JPH0531253Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a cylinder maximum pressure detection device for an internal combustion engine.

[Conventional technology]

In engines with variable nozzle area superchargers and variable injection timing injection pumps, it is important to know the maximum in-cylinder pressure. As one of them, for example, a cylinder maximum pressure detector has been proposed in Japanese Patent Application No. 59-206181. This application discloses a method of minimizing the fuel consumption rate by controlling the nozzle area of the supercharger to an appropriate value by processing the detected values of maximum cylinder pressure, shaft torque, and scavenging pressure using a computer.

[The problem that the idea attempts to solve]

In such conventional devices, since the gas pressure and gas temperature inside the cylinder are high, the detection part of the highest pressure detector is inevitably exposed to high temperature and pressure, so its durability is insufficient and its lifespan is short. Moreover, there was a problem in that sufficient measurement accuracy could not be obtained because the temperature of the detection section changed.

The purpose of the present invention is to provide a cylinder maximum pressure detection device that eliminates the problems of the conventional device, ensures the durability of the measuring device, maintains a sufficient lifespan, and is also satisfactory in terms of accuracy. .

[Means to solve the problem]

The cylinder maximum pressure detection device according to the present invention includes a scavenging pressure detector, an engine load detector, an injection timing detector, a memory in which the relationship between the load, injection timing, and additional pressure is set, and the detection device The computer has a calculation device that performs calculations by inputting the detection signal from the detector and the additional pressure in the memory device, and calculates the compression pressure calculated based on the output signal from the scavenging pressure detector and the calculated value from the experiment. An additional pressure set in a predetermined memory is selected in correspondence with detected values of engine load and injection timing, and the maximum cylinder pressure is determined by adding the additional pressure to the calculated compression pressure. It is characterized by

[Effect]

The maximum cylinder pressure detection device of the present invention has sufficient durability and can determine the maximum cylinder pressure using highly accurate scavenging pressure and engine load and injection timing detectors. It can be used in various monitoring devices and control devices instead of the short-life in-cylinder maximum pressure detector like conventional devices.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 3. FIG. 1 is a block diagram of the same device. In the figure, 1 is an engine having a variable nozzle area supercharger and a variable injection timing injection pump, 2 is a load detector, 3 is a scavenging pressure detector, 4 is an injection timing detector, and 100 is a computer. The computer 100 includes analog to digital converters 102 to 104, a digital to analog converter 101, a cylinder pressure calculator 105, and a memory 10.
It consists of 6.

Next, the operation of the above embodiment will be explained.

The load detector 2 detects the load substituted by pump rack, rotation speed, engine output, etc. among the engine operating state quantities, the scavenging pressure detector 3 detects the scavenging pressure, and the injection timing detector 4 detects the variable injection timing injection pump. Detects fuel injection timing.
Various detected values are converted into analog values within the computer 100. The calculator 105 theoretically calculates the cylinder compression pressure Pc from the scavenging pressure Ps using the following equation (1), and selects the additional pressure ΔP corresponding to the detected engine load L and injection timing θ from the memory 106. , calculate the cylinder maximum pressure Pmax using the following equation (2).

That is, Pc=Psε ^K ...(1) Pmax=Pc+ΔP...(2) Here, ε and K are the compression ratio and compression index determined by the engine condition, and the memory 106 is the experimental data such as actual machine operation data. The results show the relationships shown in Figure 3.

Maximum cylinder pressure in the computer 100
To explain in more detail how to calculate Pmax, the scavenging pressure Ps detected by the scavenging pressure detector 3
Based on the equation (1), the computing unit 105 calculates the compression pressure Pc.

In the memory 106, the relationship ΔP=f(L, θ) between the additional pressure ΔP, load L, and injection timing θ based on experimental data such as engine operating data is set as shown in FIG. has been done.

The detected value of the engine load L from the load detector 2 and the detected value of the injection timing θ from the injection timing detector 4 are converted from analog to digital converter 10.
2, 104 and is input to the arithmetic unit 105.

(4) The calculator 105 selects the additional pressure ΔP corresponding to the detected values of the load L and the injection timing θ from the setting data shown in FIG.
Calculate the cylinder maximum pressure Pmax using the formula.

The device can also be applied to engines without variable nozzle area superchargers and variable timing injection pumps.
It can also be applied when using an analog computer. At this time, converters 101 to 104 are unnecessary.

[Effect of idea]

Since the present invention is constructed as described above, it is not necessary to use a detection means under high temperature and high pressure like the conventional ones, and it can be used to detect engine load, scavenging pressure, and injection timing under high temperature and high pressure. The maximum in-cylinder pressure can be calculated with high accuracy by simply using the detected value by the detection means that does not require the use of additional pressure and by introducing additional pressure that has accumulated operational data.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the maximum cylinder pressure detection device according to the present invention, and Fig. 2 shows the load L, nozzle area A, and scavenging pressure of an engine with a variable nozzle area supercharger.
A diagram showing the relationship between Ps and FIG. 3 is a diagram showing experimental results between load L, injection timing θ, and additional pressure ΔP of an engine having a variable injection timing fuel injection pump. 1...Engine, 2...Load detector, 3...Scavenging pressure detector, 4...Injection timing detector, 10
0...Computer, 105...Arithmetic unit, 106
...Memory device, Ps...Scavenging pressure, L...Engine load,
θ...Injection timing, ΔP...Additional pressure.

Claims (1)

[Scope of utility model claims] A load detector for detecting the load of the engine, a scavenging pressure detector for detecting the scavenging air pressure of the engine, an injection timing detector for detecting the injection timing of the fuel injection pump, and an additional pressure adapted to the load and injection timing. A storage device set based on experimental data of the engine, and detection signals of the load, scavenging pressure, and injection timing are input, and the compression pressure is calculated from the detected value of the scavenging pressure, and the load and injection timing are detected. and an arithmetic unit that selects an additional pressure corresponding to the value from the setting data in the storage device and adds it to the calculated value of the compression pressure to calculate the maximum cylinder pressure. Detection device.