JPH0222325B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for detecting knocking in a water-cooled internal combustion engine.

In order to improve the accuracy of knocking detection in internal combustion engines, the present inventor previously researched vibrations in the engine block of a water-cooled internal combustion engine, and found that when knocking occurs in the combustion chamber, the cylinder between the combustion chamber and the water chamber It vibrates at a frequency corresponding to the pressure vibration caused by knocking in the combustion chamber, and the volume of the water chamber increases or decreases due to the vibration, causing a pressure change in the cooling water in the water chamber.On the other hand, vibrations other than knocking cause We learned that pressure changes including vibration frequency components due to knocking hardly occur in the cooling water in the water chamber. Based on the results of this research,
He invented a knocking detection device characterized in that a pressure gauge for detecting pressure changes is connected to a water chamber in which pressure changes in cooling water occur via a cylinder due to knocking in the combustion chamber. However,
Although this knocking detection device has higher accuracy in detecting knocking than previous devices, it is still not sufficient.

An object of the present invention is to provide a knocking detection device that can detect knocking in a water-cooled internal combustion engine with higher accuracy.

In order to achieve the above object, the present inventor conducted a detailed study on how pressure changes occur in the cooling water in the water chamber due to knocking in the combustion chamber in a water-cooled internal combustion engine, and found the following. learned.

(1) When knocking occurs in the combustion chamber, the top surface of the piston sliding inside the combustion chamber vibrates, and the piston is struck and pressed against one side of the cylinder by slap during the expansion stroke after passing through top dead center. Then, the vibration of the top surface of the piston is transmitted to the thrust side of the cylinder against which the piston is pressed, and the thrust side of the cylinder vibrates greatly at a frequency corresponding to the pressure vibration caused by knotting in the combustion chamber, causing distortion. A large pressure change occurs in the cooling water in the water chamber adjacent to the side.

Note that if the knocking is large and the vibration of the top surface of the piston is large, the cylinder will vibrate not only on the thrust side but also on the entire circumference including the anti-thrust side.

(2) On the other hand, the vibration of the piston top surface caused by notching is not directly transmitted to the anti-thrust side of the cylinder, where the piston does not strike during the expansion stroke where knocking occurs, and the anti-thrust side of the cylinder Therefore, the cooling water in the water chamber in contact with the anti-thrust side of the cylinder does not vibrate as much as the cooling water in the water chamber in contact with the thrust side.

(3) In addition, the pressure vibration waves of the cooling water in the water chamber generated by the strain vibration of the cylinder due to knocking have a high frequency of approximately 6 to 10 KHz, and are more linear than pressure vibration waves with lower frequencies. is high.

The present invention has been completed based on the research results in the above-mentioned sections 1 and 2.

That is, a combustion chamber in which a piston slides is formed within the cylinder, and the piston is struck and pressed against one side of the cylinder by a slap during the expansion stroke after passing through top dead center, and the piston is pressed against one side of the cylinder by a slap.
In a water-cooled internal combustion engine that has a water chamber through which cooling water flows, a pressure gauge that detects changes in the pressure of the cooling water that occur in the water chamber through the cylinder due to knocking in the combustion chamber is installed after the piston passes through top dead center. This knocking detection device is characterized in that it is connected to a water chamber on the thrust side of the cylinder that is struck and pressed by a slap during the expansion stroke.

This knocking detection device uses a pressure gauge that detects changes in cooling water pressure due to knocking to detect pressure changes on the side where the pressure change in cooling water due to knocking increases, as is clear from the research results in Sections 1 and 2 above. Since it is connected to the water chamber, knocking detection accuracy is higher than when connected to the water chamber on the opposite side.

The embodiments of the present invention have been completed based on the research results in Section 3 above.

That is, in the knocking detection device for an internal combustion engine according to the present invention, the pressure receiving part of the pressure gauge is protruded from the wall surface of the water chamber on the thrust side of the cylinder into the cooling water in the water chamber. It is.

In this knocking detection device, the pressure receiving part of the pressure gauge that detects the pressure change of the cooling water due to knocking protrudes from the water chamber wall surface into the cooling water in the water chamber. The pressure oscillation waves of the cooling water caused by knocking, which travels in a straight line, can be detected with high sensitivity at the pressure receiving part of the pressure gauge, compared to when the pressure receiving part of the pressure gauge does not protrude from the water chamber wall surface into the cooling water in the water chamber. Therefore, the detection accuracy of knocking is high. In addition, since the pressure receiving part of the pressure gauge is cooled by the cooling water in the water chamber, even if the temperature around the internal combustion engine becomes high, the pressure receiving part of the pressure gauge will not be heated to a higher temperature than the temperature of the cooling water. do not have.

Another embodiment of the present invention is the knocking detection device for an internal combustion engine according to the present invention, in which the pressure receiving part of the pressure gauge is formed on the wall surface of the water chamber on the thrust side of the cylinder, and the diameter of the opening is greater than or equal to the depth. This is a knocking detection device characterized in that it is mounted in a mounting recess of the same size.

In this knocking detection device, the pressure receiving part of the pressure gauge is installed in the mounting recess formed in the wall of the water chamber, so the water chamber between the cylinder and the wall of the water chamber is narrow, and the pressure receiving part of the pressure gauge is placed in the cooling water in the water chamber. Even if it is not possible to protrude the pressure gauge, the pressure receiving part of the pressure gauge can be installed so as to protrude into the cooling water in the water chamber. In addition, since the opening diameter of the mounting recess where the pressure receiving part of the pressure gauge is mounted is larger than the depth, pressure vibration waves of the cooling water that travel in a straight line due to knotting can easily enter the mounting recess, and the pressure of the cooling water due to knotting can easily enter the mounting recess. Vibration waves can be detected with high sensitivity by the pressure receiving part of the pressure gauge. After all, even if the water chamber between the cylinder and the water chamber wall is too narrow for the pressure receiving part of the pressure gauge to protrude, the pressure receiving part of the pressure gauge can be protruded into the cooling water in the water chamber to improve the accuracy of knocking detection. Along with being able to
The pressure receiving part of the pressure gauge can be cooled by cooling water in the water chamber.

Next, examples of the present invention will be described.

First Embodiment (See Figures 1 to 4) A water-cooled internal combustion engine to which the knocking detection device of this example is installed has four cylinders 2 arranged in series, as shown in Figures 1 and 2. This is a gasoline engine for automobiles arranged on a cylinder block in which a combustion chamber 1 with a piston 5 slidably fitted into each cylinder 2 is formed, and a water chamber 3 through which cooling water flows around the outside of each cylinder 2 is formed. A cylinder head 8 equipped with an intake valve, an exhaust valve, and a water chamber (not shown) is combined to form a crank chamber in which the crankshaft 7 is pivotally supported on the lower side of the cylinder block, and each crank pin of the crankshaft 7 and each piston are connected to each other. 5 piston pins are connected by connecting rods 6, respectively.

The knocking detection device of this embodiment is designed to connect the outer circumferential wall to the wall of the water chamber 3 on the thrust side of the cylinder 2, that is, the central part of the outer circumferential wall 4 of the cylinder block, against which the piston 5 is struck and pressed by the slap during the expansion stroke of the engine. A screw detection hole 9 communicating with the water chamber 3 between the cylinders 2 is provided through the cylinder 2, and a bolt-shaped mounting portion 11 of a pressure gauge 10 is screwed into the detection hole 9 and tightened. On the other hand, the bolt-shaped mounting part 11 of the pressure gauge is mounted on the outer peripheral wall 4 of the cylinder block, and the pressure receiving part 13 protruding from the tip of the bolt-shaped mounting part 11 is inserted into the water chamber from the wall surface of the water chamber 3, that is, the outer peripheral wall 4 surface of the cylinder block. 3 and protrudes into the cooling water in the water chamber.

As shown in FIGS. 3 and 4, the pressure gauge 10 described above is constructed by fitting the tip of a handle 14 protruding from the tip of a bolt-like mounting portion 11 into a connecting hole penetrating the peripheral wall of a frame tube 15. Then, a short cylindrical frame 15 was provided protrudingly at the tip of the bolt-shaped mounting part 11, and both open ends of the frame 15 were coated with pressure receiving membranes 16, which were arranged coaxially within the frame 15. The pressure receiving section 13 is constructed by sandwiching the strain tube 17 between both pressure receiving membranes 16, 16, and pasting a strain game 18 on the outer circumferential surface of the strain tube 17, where distortion occurs due to the pressure applied to both the pressure receiving membranes 16, 16. A lead wire 19 of the strain gauge 18 is guided to the outside through a central hole 12 extending through the mounting portion 11.

In the knocking detection device of this example installed in a water-cooled four-cylinder gasoline engine, when knocking occurs in the combustion chamber 1, the knocking causes the top surface of the piston 5 sliding in the combustion chamber 1 to vibrate, causing the piston to vibrate. 5 is struck against the cylinder 2 by a slap during the expansion stroke after passing the top dead center,
The thrust side of the cylinder 2 against which the piston 5 is pressed vibrates greatly, causing a large pressure change in the cooling water in the water chamber 3 that is in contact with the thrust side, and this large pressure change is added to the pressure receiving membranes 16, 16 of the pressure gauge. , strain occurs in the strain tube 17, and the strain is transmitted to the strain gauge 18.
As a result, the occurrence of knocking is detected.

The knocking detection device of this example connects the pressure gauge 10 to the water chamber 3 on the side where the pressure change of the cooling water due to knocking increases, and also connects the pressure receiving part 13 of the pressure gauge to the cooling water chamber 3 from the wall surface of the water chamber. Since it protrudes into the water, the detection accuracy of knotting is high. For example, not only the knocking that occurs in both combustion chambers 1, 1 in the center near the pressure gauge 10, but also the knocking that occurs in the combustion chambers 1, 1 at the ends farthest from the pressure gauge 10 can be accurately detected. .

Furthermore, in the knocking detection device of this example, since the pressure receiving part 13 of the pressure gauge protrudes into the cooling water in the water chamber 3, the pressure receiving part 13 of the pressure gauge is cooled by the cooling water in the water chamber 3. Even if the temperature around the engine increases, the pressure receiving part 13 will not be heated to a higher temperature than the cooling water temperature.

Second Embodiment (See Figure 5) Compared to the previous example, the knocking detection device of this example uses a water-cooled two-cylinder or three-cylinder gasoline engine that is equipped with a pressure gauge, and a piezoelectric element is installed in the pressure gauge. The only difference is that the pressure gauge 22 used is used, and the pressure receiving plate 25 of the pressure gauge is placed on the same plane as the water chamber wall surface and does not protrude into the cooling water in the water chamber 3.Other points are the same as in the first embodiment. It is the same as the example. That is, the knocking detection device of this embodiment detects water between the outer circumferential wall and the cylinder at the center of the wall of the water chamber 3 on the thrust side of the cylinder, that is, the outer circumferential wall 4 of the cylinder block, where the piston is struck by the slap during the expansion stroke of the engine. A screw detection hole 9 that communicates with the chamber 3 is provided through the detection hole 9, and the tip attachment threaded portion 24 of the housing 23 of the pressure gauge 22 is screwed into the detection hole 9 via a washer 21 to tighten the detection hole 9. While the pressure gauge 22 is closed, the pressure gauge 22 is connected to the outer circumferential wall 4 of the cylinder block.
The surface of the pressure receiving plate 25 at the tip of the pressure gauge 22 is aligned with the inner surface of the outer peripheral wall 4 and brought into contact with the cooling water in the water chamber 3. Above pressure gauge 2 connected to water chamber 3
2, two piezoelectric elements 28, 28 with an electrode 29 sandwiched between a pressure transmitting member 26 in contact with the back surface of the pressure receiving plate 25 at the tip of the housing and a substrate 27 supported in the housing are connected to the electrode 29. The terminal 30 protrudes into a connector 31 screwed into the rear end opening of the housing 23.

In the knocking detection device of this example, when knocking occurs in the combustion chamber, the knocking causes a large pressure change in the cooling water in the water chamber 3 through the cylinder, and this pressure change is transmitted to the pressure receiving plate 2 of the pressure gauge.
5, the piezoelectric elements 28, 28 are pressed through the pressure transmission member 26, and the output voltage of the piezoelectric elements 28, 28 is output from the electrode 29 to the terminal 30.

The knocking detection device of this embodiment has high knocking detection accuracy because the pressure gauge 22 is connected to the water chamber 3 on the side where the pressure change of the cooling water due to knocking is large. In addition, the pressure receiving plate 25 of the pressure gauge is connected to the water chamber 3.
Although the engine does not protrude into the cooling water inside the
An engine with a small number of cylinders or three cylinders,
Since the distance from the pressure receiving plate 25 of the pressure gauge to each combustion chamber is short, knocking occurring in each combustion chamber cannot be sufficiently detected by the pressure gauge 22 in which the pressure receiving plate 25 does not protrude into the cooling water in the water chamber 3. can.

Third Embodiment (Refer to Fig. 6) The knocking detection device of this embodiment is applied to a cylinder 2 against which a piston 5 is struck by a slap during the expansion stroke of a water-cooled in-line four-cylinder gasoline engine.
A truncated conical mounting recess 41 with an opening diameter D larger than the depth L is formed in the center of the wall surface of the water chamber 3 on the thrust side, that is, the inner surface of the outer circumferential wall 4 of the cylinder block. A pressure gauge 10 similar to that in the embodiment is attached in the same manner as in the first embodiment. Components similar to those in the first embodiment are designated by the same reference numerals in FIG. 6, and their explanation will be omitted.

In the knocking detection device of this example, the pressure receiving part 13 of the pressure gauge is attached to the mounting recess 41 formed on the wall surface of the water chamber 3, so if the water chamber 3 is too narrow for the pressure receiving part 13 of the pressure gauge to protrude, Also, the pressure receiving part 13 of the pressure gauge can be installed so as to protrude into the cooling water in the water chamber 3. In addition, since the opening diameter D of the mounting recess 41 is larger than the depth L, the pressure vibration waves of the cooling water that travels in a straight line due to knotting are likely to enter into the mounting recess 41, and the pressure vibration waves of the cooling water due to knotting are easily penetrated into the mounting recess 41. The pressure receiving part 13 of the pressure gauge in the recess 41 can detect the pressure with high sensitivity. In addition, the bottom plate 42 of the mounting recess to which the pressure gauge 10 is mounted is narrower than the water chamber 3 wall, that is, the outer peripheral wall 4 of the cylinder block, and has a higher natural frequency. The first noise is the noise detected by the pressure gauge 10 attached to the bottom plate 42 of the recess.
This is less noise than that detected by the pressure gauge attached to the outer circumferential wall 4 of the cylinder block as in the second embodiment.

In addition, when the shape of the opening of the attachment recess 41 is not circular, the diameter of a circular opening having the same area as the non-circular opening is defined as the opening diameter D.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a knocking detection device according to a first embodiment of the present invention, FIG. 2 is a cross-sectional view taken along line A-A in FIG. 1, and FIG. 3 is a pressure gauge mounting part of a knocking detection device of the same example. 4 is a partially broken enlarged plan view of FIG. 3, and FIG. 5 is a partially broken plan view of the pressure gauge mounting part of the knocking detection device according to the second embodiment of the present invention. FIG. 6 is a cross-sectional view of a pressure gauge mounting portion of a knocking detection device according to a third embodiment of the present invention. 1: Combustion chamber, 2: Cylinder, 3: Water chamber, 4: Water chamber 3 wall, cylinder block outer peripheral wall, 5: Piston, 10: Pressure gauge, 13: Pressure receiver, 22: Pressure gauge, 41: Mounting recess, D: opening diameter, L: depth.

Claims (1)

[Claims] 1. A combustion chamber in which a piston slides is formed in the cylinder, and the piston is struck and pressed against one side of the cylinder by a slap during the expansion stroke after passing the top dead center, In a water-cooled internal combustion engine that has a water chamber outside the cylinder through which cooling water flows, a pressure gauge that detects changes in the pressure of the cooling water that occur in the water chamber through the cylinder due to knocking in the combustion chamber is connected to the piston. 1. A knocking detection device, characterized in that the knocking detection device is connected to a water chamber on the thrust side of a cylinder that is struck and pressed by a slap during an expansion stroke after passing through a point. 2. The knocking detection device according to claim 1, wherein the pressure receiving part of the pressure gauge protrudes from the wall surface of the water chamber on the thrust side of the cylinder into the cooling water in the water chamber. 3. Claim 1, characterized in that the pressure receiving part of the pressure gauge is mounted in a mounting recess formed in the wall surface of the water chamber on the thrust side of the cylinder, the opening diameter of which is larger than the depth. The knocking detection device according to item 1 or 2.