internal combustion engine

Abstract

To provide an auxiliary chamber type internal combustion engine that can appropriately cool an auxiliary chamber.SOLUTION: An internal combustion engine comprises a main combustion chamber 2, and an auxiliary chamber 3 provided in the main combustion chamber 2. The auxiliary chamber 3 comprises an injection hole 12 that is a passage connecting an outer surface facing the main combustion chamber 2 and an inner surface facing the inside of the auxiliary chamber 3, and comprises an extended member 15 forming at least a portion of an inner surface of the injection hole 12, extending from the inner surface, through between the inner and outer surfaces of the auxiliary chamber 3 without being exposed to any of the inner surface and the inside of the main combustion chamber 2, to the outside of the auxiliary chamber 3, and made of a raw material having higher thermal conductivity than that of a raw material constituting the auxiliary chamber 3.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an internal combustion engine. [Background technology]

[0002] In a pre-chamber internal combustion engine, which has a pre-chamber within the main combustion chamber, a mixture of fuel and intake air is supplied to the pre-chamber and ignited in the pre-chamber by a spark plug. When a flame is formed in the pre-chamber, this flame is injected into the main combustion chamber through multiple nozzle holes formed in the pre-chamber. The injected flames then ignite the mixture in the main combustion chamber. This achieves a good combustion state in the main combustion chamber (see, for example, Patent Document 1 below).

[0003] In an internal combustion engine with a pre-chamber, the pre-chamber becomes hot as the air-fuel mixture is burned, which can cause damage to the pre-chamber or cause unburned gas to self-ignite on the pre-chamber wall at a high temperature. Therefore, for example, in Patent Document 2 listed below, a pre-chamber cooling water passage is formed inside the wall of the pre-chamber, and cooling water is passed through the passage to cool the entire pre-chamber. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-84875 [Patent Document 2] Japanese Patent Application Publication No. 2018-168849 Summary of the Invention [Problem to be solved by the invention]

[0005] In an internal combustion engine with a pre-chamber, the area around the injection hole formed in the pre-chamber is heated the most by the flame and therefore needs to be cooled efficiently. However, if the entire pre-chamber is cooled, as in the configuration of Patent Document 2, it may become overcooled, which may cause cooling loss.

[0006] Therefore, an object of the present invention is to appropriately cool the pre-combustion chamber in a pre-combustion chamber type internal combustion engine. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention provides: A main combustion chamber; an auxiliary chamber provided within the main combustion chamber; The auxiliary chamber has an injection hole which is a passage connecting an outer surface facing the main combustion chamber with an inner surface facing the interior of the auxiliary chamber, and the auxiliary chamber has an extension member which forms at least a part of the inner surface of the injection hole and extends from the inner surface to the outside of the auxiliary chamber through between the inner and outer surfaces of the auxiliary chamber without being exposed to either the inner surface or the interior of the main combustion chamber, and which is made of a material with a higher thermal conductivity than the material composing the auxiliary chamber.

[0008] In the above configuration, It is preferable that the extension member is made of a material having a higher electrical conductivity than the material that makes up the sub-chamber, and that a portion of the extension member is earthed.

[0009] In all of the above configurations: It is preferable that the configuration further includes an electrode member that is electrically insulated from the extension member and to which power is supplied, and that forms at least a part of the inner surface of the injection hole, and a measuring unit that measures the current value between the extension member and the electrode member.

[0010] In the configuration including the electrode member, It is preferable that a plurality of the nozzle holes are provided, the extension members are provided independently for each of the plurality of nozzle holes, and the measuring unit is configured to individually measure the current value between the extension members provided for each of the nozzle holes and the electrode members.

[0011] In the configuration including the electrode member, It is preferable that the extension members are arranged at intervals from the inner surface side to the outer surface side within the nozzle hole, and that the measuring unit is configured to individually measure the current value between the electrode member and the extension members arranged in multiple numbers within the nozzle hole. [Effects of the Invention]

[0012] In this invention, in an auxiliary chamber type internal combustion engine, an extension member made of a highly thermally conductive material is provided that runs from the inner surface of the injection hole through between the inner and outer surfaces of the auxiliary chamber to the outside of the auxiliary chamber without being exposed to either the inner surface of the auxiliary chamber or the main combustion chamber.This effectively cools the area around the injection hole in the auxiliary chamber, which tends to become hot, while preventing the entire auxiliary chamber from becoming overcooled. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a cross-sectional view showing a main part of a first embodiment of an internal combustion engine according to the present invention. [Figure 2] FIG. 2 is an exploded cross-sectional view of a main part of the internal combustion engine shown in FIG. [Figure 3] FIG. 2 is a perspective view of an auxiliary chamber used in the internal combustion engine shown in FIG. [Figure 4] FIG. 4 is a perspective view of an extension member used in the auxiliary chamber shown in FIG. 3. [Figure 5] FIG. 10 is a perspective view showing a modified example of the extension member. [Figure 6] FIG. 4 is a cross-sectional view showing a main part of a second embodiment of an internal combustion engine according to the present invention. [Figure 7] FIG. 7 is a perspective view of an auxiliary chamber used in the internal combustion engine shown in FIG. 6. [Figure 8] FIG. 7 is an example of a circuit diagram for measuring jet flame cycle fluctuations used in the internal combustion engine shown in FIG. 6. [Figure 9] FIG. 11 is a perspective view of a main part of an auxiliary combustion chamber used in a third embodiment of an internal combustion engine according to the present invention. [Figure 10] 10 is a graph showing current values ​​measured in the internal combustion engine shown in FIG. 9. [Figure 11] FIG. 10 is a perspective view of a modified example of the main part of the auxiliary chamber shown in FIG. 9. DETAILED DESCRIPTION OF THE INVENTION

[0014] A first embodiment of an internal combustion engine 1 according to the present invention will be described with reference to the drawings. As shown in Fig. 1, this internal combustion engine 1 is an auxiliary combustion chamber type internal combustion engine 1 (gasoline engine) whose main components are a main combustion chamber 2 and an auxiliary combustion chamber 3 provided within the main combustion chamber 2. Note that this drawing shows the main part of one of the multiple cylinders of the internal combustion engine 1.

[0015] The main combustion chamber 2 is formed by a cylinder head 4, a cylinder block 5, and a piston 6 that reciprocates within the cylinder block 5. The cylinder head 4 is provided with an intake passage 7 that sends air into the main combustion chamber 2, an intake valve 8 that opens and closes the intake passage 7, an exhaust passage 9 that exhausts combustion gas from the main combustion chamber 2, and an exhaust valve 10 that opens and closes the exhaust passage 9. The cylinder head 4 also has a cooling water passage 11 through which cooling water flows. In this embodiment, the internal combustion engine 1 has an injection device in the intake passage 7, and mixes intake air and fuel in the intake passage 7 and the main combustion chamber 5, but the invention is not limited to this configuration.

[0016] The auxiliary chamber 3 is provided so as to protrude downward into the main combustion chamber 2. The auxiliary chamber 3 has a plurality of injection holes 12, which are passages connecting the outer surface facing the main combustion chamber 2 with the inner surface facing the auxiliary chamber 3. As shown in FIGS. 2 to 4 , the auxiliary chamber 3 is provided with an extension member 15 having an annular first member 13 that forms at least a part of the inner surface of the injection hole 12 (the surface between the outer end and inner end of the auxiliary chamber 3). The extension member 15 is connected to the first member 13 and extends from the inner surface of the auxiliary chamber 3 between the inner and outer surfaces of the auxiliary chamber 3 to the outside of the auxiliary chamber 3 (in this embodiment, above the upper end surface of the auxiliary chamber 3) without being exposed to either the inner surface of the auxiliary chamber 3 or the main combustion chamber 2. The auxiliary chamber 3 is made of an aluminum alloy, while the extension member 15 is made of copper, which has higher thermal and electrical conductivity than aluminum alloy. The second member 14 may be exposed to the outside of the auxiliary chamber 3 at a portion of the outer surface of the auxiliary chamber 3 that does not face the main combustion chamber 2 (for example, the upper end of the outer surface of the auxiliary chamber 3, i.e., the radially outer surface of the flange portion extending radially outward from the upper end of the auxiliary chamber 3).

[0017] The sub-chamber 3 is provided so as to be connectable to the underside of a plug holder 17 that holds a spark plug 16. The tip of the spark plug 16 is positioned so as to face into the sub-chamber 3. A copper wire 18 is embedded in the plug holder 17, and the extension member 15 is grounded to the vehicle frame (not shown) via the wire 18. With the sub-chamber 3 connected to the plug holder 17, the second member 14 of the extension member 15 is connected to the wire 18. The plug holder 17 is fixed to the cylinder head 4. In this embodiment, the sub-chamber 3 and the spark plug 16 are separate members, but it is also possible to use a spark plug 16 that is integrated with the sub-chamber 3.

[0018] In the internal combustion engine 1 according to the first embodiment, the first member 13 of the extension member 15 forms at least a part of the inner surface of the injection hole 12, and the extension member 15 is made of copper, which has a higher thermal conductivity than the material of the auxiliary combustion chamber 3. This allows the heat of the injection hole 12, which is likely to become hot due to the injection of flame, to escape to the outside of the auxiliary combustion chamber 3 via the extension member 15, thereby quickly cooling the auxiliary combustion chamber 3 and preventing the entire auxiliary combustion chamber 3 from becoming overcooled and causing cooling loss. Furthermore, the second member 14 of the extension member 15 extends to the outside of the auxiliary combustion chamber 3 without being exposed to either the inner surface of the auxiliary combustion chamber 3 or the main combustion chamber 2, so the second member 14 is less likely to be heated by the heat of combustion in the main combustion chamber 2 and the auxiliary combustion chamber 3. This allows the heat around the injection hole 12 to escape smoothly to the outside of the auxiliary combustion chamber 3.

[0019] In the internal combustion engine 1 according to the first embodiment, the extension member 15 is grounded to the frame of the vehicle body, so heat from the injection hole 12 can be released to the outside of the internal combustion engine 1. In addition, static electricity buildup in the auxiliary combustion chamber 3 can be suppressed, preventing fuel from adhering to the auxiliary combustion chamber 3 due to static electricity. The position of the ground is not limited to the frame of the vehicle body and can be changed as appropriate.

[0020] As a modification of the extension member 15, as shown in Fig. 5, the copper second member 14 may be formed in a jacket shape to surround the spark plug 16. This effectively cools the area around the injection hole 12 as well as the area around the spark plug 16, which tends to trap heat, and thus prevents the spark plug 16 from melting.

[0021] A second embodiment of an internal combustion engine 1 according to the present invention is shown in Fig. 6. The internal combustion engine 1 according to the second embodiment includes, in addition to the extension member 15, an electrode member 19 that forms at least a part of the inner surface of the injection hole 12 and is electrically insulated from the extension member 15 and is supplied with power. A measurement unit 20 (ammeter) that measures the current value between the extension member 15 and the electrode member 19 is provided outside the internal combustion engine 1 between the extension member 15 and the electrode member 19. The extension member 15 is connected to the negative electrode of the measurement unit 20, and the electrode member 19 is connected to the positive electrode of the measurement unit 20. The extension member 15 is grounded via the negative electrode of the measurement unit 20.

[0022] As shown in FIG. 7 , the auxiliary chamber 3 according to the second embodiment has a plurality of injection holes 12 (four in this embodiment), and an extension member 15 (negative electrode) is provided for each of the injection holes 12. Specifically, each injection hole 12 is provided with a first member 13 shaped to fit the inner surface of the injection hole 12 and a second member 14 extending from the upper end of the first member 13 to the upper surface of the auxiliary chamber 3. An electrode member 19 is provided between the inner and outer surfaces of the auxiliary chamber 3 and has an insertion hole through which the extension member 15 is inserted. An insulating layer 21 insulates the extension member 15 from the electrode member 19, and the electrode member 19 functions as a common positive electrode for all of the extension members 15. The inner and outer surfaces of the electrode member 19 are covered with, for example, an insulating material. A measuring unit 20 is configured to individually measure the current value between the electrode member 19 and the extension member 15 provided for each injection hole 12.

[0023] The extension member 15, electrode member 19, and insulating layer 21 are exposed on the inner surface of the nozzle hole 12. Specifically, the extension member 15 is located on one side of the nozzle hole 12 (one radial side of the auxiliary chamber 3), the electrode member 19 is located on the other side of the nozzle hole 12, and the insulating layer 21 is located between them. Because the extension member 15 and the electrode member 19 are electrically insulated by the insulating layer 21, no current flows even when a voltage is applied between the two members 15 and 19. However, when a flame passes through the nozzle hole 12 as a result of combustion in the auxiliary chamber 3, electrons and positive ions are generated by the oxidation reaction (chemical ionization of fuel molecules) during this combustion, and the conductivity of these electrons and positive ions generates a current between the extension member 15 and the electrode member 19, a flame conduction phenomenon.

[0024] The magnitude of the current value associated with the flame conduction phenomenon increases as the intensity (jet intensity) of the flame injected from the nozzle hole 12 increases. It can be determined that the greater the jet intensity, the higher the temperature of the injected flame.

[0025] The internal combustion engine 1 according to the second embodiment is capable of quantitatively evaluating jet strength based on the flame conduction phenomenon. For example, thresholds (lower and upper limits) can be set in advance for the current value, and it can be determined that a flame misfire has occurred when the current value is equal to or less than the lower limit. Furthermore, when vibration is detected by a knock sensor (not shown) and the current value is equal to or greater than the upper limit, it can be determined that combustion accompanied by a shock caused by the propagation and collision of strong flames (jet shock) has occurred. When vibration is detected by the knock sensor and the current value is smaller than the upper limit, it can be determined that knocking has occurred. In this way, by combining the current measurement results by the measurement unit 20 and the vibration detection results by the knock sensor, it is possible to appropriately determine the state of the flame (particularly, to distinguish between jet shock and knocking, which have similar frequency characteristics detected by the knock sensor).

[0026] In this way, by being able to determine the state of the flame, appropriate control can be performed according to the situation, for example, when jet shock is occurring, the fuel injection timing can be delayed to reduce the amount of fuel supplied to the pre-chamber, thereby weakening the jet strength and eliminating the jet shock, while when knocking is occurring, the ignition timing can be retarded to eliminate the knocking.

[0027] In this embodiment, the measuring unit 20 is configured to measure the current value between the extension members 15 and the electrode members 19 provided in the respective nozzle holes 12 individually.

[0028] The wires extending from the four extension members 15 and the electrode member 19 are drawn out of the engine through the spark plug insertion port and connected to a jet flame cycle variation measurement circuit provided in the engine control device. An example of this circuit is shown in Figure 8. Sensor values ​​from a knock sensor and a crank angle sensor (neither of which are shown) are also input to this circuit.

[0029] If the nozzle hole 12 becomes clogged, cyclic fluctuations in flame injection (flame variations in each nozzle hole within the same cycle) occur, which can lead to uneven combustion in the main combustion chamber 2. However, because the jet strength of each nozzle hole 12 can be measured individually, it is possible to easily identify the nozzle hole 12 that has become clogged. When a clogged nozzle hole 12 is identified, a message urging maintenance may be displayed on the vehicle monitor or the like.

[0030] Furthermore, by measuring the duration of the high jet intensity state at each injection hole 12, it is possible to predict the high temperature state of the wall surface of the pre-chamber 3, and from this prediction, it is possible to predict the occurrence of self-ignition (knocking) of unburned gas caused by contact with the heated wall surface of the pre-chamber 3. If the occurrence of knocking is predicted, a correction can be made to retard the ignition timing. In this embodiment, too, since the extension member 15 extends outside the pre-chamber 3, a cooling effect of the injection hole 12 can be expected.

[0031] FIG. 9 shows an injection hole 12 of the auxiliary chamber 3 according to a third embodiment of the internal combustion engine 1 according to the present invention. In the internal combustion engine 1 according to the third embodiment, a plurality of extension members 15 (negative electrodes) (two in this embodiment) are arranged at intervals within the injection hole 12 from the inner surface side of the auxiliary chamber 3 toward the outer surface side (see the arrows in FIG. 9 ), and a cylindrical electrode member 19 (positive electrode) is provided along the inner surface of the injection hole 12. An insulating layer 21 is provided between each extension member 15 and the electrode member 19. The electrode member 19 functions as a common positive electrode for the two extension members 15. A measuring unit 20 is configured to measure the current values ​​between the two extension members 15 and the electrode member 19 individually.

[0032] The flame injected from the nozzle hole 12 first reaches the extension member 15 located at the back side of the nozzle hole 12, and then, with a slight time lag, reaches the extension member 15 located at the tip side. For this reason, as shown in Figure 10, the current value between the extension member 15 at the back side and the electrode member 19 rises first, and then the current value between the extension member 15 at the tip side and the electrode member 19 rises after that.

[0033] By arranging the extension members 15 in this manner, the speed of the flame injected from the nozzle hole 12 can be measured from the time difference between the rise times of the current value of each extension member 15. Since the flame speed increases as the jet strength increases, the jet strength can be determined more accurately by evaluating the magnitude of the current value between the extension members 15 and the electrode member 19 together with the flame speed.

[0034] Although Figure 9 shows a configuration in which only the extension members 15 are arranged side by side along the flame injection direction, as shown in Figure 11, the same effect can be achieved by pairing the extension members 15 and electrode members 19 and arranging them side by side along the flame injection direction (see the arrow in Figure 11).

[0035] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. Therefore, the scope of the present invention is defined by the claims rather than the above description, and it is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0036] 1. Internal combustion engine 2 Main combustion chamber 3 Antechamber 4 Cylinder head 5 Cylinder block 6 pistons 7 Intake passage 8 intake valve 9 Exhaust passage 10 Exhaust valve 11 Cooling Channel 12 nozzle holes 13 First member 14 Second member 15 Extension member 16 Spark plug 17 Plug holder 18 Wiring 19 Electrode material 20 Measurement section 21 Insulating layer

Claims

1. A main combustion chamber; an auxiliary chamber provided within the main combustion chamber; the auxiliary chamber has an injection hole which is a passage connecting an outer surface facing the main combustion chamber with an inner surface facing the interior of the auxiliary chamber, and an extension member which forms at least a part of the inner surface of the injection hole and extends from the inner surface of the injection hole to the outside of the auxiliary chamber, passing between the inner and outer surfaces of the auxiliary chamber without being exposed to either the inner surface facing the interior of the auxiliary chamber or the inside of the main combustion chamber, and which is made of a material having a higher thermal conductivity than a material constituting the auxiliary chamber; an electrode member that is electrically insulated from the extension member and forms at least a part of the inner surface of the injection hole; and a measurement unit that measures a current value between the extension member and the electrode member; An internal combustion engine equipped with

2. 2. The internal combustion engine according to claim 1, wherein the extension member is made of a material having a higher electrical conductivity than a material constituting the auxiliary chamber, and a portion of the extension member is earthed.

3. 2. The internal combustion engine according to claim 1, wherein a plurality of the nozzle holes are provided, the extension members are independently provided for the plurality of nozzle holes, and the measuring unit is configured to individually measure a current value between the extension members and the electrode members provided for the respective nozzle holes.

4. 2. The internal combustion engine according to claim 1, wherein a plurality of the extension members are arranged at intervals from the inner surface side toward the outer surface side within the injection hole, and the measurement unit is configured to individually measure current values ​​between the plurality of extension members arranged within the injection hole and the electrode member.

Images