CN2378728Y - Pressure gage for air cylinder of diesel engine - Google Patents

Abstract

A diesel engine cylinder pressure gauge mainly solves the disadvantages of low measurement accuracy and poor reliability in the prior art. It includes a meter body and a sensor, a circuit board is arranged in the meter body, and a charge amplifier, a low-pass filter, a peak hold device, a selector switch, an A/D converter, an LCD display, and an average circuit are arranged on it. The sensor is a ring piezoelectric sensor, which is connected to the input of the charge amplifier. The utility model can measure the highest explosion pressure and the average pressure of the gas in the cylinder of the diesel engine.

Description

Diesel engine cylinder pressure gauge

The utility model relates to a device for measuring the highest explosion pressure and the average pressure of gas in a cylinder of a diesel engine.

At present, the main equipment for measuring the pressure in the cylinder of large and medium-sized diesel engines relies on a mechanical maximum pressure gauge, a spring indicator, and a measurement system composed of a water-cooled diaphragm piezoelectric ceramic pressure sensor or C-sensor and a single-chip microcomputer. However, they have the following disadvantages: the one-way valve of the mechanical maximum pressure gauge does not work normally under the action of high-temperature gas, which makes the reading error of the mechanical maximum pressure gauge in practice too large, which can only be used for qualitative analysis, and cannot be used continuously at high temperatures. work; the spring dynamometer cannot directly measure the average pressure, and the spring stiffness is easy to drop; in recent years, an intelligent instrument for measuring the pressure change in the diesel engine cylinder has appeared, using a diaphragm piezoelectric ceramic pressure sensor, due to the short fatigue life of the diaphragm , and the high price of this type of instrument is not conducive to popularization; although the C-sensor solves the problem of short fatigue life of the diaphragm piezoelectric ceramic pressure sensor diaphragm, the C-sensor is too large (the outer diameter of the circumference is greater than 60mm) , the natural frequency is low (according to our calculation, the C-sensor has a pair of natural frequencies that have a great influence on the measurement around 300HZ), which affects the measurement accuracy, especially the measurement accuracy of the in-cylinder process of medium and high speed diesel engines, and is not easy to install on the diesel engine.

The purpose of the utility model is to provide a device for dynamically measuring the highest explosion pressure and the average pressure of gas in a cylinder of a diesel engine with high measurement accuracy and strong reliability.

The purpose of this utility model is achieved in that it includes a meter body and a sensor, and a circuit board is arranged in the meter body, on which a charge amplifier, a low-pass filter, a peak value holder, a selector switch, an A/D converter, The LCD display and the mean value circuit are characterized in that the above-mentioned sensor is a ring-shaped piezoelectric sensor, which is connected with the input terminal of the charge amplifier.

In the above-mentioned piezoelectric sensor, there is an annular sensor body 7, one side of which clamps a pair of piezoelectric ceramic sensitive elements 8 by two screws, and a heart electrode 9 is arranged between the two sensitive elements 8. An insulating sheath 10 is arranged on the periphery, and a terminal 11 is provided on the side or end of the sensor body 7, and the heart electrode 9 is connected with the input terminal of the charge amplifier in the meter through the terminal 11 with a wire.

The above-mentioned piezoelectric sensor and other components constitute a sensor assembly, wherein the sensor 6 is arranged on the radiator 2, the center of the radiator 2 is provided with a gas channel, and the bottom of the radiator 2 is threaded and a hollow mandrel 3, the mandrel 3 is provided with a threaded joint 5 connected with the explosion detection valve, the upper part of the threaded joint 5 is provided with a handwheel 4, and the upper end of the sensor 6 is connected with the input terminal of the charge amplifier through a signal line.

The utility model has the advantages of high measurement precision and strong reliability. It adopts the diesel engine cylinder pressure gauge composed of annular pressure sensor and secondary instrument in terms of high temperature resistance, temperature drift and fatigue life, etc. And for one, the measurement value is accurate, the operation is convenient, it can work for a long time, and the cost is low. It is an upgraded product of the mechanical maximum pressure gauge and the mechanical average pressure gauge.

Below in conjunction with accompanying drawing, the utility model is further described.

Fig. 1 is a schematic diagram of two appearance connection modes of the present invention.

Fig. 2 is a structural schematic diagram of the sensor assembly in the utility model.

FIG. 3 is a structural schematic diagram of the annular piezoelectric pressure sensor 6 in FIG. 2 .

Fig. 4 is a circuit block diagram in the utility model.

Fig. 5 is a schematic diagram of the structure of the body panel of the utility model.

Fig. 6 is a circuit diagram of the utility model.

The structure shown in the accompanying drawings is an embodiment of the present utility model. Each circuit in the circuit block diagram is a prior art, and is an existing conventional circuit, which can be selected from the circuit design manual at that time, so it will not be repeated here. The unique feature of this utility model is that it adopts an annular piezoelectric pressure ceramic sensor, which together with related components constitutes a sensor assembly, which consists of an insulating sheath 1, a radiator 2, a hollow mandrel 3, and a heat-insulating handwheel 4 , a threaded joint 5 connected to the explosion detection valve, and an annular piezoelectric pressure sensor 6. The annular piezoelectric pressure sensor 6 is composed of an annular sensor body 7 , a sensitive element 8 , a heart electrode 9 , an insulating sheath 10 of a heart wire, and a terminal post 11 . The gas pressure in the cylinder of the diesel engine acts on the inner wall of the annular pressure sensor body 7, and the annular piezoelectric sensor 6 converts the gas pressure into a charge signal, which is transmitted to the secondary instrument composed of various circuits and panel components through wires, and is installed on the annular sensor body 7. A portion of material is cut off or an unloading groove is provided at the corresponding outer cylindrical surface of the piezoelectric sensitive element 8 . The binding posts can be arranged on the outer cylindrical surface of the annular sensor body 7, arranged radially along the annular sensor body, or arranged on the end face of the annular sensor body 7, arranged axially, and the sensitive elements are installed with prestress. The panel 12 of the utility model is provided with components such as an LCD display 13, a power switch 14, a selector switch 15, a self-check button 6, a data latch button 17, a reset button 18, and the like. The secondary instrument composed of a circuit and a casing panel can be integrated with the pressure sensor assembly (as shown in the left figure of Figure 1), or it can be divided into two parts, and the two are connected by a signal line (as shown in the right figure of Figure 1). When the secondary instrument and the pressure sensor assembly are integrated, vibration isolation and heat insulation components (such as wire rope vibration isolators, etc.) can be installed between the secondary instrument and the sensor assembly.

Claims (3)

1, a kind of Cylinder Pressure of Diesel Engine table, include table body and sensor, be provided with circuit board in the table body, which is provided with charge amplifier, low-pass filter, peak-holding circuit, selector switch, A/D converter, LCD display, average circuit, it is characterized in that: above-mentioned said sensor is a kind of ring piezoelectric formula sensor, and it and charge amplifier input end join.

2, cylinder of diesel engine according to claim 1 pressure side table, it is characterized in that: in the above-mentioned said piezoelectric transducer, a loop sensor body (7) is arranged, the one side is by two a pair of piezoelectric sensors of screw clamping (8), be provided with heart electrode (9) between two sensitive elements (8), be provided with insulating sheath (10) in sensitive element (8) periphery, sensor body (7) side or end face are established binding post (11), and heart electrode (9) joins by the input end of binding post (11) with the interior charge amplifier of lead and table body.

3, Cylinder Pressure of Diesel Engine table according to claim 1 and 2, it is characterized in that: above-mentioned said piezoelectric transducer and other parts constitute a sensor module, wherein, sensor (6) is arranged on the heating radiator (2), the center of heating radiator (2) is provided with gas passage, the below of heating radiator (2) joins by the axle (3) of screw thread and a hollow, axle (3) is provided with a threaded connector (5) that is connected with the quick-fried valve of inspection, the top of threaded connector (5) is provided with a handwheel (4), and the upper end of sensor (6) joins by signal wire and charge amplifier input end.

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