JP2017067495A - Method for measuring amount of thermal deformation of inner surface of peripheral wall of cylinder of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to measure the amount of thermal deformation of am inner surface of a cylinder bore when an internal combustion engine is operated at high rotational speed or at high load.SOLUTION: In a cylinder block, strain gauges are mounted on outer surfaces of peripheral walls of cylinders, which face a water jacket surrounding the cylinders, and temperature sensors for measuring temperatures of the peripheral walls of the cylinders are installed, so that an internal combustion engine is operated. While the amount of stain of the peripheral walls of the cylinders is measured by the strain gauges, the amount of thermal expansion is obtained by measuring the temperatures of the peripheral walls of the cylinders by the temperature sensors.SELECTED DRAWING: Figure 1

Description

  The present invention relates to measurement of the amount of thermal deformation of an inner surface of a peripheral wall of a cylinder of an internal combustion engine mounted on a vehicle or the like.

  During operation of the internal combustion engine, the shape of the bore inner surface of the cylinder undergoes thermal deformation due to temperature rise. The relationship between the inner shape of the cylinder and the outer shape of the piston and the piston ring affects the mechanical loss accompanying the reciprocating motion of the piston of the internal combustion engine and the consumption amount of the lubricating oil. Measuring the degree of deformation of the inner surface of the bore of the cylinder during operation of the internal combustion engine is considered useful for achieving both reduction of mechanical loss and suppression of lubricating oil consumption.

  As disclosed in the following patent documents, conventionally, a plurality of gap sensors are embedded in the outer periphery of the piston (a gap sensor is attached to a low expansion material such as an invar alloy provided on the piston), and each gap sensor is provided. The amount of thermal deformation of the bore inner surface was measured by measuring the distance from the cylinder to the bore inner surface of the cylinder. Signal transmission / reception methods between the gap sensor and the measuring device (or computer) include a wired link method, a wireless telemeter method, a logger method, and the like.

  However, with such a conventional method, it is practically difficult to measure the amount of thermal deformation of the bore inner surface when the internal combustion engine is operated at a high rotation speed or a high load. This is because, in the high rotation or high load operation region, the heat resistance limit of the gap sensor, the G mechanism resistance limit of the link mechanism for signal transmission or the telemeter, and the allowable rotation speed limit are exceeded.

  In particular, since the consumption of the lubricating oil of the internal combustion engine increases in a high rotation or high load region, it is important to evaluate the amount of thermal deformation of the bore inner surface in the high rotation or high load region.

JP 2010-149562 A

  An object of the present invention is to make it possible to measure the amount of thermal deformation of the bore inner surface of a cylinder in a high rotation or high load range.

  The method for measuring the amount of thermal deformation of the inner surface of the cylinder peripheral wall of the internal combustion engine according to the present invention includes attaching a strain gauge to the outer surface of the cylinder peripheral wall facing the water jacket surrounding the cylinder in the cylinder block, and Operating the internal combustion engine with a temperature sensor that measures the temperature, measuring the amount of strain on the cylinder's peripheral wall via a strain gauge, and measuring the temperature of the cylinder's peripheral wall via a temperature sensor to measure the amount of thermal expansion It is characterized by knowing.

  According to the present invention, it is possible to measure the amount of thermal deformation of the bore inner surface of a cylinder in a high rotation or high load range.

The top view which shows the cylinder block of the internal combustion engine in one Embodiment of this invention, and the installation location of a strain gauge and a temperature sensor. The top view which shows the installation location of the cylinder block of the internal combustion engine in the same embodiment, and the strain gauge inside and outside the surrounding wall of a cylinder.

  Hereinafter, a method for measuring the amount of thermal deformation of the bore inner surface of the cylinder 2 according to an embodiment of the present invention will be described with reference to the drawings.

  In order to carry out this measurement method, as shown in FIG. 1, strain gauges 4 are provided at various locations on the outer surface of the peripheral wall of each cylinder 2 facing the water jacket 3 surrounding the cylinder 2 in the cylinder block 1 of the internal combustion engine. Affix. At the same time, a thermocouple 5 is installed as a temperature sensor for measuring the temperature of a portion of the peripheral wall of the cylinder 2 near the portion where the strain gauge 4 is attached. Then, in this state, the internal combustion engine is operated, and while measuring the amount of strain at various locations on the peripheral wall of the cylinder 2 via the strain gauge 4, the temperature at various locations on the peripheral wall of the cylinder 2 is measured via the thermocouple 5 Know the amount of thermal expansion at the location. Incidentally, FIGS. 1 and 2 show an example of an in-line three-cylinder engine.

  The strain gauge 4 is present on the outer surface side of the peripheral wall of the cylinder 2 and does not hinder the reciprocating motion of the piston during operation of the internal combustion engine. In addition, since it is arranged in the water jacket 3 filled with cooling water during operation of the internal combustion engine, the problem of heat resistance does not occur.

  The strain gauge 4 directly measures the amount of strain on the outer surface of the peripheral wall of the cylinder 2, but as a result of intensive research by the inventors of the present invention, the amount of thermal deformation of the outer surface of the peripheral wall of the cylinder 2 and the heat of the inner surface. The amount of deformation is proportional, and regardless of the temperature conditions of the peripheral wall, the amount of thermal deformation of the outer surface and the amount of thermal deformation of the inner surface are substantially equal, that is, the amount of thermal deformation of the outer surface of the peripheral wall and the amount of thermal deformation of the inner surface. Was found to have a 1: 1 relationship. Therefore, the amount of strain at each location on the outer surface side of the peripheral wall measured by each strain gauge 4 can be substituted for the amount of strain at each location on the inner surface side of the peripheral wall.

  As described above, as shown in FIG. 2, the strain gauges 4 and 6 are arranged facing the outer surface side and the inner surface side of the peripheral wall of the cylinder 2, respectively, and the strain amount measured by the strain gauge 4 on the outer surface side is as follows. A comparison is made with the amount of strain measured by the strain gauge 6 on the inner surface side. At that time, the cylinder block 1 is heated with high-temperature water, high-temperature oil, hot air, or the like, thereby raising the temperature of the peripheral wall of the cylinder 2 to a state close to that during actual operation. For example, hot air is blown into the cylinder 2 while filling the water jacket 3 with high-temperature water or high-temperature oil. This is because it is difficult to perform the actual operation of the internal combustion engine because the strain gauge 6 on the inner surface side interferes with the piston that reciprocates in the cylinder 2.

  When measuring the amount of strain on the inner surface of the peripheral wall of the cylinder 2 during operation of the internal combustion engine, strain gauges 4 and 6 are attached in advance as shown in FIG. And the correlation between the amount of strain at each location on the inner surface side. Then, the internal combustion engine is operated with the strain gauge 4 attached only on the outer surface side of the peripheral wall of the cylinder 2 (with the strain gauge 6 on the inner surface side of the peripheral wall removed), that is, the fuel is burned in the cylinder 2 While moving the piston, the strain gauge 4 measures the amount of strain on the outer surface side of the peripheral wall, and uses the correlation obtained in advance to determine the strain amount on the inner surface side of the peripheral wall. Convert.

  The strain amount measured through the strain gauge 4 represents the strain deformation amount along the radial direction of the peripheral wall of the cylinder 2. On the other hand, it is difficult for the strain gauge 4 to detect the amount of thermal expansion along the circumferential direction of the peripheral wall of the cylinder 2. The temperature of each part of the peripheral wall of the cylinder 2 is measured by the thermocouple 5 in order to know the amount of thermal expansion along the circumferential direction of each part of the peripheral wall. The correlation between the temperature measured via the thermocouple 5 and the amount of thermal expansion along the circumferential direction of the peripheral wall is found in advance from the constituent material of the peripheral wall. Therefore, the temperature of each place measured by the thermocouple 5 can be converted into the amount of thermal expansion along the circumferential direction of each place on the peripheral wall using the known correlation.

  In addition, the amount of strain deformation along the radial direction of each part of the peripheral wall of the cylinder 2 (measured by the strain gauge 4) is geometrically converted into the amount of deformation along the peripheral direction of the peripheral wall, and this is converted into the thermocouple 5 The thermal expansion amount along the circumferential direction of the corresponding portion of the peripheral wall (based on the temperature measured by the above) may be added together.

  In an internal combustion engine in which a plurality of cylinders 2 are arranged in series, each cylinder 2 is orthogonal to the direction in which the cylinders 2 are arranged, that is, the direction in which the intake port and the exhaust port of each cylinder 2 face each other. And deformed so as to be elliptical in plan view (or cross-sectional view). Compared to this, since the amount of strain along the direction in which the plurality of cylinders 2 are arranged is very small, as shown in FIG. 1 and FIG. It is not always necessary to attach strain gauges 4 and 6 and measure the amount of strain.

  The above-described measurement of the amount of strain and the amount of thermal expansion of each part of the peripheral wall of the cylinder 2 can be performed while changing the temperature of the peripheral wall of the cylinder 2 in various ways. In other words, the amount of strain and the amount of thermal expansion at each location on the peripheral wall can be measured for each temperature of the peripheral wall, for example, for each value of various cooling water temperatures within a range of 25 ° C. to 110 ° C.

  The method for measuring the amount of thermal deformation of the bore inner surface of the cylinder 2 according to the present embodiment includes attaching a strain gauge 4 to the outer surface of the peripheral wall of the cylinder 2 facing the water jacket 3 surrounding the cylinder 2 in the cylinder block 1, After installing the temperature sensor 5 for measuring the temperature of the peripheral wall of the cylinder 2, the internal combustion engine is operated and the strain amount of the peripheral wall of the cylinder 2 is measured via the strain gauge 4, while the cylinder 2 is connected via the temperature sensor 5. The amount of thermal expansion is obtained by measuring the temperature of the peripheral wall.

  According to this measurement method, it is possible to measure the amount of thermal deformation of the bore inner surface of the cylinder 2 during the operation of the internal combustion engine at high rotation and / or high load, which has been difficult in the past.

  Furthermore, using the measurement result obtained by this measurement method, it becomes easier to achieve both a reduction in mechanical loss and a reduction in the consumption of lubricating oil, which are in a trade-off relationship. If the tension of the piston ring is increased, the consumption of lubricating oil can be suppressed, while the mechanical loss increases. The ability to measure the amount of thermal deformation of the bore inner surface under conditions of various internal combustion engine operating ranges (engine speed and engine load) and various cylinder 2 peripheral wall temperatures (or cooling water temperature) It is possible to quantitatively evaluate the influence of the mechanical loss and the consumption of lubricating oil. And it can greatly contribute to the design of the optimum specifications of the piston ring so that the mechanical loss is not remarkably increased while reducing the consumption amount of the lubricating oil in the operation region of high rotation or high load.

  The present invention is not limited to the embodiment described in detail above. In particular, it is needless to say that the installation location and the number of installations of the strain gauges 4 and 6 and the temperature sensor 5, in other words, the measurement location of the amount of thermal deformation on the peripheral wall of the cylinder 2 are not limited to the illustrated example. The installation location and the number of installations of the strain gauges 4 and 6 and the temperature sensor 5 may be increased, and the thermal deformation of the inner surface of the peripheral wall of the cylinder 2 may be investigated in more detail.

  In addition, the specific configuration of each part can be variously modified without departing from the gist of the present invention.

  The present invention can be used for measuring the amount of thermal deformation of the inner surface of the peripheral wall of a cylinder of an internal combustion engine mounted on a vehicle or the like.

DESCRIPTION OF SYMBOLS 1 ... Cylinder block 2 ... Cylinder 3 ... Water jacket 4 ... Strain gauge 5 ... Temperature sensor (thermocouple)

Claims (1)

In the cylinder block, a strain gauge is attached to the outer surface of the peripheral wall of the cylinder facing the water jacket surrounding the cylinder, and the internal combustion engine is operated after installing a temperature sensor for measuring the temperature of the peripheral wall of the cylinder.
The amount of thermal deformation of the inner surface of the cylinder peripheral wall of the internal combustion engine is obtained by measuring the temperature of the cylinder peripheral wall via a temperature sensor while measuring the amount of strain on the cylinder peripheral wall via a strain gauge. Measuring method.

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