connects the engine and the load. Resistance wire strain gauge type torque detectors, photoelectric type Various types of torque detectors, such as torque detectors and magnetostrictive tube torque detectors, have been put into practical use. Each of the above-mentioned torque detectors includes a detection section for detecting twist of the torque transmission shaft and a measurement circuit section. For example, in a resistance wire strain gauge type torque detector having a slip ring in the torque detecting section, there are problems such as vibration of the contacts of the slip ring and wear of the contacts due to vibration of the vehicle body. Furthermore, photoelectric torque meters and magnetostrictive tube torque meters that do not have contact parts such as slip rings have the problem of being economically undesirable because they must be redesigned every time the torque transmission axis changes. Therefore, there is a need for a torque detector that can be easily attached to an engine and is inexpensive.

The present invention satisfies this requirement by integrating a signal representing the internal cylinder pressure of the engine from the bottom dead center position of the piston to the top dead center position, and also from the top dead center position to the bottom dead center position, and integrates the signal representing the internal cylinder pressure of the engine. The purpose of the present invention is to provide a torque detector that is inexpensive, highly accurate, and easy to install, by having a configuration that calculates the effective torque of an engine from the cylinder volume, the number of cylinders, and a predetermined torque calculation constant. It is.

The present invention will be explained below with reference to an embodiment shown in the drawings. FIG. 1 is a diagram showing the overall block configuration, in which 101 is a pressure detector that detects the pressure inside the cylinder of the internal combustion engine, and 102 and 103 are the pistons of this cylinder at the top dead center position and the bottom dead center position. It is an angle detector that detects that. 201 is an electrical calculation circuit that calculates the effective torque of the engine;
04 is a pressure signal amplifier that amplifies the signal from the pressure detector 101, and 105 is this pressure signal amplifier 10.
This is a signal inverter that inverts the pressure signal voltage of 4.
107 also integrates the pressure signal voltage from the bottom dead center position to the top dead center position, and from the top dead center position to the bottom dead center position, and calculates the effective torque of the engine from the difference between the two integral values. This is an integral calculation circuit that holds a value for a certain period of time. 106 is a logic circuit that controls the integration period from the bottom dead center position to the top dead center position and the integration period from the top dead center position to the bottom dead center position.

FIG. 2 is a cross-sectional view showing how the pressure detector 101 is attached to the engine and its structure.
is inserted between the cylinder head 1 and the spark plug 2 and tightened. This pressure detector 101 includes a piezoelectric element 3 that is polarized by elastic strain and generates a voltage at both ends, and electrode plates 4 and 5 are bonded to both ends of the piezoelectric element 3. The outer circumferences of the electrode plates 4 and 5 are covered with circular plates 6 and 7, and the space between them is filled with an adhesive 8. Further, 9 and 10 are lead wires for taking out signals. Next, this pressure detector 10
The operation of No. 1 will be described. The pressure sensor 101 receives an initial load when the spark plug 2 is installed in the cylinder head. When the pressure inside the cylinder of the engine increases, the spark plug 2 is pressed from inside, so the load on the pressure detector 101 is reduced.
The load applied to the piezoelectric element 3 in the pressure detector 101 is also reduced. Therefore, a voltage proportional to the cylinder pressure is generated in the piezoelectric element 3.

FIG. 3 is a detailed electrical circuit diagram of this embodiment,
101 is a pressure detector, and its output signal is input to a pressure signal amplifier 104. This is a well-known operational amplifier 2
The output of this operational amplifier 21 enters a signal inverter 105. Operational amplifiers 22 and 2
3 have the same gain, so each output becomes an output voltage that is symmetrical with respect to OV. Angle detectors 102 and 103 for detecting the top dead center and bottom dead center positions of the piston are mounted on a disk that rotates at the same time as the camshaft. Cut slits corresponding to the dead center position and top dead center position,
The structure has a light emitting element (not shown) and a light receiving element facing each other, and each time the piston passes through the bottom dead center position and the top dead center position, the light passes through the slit and the light receiving element conducts. Detect dead center position. 106 is a logic circuit and an angle detector 10
The top dead center angle detection signal representing the top dead center position from 2 is inputted to the set terminal of the RS flip-flop 37 through the inverter 34 and stored. Further, the bottom dead center angle detection signal representing the bottom dead center position from the angle detector 103 is transmitted to the inverter 35 and the OR gate 3.
6, enters the reset terminal of the R-S flip-flop 37, and is stored. Resistor 32, capacitor 3
3 is for initial setting of the R-S flip-flop when the power is turned on. The outputs E and D of the inverters 34 and 35 are at the "1" level at the top dead center position and the bottom dead center position (Fig. 4e, d), and the output F of the D flip-flop 38 is at the low level as shown in Fig. 4f. It operates to maintain the "1" level from dead center _T1 to top dead center _T2 , and the output G of the R-S flip-flop 37 is maintained at the "1" level from top dead center _T2 to bottom dead center T2, as shown in FIG. It operates to maintain the “1” level for ₃ hours. Further, the Q output of the monostable match vibrator 39 is maintained at the "1" level for a certain period of time ( _until time _T4 ) from the bottom dead center T3, as shown in FIG. 4i. Also, as shown in Figure 4h, this output is “1”.
An AND gate 40 is used to hold the "1" level signal for a period from when the level changes to "0" level until the next bottom dead center _T1 . The integral calculation circuit 107 includes an analog switch 24 and an operational amplifier 25, and the analog switch 24 includes an R-S flip-flop 37, a D flip-flop 38,
The switches 24a, 24b, and 24c are controlled by the output signals G, F, and H of the AND gate 40, and when these signals are at the "1" level, the switches 24a, 24b, and 24c are rendered conductive. The operational amplifier 25 constitutes an integrator from a resistor 26 and a capacitor 28, and the resistor 27 is a resistor for discharging the capacitor 28. In addition, 3
0,31 is the power supply.

Next, the operation of the above configuration will be described. generally 4
The effective torque TE of a stroke cycle engine is TE = 1/2π x 200Vs・Z・pm, where Vs is the cylinder volume, Z is the number of cylinders, and Pm is the average effective pressure, and the effective torque TE can be detected from the average effective pressure Pm. Become. Here, by multiplying the average effective pressure Pm by the cylinder volume Vs and the number of cylinders Z,
The amount of work for one engine cycle (two rotations) is calculated,
Also, the amount of work in one cycle of the engine is equal to the product of effective torque TE and rotational distance 2 x 2π x 100 (cm), so Vs・Z・Pm=2×2π×100, therefore, TE=1/2π× It becomes 100Vs・Z・Pm. Note that the average effective pressure Pm is approximately the cylinder pressure P ₁ (θ) from top dead center to bottom dead center in the explosion stroke and the cylinder pressure from bottom dead center to top dead center in the compression stroke.
It is obtained from the average value of P ₂ (θ), and Pm=k( ₀ P ₁
(θ)dθ− ⁰ P ₂ (θ)dθ), k: constant.
In other words, this average effective pressure Pm is the sum of the integral value S ₁ of the pressure signal proportional to the cylinder pressure from the bottom dead center position to the top dead center position and the integral value S ₂ from the top dead center position to the bottom dead center position. It can be determined from the difference. Therefore, when the engine is operated and the cylinder equipped with the pressure detector 101 undergoes a compression or explosion stroke, a voltage Vp(t) proportional to the cylinder pressure is applied to the pressure signal amplifier 104 as shown in FIG. 4a. Occurs at output A. The output B of the signal inverter 105 has - as shown in FIG. 4b.
Vp(t) is generated. Then, the control signal of the analog switch 24a between the bottom dead center _T1 and the top dead center _T2 becomes "1" level, the switch 24a becomes conductive, and the integration of the output voltage Vp(t) of the operational amplifier 22 is started. Now the resistance value of resistor 26 is R ohm,
Assuming that the capacitance of the capacitor 28 is C farad,
The voltage V ₁ of the output C of the operational amplifier 25 becomes V ₁ =-1/RC∫ ^T2 _T1 Vp(t)dt=-S ₁ /RC. However, S ₁ = ∫
^T2 _T1 Vp(t)dt. Next, from top dead center T ₂ to bottom dead center
Switch 24b of analog switch 24 between T ₃
Only the output voltage of the operational amplifier 23 -Vp is conductive.
(t) is integrated, and the voltage Vo of the output C of the operational amplifier 25 is Vo=V ₁ -1/RC∫ ^T3 _T2 {-Vp(t)}dt=-S ₁
+S ₂ /RC. That is, the effective torque TE becomes TE=K・(S ₂ −S ₁ )=K・RCVo. However, S ₂ =∫ ^T3 _T2 {−Vp(t)}dt, K is a constant. Further, while the output I of the monostable multivibrator 39 is at the "1" level, this voltage Vo is held in the capacitor 28, and when the output H of the AND gate 40 reaches the "1" level, the switch 24C of the analog switch 24 is turned on and the capacitor is turned on. The charge at 28 is discharged through resistor 29 and initialized. That is, by reading the voltage of the output C of the operational amplifier 25 when the output I of the monostable multivibrator 39 is at the "1" level, the effective torque of the engine can be detected for each rotation as shown in FIG. 4c.

Although the above embodiment shows the case where the pressure detector 101 for detecting the internal cylinder pressure of the engine is inserted between the plug and the cylinder head, it can be similarly detected by inserting it between the cylinder head and the cylinder tightening bolt. That is clear.

As described above, the present invention detects the internal cylinder pressure of the engine using a pressure detector, and also uses an angle detector to detect whether the piston of this cylinder is at the top dead center position or the bottom dead center position. Integrate the signal representing the cylinder pressure from the signal from the piston from the bottom dead center position to the top dead center position, and from this top dead center position to the next bottom dead center position, and calculate the value of both integrals and the cylinder volume, By adopting a configuration that calculates the effective torque of the engine from the number of cylinders and a predetermined torque calculation constant, it is possible to provide a torque detector that can accurately detect the effective torque of the engine for each rotation, and is inexpensive and easy to install. It has this excellent effect.

[Brief explanation of the drawing]

Fig. 1 is a block configuration diagram showing one embodiment of the present invention, Fig. 2 is a sectional view showing the structure of the pressure detector in Fig. 1 and how it is attached to the engine, and Fig. 3 is a block diagram showing an embodiment of the present invention.
The detailed electric circuit diagram shown in the figure, and FIG. 4 is a signal waveform diagram of each part of FIG. 3. 101... Pressure detector, 102, 103... Angle detector, 107... Integral computing circuit forming the main part of the electrical computing circuit, 201... Electric computing circuit.

Claims (1)

[Claims] 1. A pressure detector that detects the pressure inside the cylinder of the internal combustion engine, an angle detector that detects whether the piston of this cylinder is at the top dead center or bottom dead center position, and a From both detection signals,
The signal representing the cylinder pressure is integrated from the bottom dead center position of the piston to the top dead center position, and from this top dead center position to the next bottom dead center position, and the difference between the two integral values and the cylinder volume of the engine are calculated. , the number of cylinders, and an electrical calculation circuit that calculates the effective torque of the internal combustion engine from the product of a predetermined torque calculation constant.