JPH11108801A - Measuring apparatus for frictional force of internal-combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely measure the magnitude of a frictional force acting between the piston and the cylinder liner of an internal-combustion engine by a simple means by preventing an influence due to the pressure of a combustion chamber. SOLUTION: A circumferential groove 33 is formed at the outside of a part near the upper end part of a cylinder liner 3 and in an upper part from the position of the upper dead center of a top ring 82 at a piston 8, and a thin wall part is formed. In addition, strain gages 70a, 70b as the detecting means of the expansion and contraction amount in the direction of the central axis of the Thin wall part are pasted on the bottom face of the groove 33 which is substantially parallel to the central axis line of the cylinder liner 3. Even when the pressure of a combustion chamber 16 acts on the surface of a flange 31 at the cylinder liner 3, a frictional force acts substantially on the bottom face of the groove 33. As a result, as different from a conventional apparatus in which strain gages are pasted both on the surface and the rear surface of the flange 31 as a deformable part, an error due to the influence of the pressure of the combustion chamber is not generated in the detection value of the frictional force.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an apparatus for measuring a frictional force acting between a piston and a cylinder of an internal combustion engine.

[0002]

2. Description of the Related Art In an internal combustion engine, in order to measure the magnitude of a frictional force acting between a piston and a cylinder, a cylinder liner is not firmly fixed to a cylinder block.
Elastically supported by special support means so that it can move slightly in the direction of the center axis of the cylinder liner,
When the piston slides up and down in the cylinder liner, the cylinder liner moves with the piston by frictional force, and the amount of displacement that the cylinder liner moves vertically by elastically deforming the support means is detected. 2. Description of the Related Art There is known an apparatus which measures the magnitude of an applied frictional force by directly detecting the amount of elastic deformation of a supporting means or by detecting the amount of elastic deformation of a supporting means.

FIG. 2 shows a configuration of a main part of such a conventional example. In FIG. 2, 1 is a cylinder block, 2 is a cylinder head, 3 is a cylinder liner made of steel, and an annular flange 31 projecting to the outer periphery is integrally formed at the upper end of the cylinder liner 3. Reference numeral 4 denotes a gasket for sealing, and reference numeral 5 denotes an annular packing 5 for sealing. The strain gauge 7 in the form of a thin film for detecting frictional force
One of them is attached to the upper and lower surfaces of the deformable portion 31a which is not sandwiched between the cylinder block 1 and the cylinder head 2. Reference numeral 8 denotes a piston that slides in the cylinder liner 3 in a vertical direction, 15 denotes a cooling water jacket, and 16 denotes a combustion chamber.

When the piston 8 slides up and down in the cylinder liner 3, a frictional force F acts on the cylinder liner 3, so that the deformable portion 31a of the flange 31 is changed in accordance with the direction and the magnitude of the frictional force F. To bend and deform. The amount of deformation causes expansion and contraction of the resistance wire constituting the thin film strain gauge 7 attached to the upper and lower surfaces of the deformable portion 31a. , The amount of bending deformation of the deformable portion 31a, and hence the frictional force F
Can be measured.

However, in the configuration of the first conventional example shown in FIG. 2, the pressure P in the combustion chamber 16 acts on the upper end surface of the cylinder liner 3 and the upper surface of the deformable portion 31a of the flange 31. Therefore, the deformation amount of the deformable portion 31a is
Since the sum of the amount of deformation caused by the frictional force F and the amount of deformation caused by the action of the combustion chamber pressure P is substantially obtained, only the magnitude of the frictional force F can be accurately determined from the electric resistance value of the strain gauge 7. It cannot be measured. As the force for deforming the deformable portion 31a, besides the frictional force F and the combustion chamber pressure P, there is also a force due to the inertial force accompanying the movement of the cylinder liner 3, but the value of the inertial force is relatively small. It can be ignored.

In order to eliminate the problem of the first conventional example shown in FIG. 2, that is, the error of the measured value of the frictional force F due to the combustion chamber pressure P acting on the upper end surface of the cylinder liner 3 and the upper surface of the flange 31, In the second conventional example shown in FIG. 3, the cylinder liner 3 is extended upward to provide an extension 3a which enters into an annular groove 2a formed on the lower surface of the cylinder head 2, and the extension 3a An O-ring 9 is formed between the inner surface and the wall surface of the annular groove 2a of the cylinder head 2 facing the inner surface.
The combustion chamber pressure P in the combustion chamber 16 does not act on the upper end surface of the extended cylinder liner 3 or the upper surface of the flange 31.

In order to solve the same problem, in a third conventional example shown in FIG. 4, an extension 3a is provided by extending the upper end of a cylinder liner 3 to a level higher than the lower surface of a cylinder head 2. An annular seal groove 32 is formed on the inner surface of the extension 3a. The upper and lower side surfaces 32a and 32b of the seal groove 32 have the same projected area in the vertical direction. An annular groove (or notch) 2 a is provided on the lower surface of the cylinder head 2, and an adapter 40 fitted in the annular groove 2 a is connected to the cylinder block 1 by bolts 50.
Attached to. The adapter 40 is provided with an annular groove 40a, in which an extension 3 of the cylinder liner 3 is provided.
a is fitted. On the inner side surface of the annular groove 40a, a surface 40b as a step is formed symmetrically with the upper surface 32a of the seal groove 32 of the cylinder liner 3, and the upper surface 32a
Also, it supports an O-ring 9 for sealing.

A spacer 41 having an appropriate thickness is sandwiched between the lower end surface of the adapter 40 and the surface of the step portion of the cylinder block 1 opposed thereto, and the tightening force of a bolt 50 for compressing the spacer 41 is provided. Is adjusted so that the O-ring 9 is connected to the upper surface 32 a of the cylinder liner 3 and the adapter 4.
0 is evenly brought into contact with the surface 40b. In the third conventional example, the frictional force to be measured is detected by a load cell 37 attached between a flange 35 formed at the lower end of the cylinder liner 3 and the cylinder block 1 by a bolt 36 connecting them. Is done.

In the third conventional example, the pressure in the combustion chamber 16 acts on the O-ring 9 to generate a force to push it upward, thereby forming a seal around the combustion chamber 16. About half of the upward force acting on 9 is applied to the upper surface 32 a of the seal groove 32 of the cylinder liner 3. At the same time, the pressure of the combustion chamber 16 also acts on the lower surface 32b of the seal groove 32 to generate a downward force of the same magnitude, so that forces of the same magnitude and opposite directions are canceled out, The force pushing the cylinder liner 3 upward or downward by the combustion chamber pressure disappears. Therefore, substantially only the frictional force due to the sliding of the piston 8 acts on the cylinder liner 3.

[0010]

As described above, the problem in the first conventional example shown in FIG. 2, that is, the error in the measured value of the frictional force due to the pressure in the combustion chamber is the second problem shown in FIG. Or the third conventional example shown in FIG. 4, but all of these solutions require a complicated sealing device at the joint between the upper end of the cylinder liner and the cylinder head or cylinder block. Because of the necessity of a configuration, this increases the difficulty of processing, disassembly, assembly, adjustment, and the like, and raises another problem that costs increase.

The present invention solves all of the above-mentioned problems in the prior art, and eliminates the influence of the combustion chamber pressure on the measured value with a simple structure, and measures substantially only the frictional force. It is an object of the present invention to provide an improved frictional force measuring device that can perform the following.

[0012]

Means for Solving the Problems In order to solve the above problems, the means described in claim 1 can be adopted. According to this means, the circumferential groove is formed on the outer surface near the upper end of the cylinder liner, and above the top dead center position of the piston top ring, and the thin portion of the cylinder liner is formed. Detecting means for detecting the amount of expansion and contraction in the direction of the center axis of the cylinder liner is provided on the bottom surface of the circumferential groove. Since the circumferential groove where the detection means is provided is above the top dead center position of the piston top ring, the bottom of the groove is not affected by the pressure of the combustion chamber. It becomes possible to measure.

By providing the detecting means on the bottom surface of the groove in the direction in which the thrust force perpendicular to the crankshaft acts, the main part of the frictional force acting between the cylinder liner and the piston corresponding to the wear amount of the piston and the piston Can be detected. In this case, if a plurality of detecting means are provided to face each other so as to form a pair, detection accuracy is improved.

The circumferential groove provided with the detecting means can be formed as an annular groove surrounding the entire circumference of the cylinder liner. Thereby, since the detection means can be provided not only on the bottom surface in the direction in which the thrust force acts but also on the remaining bottom surface, not only the main part of the frictional force,
It is possible to detect the sum of the frictional forces over the entire circumference of the cylinder liner. The sum of the frictional forces corresponds to the friction loss of the internal combustion engine.

As a preferable detecting means, a strain gauge which outputs an electric resistance value is preferably used. By bridging a plurality of strain gauges, it is possible to measure frictional force with high accuracy.

According to the present invention, the cylinder liner can be fixedly supported on the cylinder block on the upper end side and can be supported on the lower end side so as to be movable in the direction of the central axis. With this configuration, the thin portion formed by the circumferential groove of the cylinder liner on which the detection means is provided freely expands and contracts in the direction of the central axis due to the frictional force, so that the frictional force can be accurately measured by a large amount of expansion and contraction. Can be. According to the configuration of the present invention, only the frictional force can be measured without being affected by the combustion chamber pressure, so that the flange formed at the upper end of the cylinder liner forms a pressure receiving surface or a variable portion that receives the combustion chamber pressure. The friction force can be measured without any problem.

[0017]

FIG. 1 shows a friction force measuring device for an internal combustion engine according to a first embodiment of the present invention. Also in the embodiment of the present invention, the same reference numerals are given to the same components as those in the conventional example described above with reference to FIGS. That is, also in FIG. 1, 1 is a cylinder block,
Reference numeral 2 denotes a cylinder head mounted on the upper portion of the cylinder block 1, and 3 denotes a steel cylinder liner supported inside the cylinder block 1. An annular flange 31 projecting to the outer periphery is integrally formed at the upper end of the cylinder liner 3. Is formed. 4 is a sealing gasket, 5 is an annular sealing gasket 5, and a stepped portion 1 on the upper part of the cylinder block 1.
1 and the flange 31 of the cylinder liner 3
Is sandwiched between the gasket 4 on the side of the cylinder head 2 and the cylinder block 1 and the cylinder head 2 at the portion supporting the upper end of the cylinder liner 3.
The seal between is easily achieved.

A seal land 12 projecting inward is provided below the cylinder block 1, and a circular hole 13 having an inner diameter slightly larger than the outer diameter of the cylinder liner 3 is formed in the seal land 12. The lower portion of the cylinder liner 3 is inserted into the hole 13, and the cooling water jacket 15 is sealed by an O-ring 6 mounted in a groove 14 formed in the circular hole 13. In the figure, 8
Is a piston that slides vertically in the cylinder liner 3,
Reference numeral 16 denotes a combustion chamber, and 81 denotes a piston pin of the piston 8.

As a feature of the present invention, when the piston 8 is located at the top dead center as shown in FIGS. 1A and 1B below the flange 31, In a position that is further higher than the top ring 82 that is the uppermost of the two or three piston rings,
An annular groove 33 is provided on the outside of the cylinder liner 3, whereby the thickness of the cylinder liner 3 is reduced only at the groove 33, so that the cylinder liner 3 can easily expand and contract in the direction of the central axis. Thin film strain gauges 70a and 70b capable of detecting the amount of expansion and contraction in the direction of the central axis, that is, in the vertical direction, are attached to the bottom surface of the groove 33.

In the case of the first embodiment shown in FIGS. 1A and 1B, the inner diameter of the cylinder liner 3 and the inner diameter of the combustion chamber 16 are the same, and the inner diameter of the gasket 4 is slightly larger than them. Therefore, the area of the upper surface of the flange 31 at the upper end of the cylinder liner 3 that receives the pressure of the combustion chamber in the combustion chamber 16 is small, and the amount of deformation of the flange 31 due to the pressure of the combustion chamber is relatively small. Therefore, before describing the operation of the first embodiment, as a more characteristic example, the configuration, operation, and effects of the second embodiment shown in FIG. I do. The operation and effect of the first embodiment correspond to part of that of the second embodiment.

FIG. 5 shows a frictional force measuring apparatus according to a second embodiment of the present invention, in which only an essential part is shown. As in the first conventional example shown in FIG.
Is provided with a larger pressure receiving area than in the first embodiment and a large deformable portion 31a of the flange 31 on the upper surface of the first embodiment. In this case, if the strain gauges 7 are attached to the upper and lower surfaces of the flange 31, the same problem as in the above-described first conventional example should occur, but in the second embodiment of the present invention, the first embodiment will be described. Similarly to the case of the above, an annular groove 33 is formed outside the cylinder liner 3 at a position near the upper end of the cylinder liner 3 and above the top dead center position of the top ring 82 of the piston 8, A strain gauge 70 (for example, 70a or 70b in FIG. 1) is attached to a thin portion on the bottom surface of the groove 33.

The force acting in the vicinity of the groove 33 of the cylinder liner 3 substantially includes the combustion chamber pressure P in the combustion chamber 16, the elasticity R of the deformable portion 31 a of the flange 31, and the force acting between the piston 8 and the cylinder liner 3. The frictional force F acting between them and the inertial force I of vibration (not shown). Since the groove 33 to which the strain gauge 70 is attached is formed in the upper part of the cylinder liner 3 immediately below the flange 31, even if the piston 8 is at the top dead center (the dashed line in FIG. 5), the strain gauge 70 is 8 above the top ring 82. Therefore, the frictional force F between the cylinder liner 3 and the piston 8 always acts on the portion below the groove 33 of the cylinder liner 3.

On the other hand, the pressure P in the combustion chamber 16 and the elasticity R of the flange 31 always act above the groove 33. Further, since the inertial force I of the vibration is sufficiently smaller than the frictional force F, the force acting on the position below the groove 33 of the cylinder liner 3 is substantially only the frictional force F. Therefore, groove 3
The thin portion on the bottom surface of the cylinder liner 3 expands and contracts in the direction of the central axis of the cylinder liner 3 substantially only by the frictional force F without being affected by the combustion chamber pressure P. The amount of deformation (the amount of expansion and contraction) can be directly measured by the gauge 70, and only the magnitude of the frictional force F can be accurately detected without being affected by the combustion chamber pressure P from the amount of deformation.

As is clear from the operation and effect of the second embodiment, in the first embodiment shown in FIG. 1, the pressure in the combustion chamber at the upper end of the cylinder liner 3 and the flange 31 is larger than that in the second embodiment. Since the pressure receiving area of P is small, the bending deformation of the flange 31 due to the pressure of the combustion chamber is smaller than in the case of the second embodiment. Moreover, the point that the strain gauge 70 is attached to the bottom surface of the annular groove 33 formed outside the position close to the upper end of the cylinder liner 3 is the same as that of the second embodiment, so that the friction of the first embodiment is different. The force measuring device can accurately detect only the frictional force F acting between the cylinder liner 3 and the piston 8 by the strain gauge 70 without being affected by the combustion chamber pressure P.

In the first and second embodiments, the position where the strain gauge 70 is attached on the bottom surface of the annular groove 33 formed in the cylinder liner 3 is not particularly described. In the embodiment, as is apparent from FIG. 1, the cylinder liner 3 and the piston 8, which are considered to mainly exert a frictional force, are located at opposing positions in the direction in which the thrust force acts (the direction perpendicular to the crankshaft). A pair of strain gauges 70a and 70b are attached.

However, when the strain gauge 70 is attached only to a part of the bottom surface of the annular groove 33, the frictional force transmitted by the specific portion of the bottom surface of the groove 33 to which the strain gauge 70 is attached. However, it is not possible to measure the value of the sum of the frictional forces considered to be distributed and transmitted to the bottom surface of the entire circumference of the groove 33 with some deviation. Accordingly, when a relatively short strain gauge 70 is attached to only a part of the bottom surface of the annular groove 33 and the friction force is measured, as in the direction in which the thrust force acts, the value of the detected friction force is Or, it corresponds to the wear amount of the cylinder liner 3, but does not always correspond to the magnitude of the friction loss of the internal combustion engine.

The third embodiment of the present invention shown in FIGS.
In the embodiment, the entire circumference is divided into several parts, and the long and short strain gauges 70 are attached to them so that the strain gauges 70 are arranged over substantially the entire bottom surface of the annular groove 33. Thus, the sum of the frictional forces acting on the cylinder liner 3 and the value of the frictional force at a specific portion can be measured together from the plurality of detected values.

That is, as shown in FIG. 6, of the bottom surface of the annular groove 33 formed on the outer side near the upper end of the cylinder liner 3, an opposing portion where a thrust force in a direction perpendicular to the crankshaft 100 acts. A pair of relatively short thin film strain gauges 70a and 70b are attached to the
A pair of relatively long thin film strain gauges 70c and 70d are attached so as to oppose each other so as to cover substantially the entire bottom surface of the third.

The structure of each of the strain gauges 70 is the same as the strain gauges 70c and 70d illustrated in FIG. 7, and an electric resistance wire 73 is provided on a gauge base 72 made of a strip-shaped electric insulator.
Are arranged in a zigzag shape, and when the bottom surface of the groove 33 of the cylinder liner 3 expands and contracts due to a frictional force acting below the groove 33, the gauge base 72 attached to the bottom surface expands and contracts in the direction of the arrow. When the diameter of the portion of the resistance wire 73 in the direction of the arrow changes, the value of the electrical resistance between both ends 73a and 73b of the resistance wire 73 changes. The strain gauges 70a and 70b have the same structure, but have a smaller horizontal length than the strain gauges 70c and 70d.

The thin film strain gauges 70a, 70b and 70
In the third embodiment, the signals output by c and 70d as the value of the electric resistance are processed by the bridge circuit 74 illustrated in FIG. That is, the pair of short strain gauges 70a and 70b are inserted at opposing positions in the upper bridge circuit portion 75, and the other pair of long strain gauges 70c and 70d are positioned at opposing positions in the lower bridge circuit portion 76. Inserted. In FIG. 8, reference numerals 70e, 70f, 70g, and 70h denote dummy resistors, and 71a, 71b, 71c, and 71d.
Denotes a terminal, and 77 denotes a constant-voltage power supply.

Due to the frictional force acting between the cylinder liner 3 and the piston 8, the relatively short strain gauges 70 a and 70 b attached mainly to the position where the thrust force perpendicular to the crankshaft 100 acts are applied to the cylinder liner 3.
Greatly expands and contracts in the direction of the central axis. As a result, the terminal 7
A voltage corresponding to the expansion and contraction is output between 1a and 71b. Since this voltage is a signal of a portion where the frictional force acts in a concentrated manner, it corresponds to the wear amount of the cylinder liner 3 or the piston 8.

The frictional force transmitted from the bottom surface of the groove 33 by a portion other than the position where the thrust force acts is also applied to the terminal 71 by the relatively long strain gauges 70c and 70d.
It is detected as an output voltage between c and 71d. Therefore, terminals 71a and 71b are provided by a computer (not shown) or the like.
Output voltage between the terminals 71c and 71d,
By multiplying and adding a coefficient corresponding to the area of each strain gauge 70, the magnitude of the total frictional force acting between the cylinder liner 3 and the piston 8 can be obtained. This value corresponds to the friction loss of the internal combustion engine as described above.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional front view showing a first embodiment of a frictional force measuring device according to the present invention, wherein FIG. 1 (a) shows the entire configuration and FIG. .

FIG. 2 is a longitudinal sectional front view showing an enlarged main part of a first conventional example.

FIG. 3 is a longitudinal sectional front view showing an enlarged main part of a second conventional example.

FIG. 4 is a longitudinal sectional front view showing an enlarged main part of a third conventional example.

FIG. 5 is an enlarged longitudinal sectional front view showing a main part of a second embodiment of the present invention.

FIG. 6 is a perspective view conceptually showing a third embodiment of the present invention.

FIG. 7 is a plan view illustrating one of the strain gauges used in the present invention.

FIG. 8 is an electric circuit diagram showing a bridge circuit used in a third embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Cylinder block 2 ... Cylinder head 3 ... Cylinder liner 7 ... Strain gauge 8 ... Piston 16 ... Combustion chamber 31 ... Flange 31a ... Variable part 33 ... Annular groove 82 ... Top ring 70, 70a-70d ... Strain gauge F ... Friction force P: Combustion chamber pressure R: Elasticity

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Daisuke Nakagawa 14 Iwatani, Shimowasumi-cho, Nishio City, Aichi Prefecture Inside the Japan Automobile Parts Research Institute (72) Inventor Shinji Kato 1st Toyota Town, Toyota-shi, Aichi Prefecture Toyota Auto Inside the car company

Claims (8)

[Claims] 1. A circumferential groove is formed on an outer surface near an upper end portion of a cylinder liner and above a top dead center position of a top ring of a piston reciprocating inside the cylinder liner. And detecting the amount of expansion and contraction of the thin portion of the cylinder liner that forms the bottom surface of the groove in the direction of the center axis on the bottom surface of the circumferential groove substantially parallel to the center axis of the cylinder liner. A friction force measuring device for an internal combustion engine, comprising a detecting unit. 2. The frictional force measuring device according to claim 1, wherein the detecting means is provided on a bottom surface of the groove in a direction in which a thrust force perpendicular to a crankshaft acts. 3. The frictional force measuring device according to claim 1, wherein a plurality of the detecting means are provided so as to form a pair around the cylinder liner. 4. The frictional force measuring device according to claim 1, wherein the circumferential groove is formed as an annular groove surrounding the entire circumference of the cylinder liner. 5. The detection means is provided not only on the bottom surface in the direction in which the thrust force acts but also on the remaining bottom surface in the bottom surface of an annular groove surrounding the entire circumference of the cylinder liner. The frictional force measuring device according to claim 4, wherein the frictional force measuring device is provided over the entire circumference of the annular groove. 6. The frictional force measuring device according to claim 1, wherein said detecting means comprises a strain gauge for outputting an electric resistance value. 7. The cylinder liner is fixedly supported on a cylinder block on an upper end side thereof.
7. The frictional force measuring device according to claim 1, wherein a lower end portion is supported so as to be movable in a direction of a central axis. 8. The friction force according to claim 1, wherein a flange formed at an upper end portion of the cylinder liner has a pressure receiving surface receiving a combustion chamber pressure and a deformable portion. Measuring device.