JPH0220664Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to an experimental engine for measuring the frictional force and thrust force acting on the piston of an internal combustion engine.

Prior Art As a conventional measurement engine, for example, a cylindrical liner is arranged in a hole formed in a cylinder block, a piston is slidably provided in this cylindrical liner, and the lower end of the liner There is a known configuration in which the liner and the bottom of the hole are connected by a sensor, and this sensor measures the force in the axial direction of the liner (Proceedings of the 4th Joint Symposium on Internal Combustion Engines ('84-1) P.301, Furuhama/Sasaki). In this configuration, the sensor is a load cell consisting of a piezoelectric element, and measures the force in the axial direction of the liner, that is, the frictional force received by the piston, as a force acting in the compression direction of this sensor, and the side pressure of the liner, that is, the thrust force, is measured on the outer circumference of the liner. It is received by a pin provided in the

Problems that the invention aims to solve: Since the conventional measuring engine described above cannot measure thrust force, it is not possible to experimentally determine the relationship between piston friction force and thrust force.
There is a problem in that sufficient data necessary for reducing frictional force cannot be obtained. In addition, the support rigidity of the liner is relatively small and the natural frequency of the measurement engine is approximately 1KHz, so it is impossible to measure due to the large noise in the high rotation range, and it is only possible to measure conditions below approximately 1400 rpm. Furthermore, since a frictional force acts between the pin receiving the thrust force and the outer peripheral surface of the liner, there is a problem in that the frictional force of the piston is measured to be smaller than the actual value.

Means for Solving the Problems In order to solve the above problems, the measuring engine of the present invention has a cylindrical liner disposed in the hole formed in the cylinder block, and a piston is slid inside the cylindrical liner. The inner wall surface of the hole and the outer circumferential surface of the cylindrical liner are connected substantially only by a sensor, and the sensor is configured to act at least on a first force acting in the axial direction of the cylindrical liner; A second force acting in a direction perpendicular to the direction of the first force and parallel to the swinging surface of the connecting rod can be measured.

Function: Since the cylindrical liner is disposed in the hole formed in the cylinder block, and the piston is slidably disposed within the cylindrical liner, the relative movement of the piston with respect to the cylindrical liner causes The resulting frictional force tends to move the tubular liner in its axial direction. Since the cylindrical liner and the bore of the cylinder block are connected substantially only by the sensor, the first axial force due to the frictional force is transmitted to the cylinder block through the sensor. The size is measured by applying a minute displacement in the axial direction to the sensor.

In addition, a force that acts in a direction perpendicular to the direction of the first force and parallel to the oscillating surface of the connecting rod, that is, a thrust force, is similarly transmitted to the cylinder block through the sensor. It is measured by applying a minute displacement.

Example The present invention will be explained below with reference to illustrated embodiments.

FIG. 1 shows a measurement engine according to an embodiment of the present invention. This measurement engine is for measuring piston friction force and thrust force while actually burning the air-fuel mixture. In this diagram,
The cylinder block has a flat plate part 10 and a cylindrical part 11, and a cylindrical liner 13 is disposed within a hole 12 formed inside the cylindrical part 11. This cylindrical liner 13 is supported by a side plate 14 fixed to the outside of the cylindrical portion 11 of the cylinder block and a three-way force sensor 16 mounted in a horizontal hole 15 passing through the side wall of the cylindrical portion 11. That is, the outer circumferential surface of the cylindrical liner 13 is spaced apart from the inner wall surface of the hole in the cylindrical portion 11, and the sensor 16 is substantially separated from the inner wall surface of the hole in the cylindrical portion 11.
The cylindrical liner 13 is connected to the cylindrical part 1 by a chisel.
It is possible to make a minute displacement with respect to 1.

Cylinder bore 1 which is an internal hole of cylindrical liner 13
A piston 20 is slidably supported at 7. The piston 20 is connected to a connecting rod 22 via a piston pin 21, and the connecting rod 22 is slidably supported by a crankshaft 23. Therefore, when the crankshaft 23 rotates, the connecting rod 22 swings, which causes the piston 20 to move up and down within the cylinder bore 17 and exert a frictional force and a thrust force on the cylindrical liner 13.

The sensor 16 is constructed by laminating and superposing a large number of disks made of piezoelectric elements, and is provided near one end of the cylindrical liner 13 in the axial direction and near the other end.
In each of these parts, they are arranged at intervals of approximately 90° in the circumferential direction. FIG. 2 shows the cylindrical liner 1 of the sensor 16.
3, and the axial direction, that is, the compression direction of the piezoelectric element of each sensor 16 coincides with the left-right direction in the figure. In other words, the axial direction of each sensor 16 lies within a plane parallel to the plane in which the connecting rod 22 swings. Therefore, the sensor 16 detects the force that acts on the cylindrical liner 13 when the piston 20 moves up and down within the cylindrical liner 13, that is, the piston friction force that acts in the axial direction (Y direction) of the cylindrical liner 13. , and a thrust force acting in a direction (Z direction) parallel to a plane perpendicular to this axial direction (swing plane of the connecting rod 22). That is, the sensor 16 detects thrust force by displacement in the compression direction, and detects friction force by displacement in the shear direction. The sensor 16 also detects a force in a direction perpendicular to both the frictional force and the thrust force, that is, a force in a direction perpendicular to the page of FIG. It is not used as data for analysis.

A flange 30 is formed at the upper end of the cylindrical portion 11, and a seal plate 31 is fixed onto the flange 30. The cylinder head 32 is placed on the upper surface of the seal plate 31, and a combustion chamber 33 is defined by the lower surface of the cylinder head 32, the inner peripheral surface of the seal plate 31, the cylinder bore 17, and the top surface of the piston 20. The seal plate 31 has an annular shape, and its outer circumference matches the outer circumference of the flange 30, while its inner circumference is located inward from the inner circumference of the cylindrical liner 13. That is, the inner peripheral portion of the seal plate 31 protrudes inside the cylindrical liner 13, and the upper end portion of the cylindrical liner 13 fits into an annular groove 34 formed on the lower surface of the seal plate 31. The upper end of the cylindrical liner 13 has an annular groove 3
A sealing O-ring 35 is provided on the inner wall surface of the combustion chamber 33 so that the inside of the combustion chamber 33 is airtightly sealed off from the outside.

An intake port 40 and an exhaust port 41 are formed in the cylinder head 32, and these ports 40, 4
1 are provided with intake and exhaust valves 42 and 43, respectively. The intake valve 42 opens and closes as a rocker arm 44 disposed above the cylinder head 32 swings, and the rocker arm 44 is rockingly driven by a cam follower 46 and a push rod 47 that move up and down as the cam 45 rotates. The cam 45 is the side plate 1
It is housed in a cam case 48 provided outside of 4. Similarly, the exhaust valve 43 opens and closes as the rocker arm 53 swings, and the rocker arm 53 swings as the cam follower 51 and push rod 52 move up and down, which move up and down due to the rotation of the cam 50 housed in the cam case 49.

As mentioned above, the sensor 16 is located at the top of FIG.
The friction force and thrust force acting on the cylindrical liner 13 are measured by a total of eight sensors 16. Figure 3 shows 8 sensors 1
An overview of the measurement system including 6 is shown below. In this figure, all lead wires 60 extending from the sensor 16 to the left side are connected to a charge amplifier 61, and each sensor 1
The output signals of No. 6 are amplified, added together, and output. This output signal is
3 in the axial direction (Y direction in FIG. 1), that is, frictional force, and indicates a shearing force acting on the sensor 16.
On the other hand, the lead wires extending from the sensor 16 to the right side of the figure are connected to the lead wires 62 connected to the four sensors 16 on the left side of the cylindrical liner 13 and to the four sensors 16 on the right side of the cylindrical liner 13. It consists of a lead wire 63. The lead wire 62 is connected to a charge amplifier 64 and an inverting differential amplifier 65.
3 is connected to a charge amplifier 66 and a differential amplifier 67. The outputs of these amplifiers 65 and 67 are taken out from one lead wire 68, so the output signals obtained from the leads 62 and 63 of each sensor 16 are amplified and summed and output from the lead wire 68. be done. In this case, the outputs of the four sensors 16 on the left side of FIG.
The polarity can be reversed by This is because the compression directions of the right sensor and the left sensor are opposite, and the positive and negative polarities are matched. The output signal from lead 68 is the lateral (Z direction in FIG. 1) or thrust force on tubular liner 13 and is indicative of the compressive force acting on sensor 16.

Since this embodiment has the above configuration, the frictional force and thrust force acting on the cylindrical liner 13 are measured in the following manner.

When combustion pressure acts on the combustion chamber 33, the piston 20 is pressed downward, and the connecting rod 22
The crankshaft 23 rotates via. At this time, the cylindrical liner 13 is pushed down along the Y direction by the frictional force received from the piston 20, and also pushed in the Z direction by the thrust force. Therefore, an electric charge is generated in the sensor 16 in an amount proportional to the magnitude of the force in the Y direction and the force in the Z direction.
1, 64, 66, etc., and output to an oscilloscope or the like.

FIGS. 4 and 5 show examples of graphs of measurement results. Figure 4 shows the measurement results when the opening degree of the throttle valve is changed, where a shows the combustion pressure, b shows the friction force, and c shows the thrust force, and the solid line R
indicates when firing is performed with the throttle valve fully open; dashed line S indicates when firing is performed with the throttle valve opened 1/4; and dashed line T indicates when firing is performed with the throttle valve opened 1/4. Each case is shown below. On the other hand, Figure 5 shows the measurement results when changing the ignition timing, where a is the combustion pressure,
b indicates the frictional force, and c indicates the thrust force.The solid line R indicates the ignition timing when the crank angle is 20 degrees before the top dead center, and the dashed line S indicates the dashed line when the ignition timing is the crank angle 10 degrees before the top dead center. T indicates the case where the ignition timing is at top dead center.

In this way, by simultaneously measuring the frictional force and thrust force acting on the cylindrical liner 13, the relationship between these two forces can be analyzed, and the results of this analysis can be used to obtain a method for reducing the frictional force. Can be used as data. The results of this analysis can also be used to determine the optimal piston offset to minimize piston slap.

Furthermore, in this embodiment, the cylindrical liner 13 is substantially supported by only eight sensors 16, and since there is no member other than these sensors 16 on which frictional force acts, it is not possible to accurately measure the frictional force. It is possible.

Furthermore, since the outer peripheral surface of the cylindrical liner 13 is supported by eight sensors 16, the support rigidity is greater than that of conventional devices, and therefore measurements can be made up to a high rotation range. FIG. 6 shows the results of frequency analysis of vibrations when the device of this embodiment is subjected to hammering. As can be seen from this figure, the natural frequency of the device of this embodiment is about 3.5 KHz, which is much larger than the conventional case where frictional force is measured by compression acting on a sensor. As a result, according to the device of this embodiment, it is possible to measure rotation speeds up to about 4900 rpm.

FIG. 7 shows another embodiment of the invention. In this embodiment, the cylindrical liner 13 is supported by a sensor 16 only on the outer peripheral surface on the left side of the figure with respect to the cylindrical portion 11 of the cylinder head, and no sensor is provided on the outer peripheral surface on the right side. Also, intake and exhaust ports 40 and 41 are not formed in the cylinder head,
The upper part of the combustion chamber 33 is closed by a seal plate 31, so that firing cannot be performed, and the measurement of frictional force and thrust force is performed by motoring. The other configurations are basically the same as the embodiment shown in FIG. 1, and the explanation thereof will be omitted.

It goes without saying that the present invention can also be applied to a two-stroke engine.

Further, although the sensor is not limited to one made of a piezoelectric element, it is preferable to select the mounting orientation of the sensor in order to minimize the mutual influence (crosstalk) between pressure and shear force.

Effects of the invention As described above, according to the invention, the frictional force and thrust force acting on the liner can be measured simultaneously, and the natural frequency can be increased to increase the measurable rotational speed.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing one embodiment of the present invention;
The figure is a plan view showing the arrangement of the sensor with respect to the cylindrical liner, Fig. 3 is a circuit diagram showing the measurement system, Figs. 4 and 5 show examples of measurement results, and Fig. 4 shows the opening degree of the throttle valve. , a graph showing the influence of ignition timing on combustion pressure, frictional force, and thrust force in the combustion chamber; Figure 5 is a graph showing the influence of ignition timing on combustion pressure, frictional force, and thrust force; Figure 6 is a graph showing the influence of ignition timing on combustion pressure, frictional force, and thrust force; FIG. 7 is a graph showing the results of frequency analysis when the embodiment device is subjected to hammering. FIG. 7 is a sectional view showing another embodiment of the present invention. 12...hole, 13...cylindrical liner, 16...sensor, 20...piston.

Claims (1)

[Claims for Utility Model Registration] 1. A cylindrical liner is disposed in a hole formed in a cylinder block, and a piston is slidably provided in this cylindrical liner, and the inner wall surface of the hole and the cylindrical liner is connected to the outer peripheral surface of the connecting rod by substantially only a sensor, and the sensor is connected to at least a first force acting in the axial direction of the cylindrical liner and a direction perpendicular to the direction of the first force and of the connecting rod. The second actuator acts in a direction parallel to the oscillating surface.
A measurement engine characterized by being able to measure the force of. 2. The sensor is provided at a first axial position and a second axial position on the outer circumferential surface of the cylindrical liner, and is spaced at intervals of approximately 90° in the circumferential direction at each of these positions. 2. The measuring engine according to claim 1, wherein the measuring engine is installed with its axis parallel to the swinging surface of the connecting rod and oriented in the horizontal direction. 3. Utility model registration claim 1, characterized in that the above-mentioned sensor is formed by laminating and polymerizing piezoelectric elements.
Measurement engine described in section.