JP2010106846A - Multicylinder premix compression self-ignition engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve cycle efficiency, in an engine including a plurality of cylinders and configured to supply air-fuel mixture obtained by premixing fuel with air to each combustion chamber of the plurality of cylinders and to burn the air-fuel mixture by compression self-ignition in each combustion chamber, by reducing dispersion of self-ignition timing in each combustion chamber. <P>SOLUTION: Of cylinders 2a-2d, at least the top part of cylinders 2b and 2c which are relatively difficult to radiate is formed of a material having high heat conductivity, or at least the top part of cylinders 2a and 2d which are relatively easy to radiate is formed of a material having low heat conductivity, whereby the compression end temperature of each combustion chamber in each cylinder is matched to each other. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a multi-cylinder type premixed compression auto-ignition (HCCI) engine.

  A premixed compression self-ignition engine is one that self-ignites by compressing an air-fuel mixture premixed in a combustion chamber. Conventionally, a single-cylinder type having one cylinder, and a plurality of There are multi-cylinder types having cylinders. As an example of the multi-cylinder type, there is an in-line multi-cylinder type in which a plurality of cylinders are arranged in a line.

  In this in-line multi-cylinder type premixed compression self-ignition engine, air and fuel are mixed, then the mixture is distributed according to the number of cylinders and individually supplied to each combustion chamber for combustion. Some employ a so-called simultaneous injection system (see Patent Document 1).

JP 2000-240513 A

  In the in-line multi-cylinder type premixed compression self-ignition engine, a difference occurs in the compression end temperature for each combustion chamber due to the difference in the heat radiation characteristics of each cylinder due to the arrangement of each cylinder in the cylinder block. As a result, the time when the air-fuel mixture self-ignites in each combustion chamber tends to vary.

  Incidentally, in the case of the in-line multi-cylinder type, for example, the cylinders arranged at both ends in the longitudinal direction of the cylinder block radiate heat more easily than the cylinders arranged at the middle in the longitudinal direction. It tends to be lower than the temperature in the combustion chamber in the intermediate cylinder. Therefore, the compression end temperature in the combustion chambers at both ends is lower than the compression end temperature in the intermediate combustion chamber, so that the self-ignition timing in the combustion chambers at both ends is the self-ignition timing in the intermediate combustion chamber. In comparison, the cycle efficiency and the thermal efficiency are lowered.

  An object of the present invention is to reduce variation in self-ignition timing for each combustion chamber in a multi-cylinder type premixed compression self-ignition engine, and to improve cycle efficiency and thermal efficiency.

  The present invention has a plurality of cylinders, and supplies an air-fuel mixture in which fuel and air are mixed in advance to the respective combustion chambers of the plurality of cylinders, and combusts the air-fuel mixture by compression auto-ignition in the respective combustion chambers. It is assumed that the engine will be used.

  The engine includes, for example, a cylinder block having four cylinders arranged in series, a cylinder head mounted on the upper portion of the cylinder block, four pistons inserted into the four cylinders of the cylinder block, and four pistons, respectively. Four independent combustion chambers formed by a connecting rod that supports the cylinder, a crankshaft that moves the connecting rod up and down, an intake surge tank that is attached to the intake port of the cylinder head, four cylinders, four pistons, and a cylinder head And at least an intake system that supplies a mixture of fuel and air.

  According to a first aspect of the present invention, in the engine, at least a top portion of a piston of a cylinder that is relatively difficult to dissipate among the cylinders is formed of a material having a high thermal conductivity so that the compression end temperatures of the combustion chambers of the cylinders are made uniform. As a result, the amount of heat released from the piston of the cylinder, which is relatively difficult to dissipate heat, increases, so that the temperature of each cylinder can be made uniform, and the compression end temperature can be made uniform for each combustion chamber. .

  According to a second aspect of the present invention, in the engine, at least a top part of a piston of each cylinder that is relatively easy to dissipate heat is formed of a material having low thermal conductivity so that the compression end temperatures of the combustion chambers of the cylinders are made uniform. As a result, the amount of heat released from the piston of the cylinder, which is relatively easy to dissipate heat, is reduced, so that the temperature of each cylinder can be made uniform as described above.

  According to a third aspect of the present invention, in the engine, at least the tops of the pistons of all the cylinders are formed of materials having relatively different thermal conductivities according to the heat radiation characteristics of the respective cylinders, and The compression end temperatures are made uniform, and in this case as well, the temperatures of the cylinders can be made uniform as described above.

  According to a fourth aspect of the present invention, in the engine, a piston of a cylinder that is relatively easy to dissipate heat among each cylinder is provided with a heat insulating portion that reduces or blocks heat conduction from the piston to the cylinder. Since the compression end temperature is made uniform, the amount of heat released from the piston of the cylinder that is relatively easy to radiate heat is reduced, so that the temperature for each cylinder can be made uniform as described above.

  In the fourth aspect, as described in the fifth aspect, the heat insulating portion can be a cavity provided in a thick portion of the piston.

  According to a sixth aspect of the present invention, in the engine, oil jet means for injecting oil to a piston of a cylinder that is relatively difficult to dissipate among the cylinders is provided so that the compression end temperatures of the combustion chambers of the cylinders are made uniform. As a result, the pistons of the cylinders that are relatively difficult to dissipate heat are cooled, so that the temperature of each cylinder can be made uniform.

  According to a seventh aspect of the present invention, in the engine, each of the pistons of all the cylinders has an oil jet means for injecting oil, and each of the oil jet means has an oil injection amount for each piston according to a heat radiation characteristic for each cylinder. The compression end temperatures of the combustion chambers of the cylinders are controlled to be uniform, and the cooling capacity of the pistons can be differentiated. Therefore, the temperatures of the cylinders are aligned. It becomes possible.

  According to the present invention, since the compression end temperatures of the respective combustion chambers during the premixed compression self-ignition operation can be made uniform, variations in the self-ignition timing of the respective combustion chambers can be reduced, and the cycle efficiency can be improved.

It is a schematic block diagram which shows Embodiment 1 which concerns on this invention. It is a top view which shows the engine of FIG. 1 typically. FIG. 3 is a cross-sectional view taken along line (3)-(3) in FIG. 2. FIG. 3 is a diagram corresponding to FIG. 2 in an application example 1 of the first embodiment. FIG. 5 is a cross-sectional view taken along line (5)-(5) in FIG. 4. FIG. 6 is a diagram corresponding to FIG. 2 in an application example 2 of the first embodiment. It is an arrow view of the (7)-(7) line cross section of FIG. FIG. 3 is a diagram corresponding to FIG. 2 in Embodiment 2 according to the present invention. FIG. 6 is a diagram corresponding to FIG. 2 in Application Example 1 of Embodiment 2. FIG. 6 is a diagram corresponding to FIG. 2 in an application example 2 of the second embodiment. FIG. 9 is a diagram corresponding to FIG. 2 in Embodiment 3 according to the present invention. FIG. 6 is a diagram corresponding to FIG. 2 in Embodiment 4 according to the present invention. It is an arrow view of the (13)-(13) line cross section of FIG. It is an example of application of Embodiment 4, and is a figure corresponding to FIG. It is an arrow view of the (15)-(15) line cross section of FIG. FIG. 9 is a diagram corresponding to FIG. 2 in Embodiment 5 according to the present invention. FIG. 17 is a cross sectional view taken along line (17)-(17) in FIG. 16. FIG. 9 is an application example of Embodiment 5 and corresponds to FIG. FIG. 19 is a cross-sectional view taken along line (19)-(19) in FIG. 18. FIG. 9 is a diagram corresponding to FIG. 2 in Embodiment 6 according to the present invention. In Embodiment 7 which concerns on this invention, it is a side view which shows a piston. In Embodiment 8 which concerns on this invention, it is a side view which shows a piston. It is a perspective view which shows the piston of Embodiment 8 typically. FIG. 10 is a diagram corresponding to FIG. 2 in Embodiment 9 according to the present invention. It is an example of application of Embodiment 9, and is a figure corresponding to FIG. In Embodiment 10 which concerns on this invention, it is a side view which shows an engine typically. In Embodiment 11 which concerns on this invention, it is a perspective view which shows an engine typically. It is a disassembled perspective view which shows a cylinder block and a head gasket by the structure relevant to Embodiment 11. FIG. FIG. 12 is a diagram corresponding to FIG. 2 in Embodiment 12 according to the present invention. In Embodiment 13 which concerns on this invention, it is a side view which shows an engine typically. It is Embodiment 14 which concerns on this invention, and is a figure corresponding to FIG. FIG. 16 is a diagram corresponding to FIG. 1 in Embodiment 15 according to the present invention. In Embodiment 16 which concerns on this invention, it is a side view which shows an engine typically. In Embodiment 17 which concerns on this invention, it is a side view which shows an engine typically. In Embodiment 18 which concerns on this invention, it is a side view which shows an engine typically. In Embodiment 19 which concerns on this invention, it is a graph which shows the relationship between the closing timing of an intake valve, and an effective compression ratio. In the application example of Embodiment 19, it is a graph which shows the relationship between the closing timing of an intake valve, and an effective compression ratio. In Embodiment 20 which concerns on this invention, it is a graph which shows the relationship between the closing timing of an intake valve, and an effective compression ratio. In the application example of Embodiment 20, it is a graph which shows the relationship between the closing timing of an intake valve, and an effective compression ratio.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<Embodiment 1>
A first embodiment of a multi-cylinder premixed compression self-ignition engine 1 according to the present invention will be described with reference to FIGS. 1 to 3. Here, an in-line four-cylinder premixed compression self-ignition engine is taken as an example. However, the number of cylinders is not particularly limited as long as it is two or more.

  Prior to the description of the characteristic configuration of the present invention, the schematic configuration of the in-line four-cylinder premixed compression self-ignition engine 1 will be described. A premixed compression self-ignition engine 1 shown in the figure has a configuration in which a cylinder head 3 is attached to an upper part of a cylinder block 2 and a crankcase 4 is attached to a lower part of the cylinder block 2 as in an in-vehicle engine, for example. .

  The cylinder block 2 includes four cylinders 2a, 2b, 2c, and 2d arranged in series, and a water jacket 5 is provided so as to surround the cylinder liners of the cylinders 2a to 2d.

  Pistons 6A, 6B, 6C, and 6D are inserted into the cylinders 2a to 2d of the cylinder block 2, respectively. The pistons 6A to 6D are respectively connected to a crankshaft 7 disposed in the crankcase 4 and connected to a connecting rod 8A. , 8B, 8C, 8D. The four cylinders 2a to 2d, the four pistons 6A to 6D, and the cylinder head 3 of the cylinder block 2 form four independent combustion chambers 9A, 9B, 9C, and 9D.

  The intake port 3a, 3b, 3c, 3d of the cylinder head 3 has an intake surge tank 15 via individual intake pipes 15a, 15b, 15c, 15d, and an exhaust port 3e, 3f, 3g, Exhaust manifolds 16 are respectively attached to 3h. Intake valves 3A to 3d are provided with intake valves 17A, 17B, 17C and 17D, and exhaust ports 3e to 3h are provided with exhaust valves 18A, 18B, 18C and 18D, respectively. In the cylinder block 2, intake temperature sensors 19A, 19B, 19c, and 19D that detect the temperature of the air-fuel mixture flowing into the intake ports 3a to 3d are provided in the vicinity of the intake ports 3a to 3d. Further, although not shown, an exhaust pipe is attached to the exhaust manifold 16.

  In the intake path upstream of the intake surge tank 15, an air filter 21, a throttle 22, a mixer 23, and a heater 24 are provided in this order from the upstream side to the downstream side. The heater 24 may be a hot water heat exchanger using engine cooling water, an exhaust heat heat exchanger using exhaust heat, an electric heating element, or the like. A fuel supply path 25 is connected in communication with the mixer 23, and a gas injector 26 is provided in the fuel supply path 25. In short, air is taken in according to the opening degree of the throttle 22, this air is filtered by the air filter 21, and the filtered air and the fuel whose flow rate is controlled by the gas injector 26 are premixed by the mixer 23 to a predetermined ratio. The air-fuel mixture is heated to a predetermined temperature by the heater 24, then distributed by the intake surge tank 15, and supplied to the four combustion chambers 9A to 9D. Such a supply mode of the air-fuel mixture is called a simultaneous injection method.

  For each of the cylinders 2a to 2d, the first cylinders 2a and 2d in order from the most downstream side (the right side in FIGS. 1 and 2) to the upstream side (the left side in FIGS. 1 and 2) of the intake path. The number cylinder 2b, the number 3 cylinder 2c, and the number 4 cylinder 2d will be referred to. Similarly, the pistons 6A to 6D are also arranged in order from the most downstream side (right side in FIGS. 1 and 2) to the upstream side (left side in FIGS. 1 and 2) of the intake passage. No. 2 piston 6B, No. 3 piston 6C, No. 4 piston 6D, and each of the combustion chambers 9A to 9D is also upstream from the most downstream side (right side in FIG. 1 and FIG. 2) of the intake path (see FIG. 1 and FIG. 1). In order, toward the left side of FIG. 2, the first combustion chamber 9 </ b> A, the second combustion chamber 9 </ b> B, the third combustion chamber 9 </ b> C, and the fourth combustion chamber 9 </ b> D are provided. The first intake pipe 15a and the second intake pipe 15b are also sequentially arranged from the most downstream side (the right side in FIGS. 1 and 2) to the upstream side (the left side in FIGS. 1 and 2). The third intake pipe 15c and the fourth intake pipe 15d are referred to.

  The premixed compression self-ignition engine 1 is a four-cycle engine that repeats four steps of intake, compression, expansion, and exhaust, as is well known, and spontaneously ignites a premixed mixture with heat from compression. It is basically the same as a general 4-cycle engine except that it is made to do so.

  Briefly, in the intake stroke, the predetermined intake valves 17A to 17D are opened at a predetermined timing while lowering the predetermined pistons 6A to 6D, and the premixed air-fuel mixture is supplied to the predetermined combustion chambers 9A to 9D. In the compression stroke, the air-fuel mixture is compressed by raising the predetermined pistons 6A to 6D and decreasing the volumes of the predetermined combustion chambers 9A to 9D. However, the predetermined pistons 6A to 6D reach the top dead center (TDC). When rising, the air-fuel mixture ignites spontaneously and burns. In the expansion stroke, the predetermined pistons 6A to 6D are moved down to the bottom dead center (BDC) by the combustion, and in the exhaust stroke, the predetermined exhaust valves 18A to 18D are moved as the predetermined pistons 6A to 6D are raised. It opens and the combustion gas in predetermined combustion chamber 9A-9D is discharged | emitted.

  The premixed compression self-ignition engine 1 theoretically does not require an ignition plug, but in the first embodiment, the ignition plug 27A is located at a position corresponding to each cylinder 2a to 2d of the cylinder block 2 in the cylinder head 3. 27B, 27C, and 27D. The spark plugs 27A to 27D are used for facilitating ignition when the periphery of the combustion chambers 9A to 9D is not sufficiently warmed.

  Specifically, the premixed compression self-ignition engine 1 shown in the first embodiment performs [starting operation (warm-up operation)] → [operation by premixed compression self-ignition] → [operation when stopped]. It has become. In other words, ignition is performed using the spark plugs 27A to 27D during the start-up operation and the stop-time operation, and when the surroundings of the combustion chambers 9A to 9D reach a predetermined temperature or more due to the start-up operation, the operation by premixed compression self-ignition is performed. I have to.

  These operations will be briefly described. Although this operation is not described in detail, it is controlled by the controller 10.

  First, the premixed compression self-ignition engine 1 is started by a cell motor (not shown), and predetermined spark plugs 27A to 27D are energized to start the premixed compression self-ignition engine 1 by spark ignition. To warm up. In this warm-up operation, the temperature of the engine cooling water rises, and accordingly, the temperature of the air-fuel mixture to each of the combustion chambers 9A to 9D rises.

  As a result, when the predetermined intake temperature sensors 19A to 19D detect that the intake temperature of the air-fuel mixture has reached the establishment temperature of the premixed compression auto-ignition, the closing timing of the predetermined intake valves 17A to 17D is set to, for example, While advancing (advancing) to increase the compression ratio, the gas injector 26 is adjusted to increase the excess air ratio. When the compression ratio and the excess air ratio are switched, spontaneous ignition (compression auto-ignition) occurs, and when the combustion state by the premixed compression auto-ignition is detected by a knocking sensor (not shown) or the like, The ignition plugs 27A to 27D are turned off, the ignition by spark ignition is turned off, and the operation shifts to the premixed compression self-ignition operation.

  When stopping the premixed compression self-ignition operation, the spark plugs 27A to 27D are energized to turn on spark ignition, and the heating of the air-fuel mixture by the heater 24 is stopped. As a result, the intake temperature of the air-fuel mixture begins to drop. Next, for example, the closing timing of predetermined intake valves 17A to 17D in the advanced state is made backward to make the retarded state, and the gas injector 26 is adjusted to lower the excess air ratio. In this way, the air-fuel mixture supplied to the combustion chambers 9A to 9D is ignited by spark ignition by the predetermined spark plugs 27A to 27D, and after the ignition by the spark ignition is in a normal state, Reduce the engine speed and stop operation.

  Next, the characteristic configuration of the first embodiment will be described in detail with reference to FIGS. 2 and 3.

  In the first place, the self-ignition timing of the air-fuel mixture in the combustion chambers 9A to 9D deviates from a predetermined appropriate time due to the temperature change of the air-fuel mixture before being compressed in the combustion chambers 9A to 9D. In the case of multiple cylinders, the compression end temperatures of the combustion chambers 9A to 9D are likely to be uneven because the heat dissipation characteristics of the cylinders 2a to 2d are different due to the arrangement and structure of the cylinders 2a to 2d. The self-ignition timing of the air-fuel mixture in each of the combustion chambers 9A to 9D tends to vary.

  Incidentally, normally, the first cylinder 2a and the fourth cylinder 2d arranged at both ends in the longitudinal direction of the cylinder block 2 are superior in heat dissipation compared to the second cylinder 2b and the third cylinder 2c arranged in the middle in the longitudinal direction. Yes. Therefore, the compression end temperatures in the first combustion chamber 9A and the fourth combustion chamber 9D tend to be lower than the compression end temperatures in the second combustion chamber 9B and the third combustion chamber 9C, and thus the first combustion chamber 9A and the fourth combustion chamber 9D. The self-ignition timing of the air-fuel mixture tends to be later than the self-ignition timing of the air-fuel mixture in the second combustion chamber 9B and the third combustion chamber 9C. This is called variation in autoignition timing.

  Based on such knowledge, heaters 30A to 30D as heating means are individually attached to the outer peripheral surfaces of the four intake pipes 15a to 15d provided in the intake surge tank 15, and the heaters 30A to 30D are individually attached by the controller 10. It is configured so that it can be controlled.

  The heaters 30A to 30D are, for example, electric heating elements. Other examples include a hot water heat exchanger that uses engine cooling water, an exhaust heat heat exchanger that uses exhaust heat, and the like. The heaters 30A to 30D made of this electric heating element are cylindrical or sheet-like, and are attached so as to be fitted or wound around the outer peripheral surfaces of the intake pipes 15a to 15d.

  Based on the detection output for each of the intake air temperature sensors 19A to 19D, the controller 10 individually feedback-controls each of the heaters 30A to 30D so that the detection outputs for each of the intake air temperature sensors 19A to 19D match or substantially match. Of course, the controller 10 may perform feedforward control of the heaters 30A to 30D individually in consideration of various conditions, or may perform control in which both controls are combined.

  Specifically, the heating for the first intake pipe 15a and the fourth intake pipe 15d located at both ends in the longitudinal direction of the cylinder block 2 is compared with the heating for the second intake pipe 15c and the third intake pipe 15d located in the middle in the longitudinal direction. The controller 10 controls so as to make it stronger.

  In this case, by heating the first intake pipe 15a and the fourth intake pipe 15d, the temperature of the air-fuel mixture passing through the first intake pipe 15a and the fourth intake pipe 15d can be increased. A difference can be made between the temperature of the air-fuel mixture passing through the intake pipe 15a and the fourth air intake pipe 15d and the temperature of the air-fuel mixture passing through the second cylinder 2b and the third cylinder 2c.

  Due to the temperature difference between the mixture supplied to the first combustion chamber 9A and the fourth combustion chamber 9D and the mixture supplied to the second combustion chamber 9B and the third combustion chamber 9C, the first cylinder 2a and It is possible to cancel the temperature difference between the fourth cylinder 2d and the second and second cylinders 2b and 2c, which are relatively difficult to dissipate heat.

  Therefore, by adjusting the temperature difference of the air-fuel mixture, the compression end temperatures of the first combustion chamber 9A and the fourth combustion chamber 9D are matched based on the compression end temperatures of the second combustion chamber 9B and the third combustion chamber 9C. Like that. Thereby, since the compression end temperature for every combustion chamber 9A-9D can be equalized, the dispersion | variation in the self-ignition timing in every combustion chamber 9A-9D can be reduced. Therefore, cycle efficiency and thermal efficiency can be improved, and knocking and misfire can be avoided and NOx generation can be reduced.

  Hereinafter, application examples of the first embodiment will be described.

  The heaters 30 </ b> A to 30 </ b> D as the heating means may be provided inside the four intake pipes 15 a to 15 d of the intake surge tank 15.

  As an example, as shown in FIGS. 4 and 5, four heaters 30A to 30D are used as heating means. The heaters 30A to 30D are comb-shaped electric heating elements. A plurality of rod-like portions provided in the heaters 30A to 30D are made to enter from the outside into the four intake pipes 15a to 15d, respectively.

  As another example, as shown in FIGS. 6 and 7, eight heaters 30A to 30H are used as heating means. The heaters 30A to 30H are comb-shaped electric heating elements. The heaters 30A to 30H are set in pairs, and a plurality of rod-like portions in each set of heaters 30A to 30H are respectively plunged into the four intake pipes 15a to 15d in a state of being orthogonally crossed from the outside.

  In any of the above examples, substantially the same operations and effects as in the first embodiment can be obtained. Furthermore, the kind of heater 30A-30H used in such a structure is not specifically limited.

  In the first embodiment and the application examples related thereto (FIGS. 4 to 7), the heaters 30A to 30H for the first intake pipe 15a, the second intake pipe 15b, the third intake pipe 15c, and the fourth intake pipe 15d, respectively. By individually adjusting the heating amount, the temperature of the air-fuel mixture passing through the intake pipes 15a to 15d can be individually finely adjusted. In this case, the compression end temperature for each of the combustion chambers 9A to 9D can be more accurately aligned.

  Further, in the first embodiment and application examples (FIGS. 4 to 7) related thereto, the heaters 30A to 30H are individually attached to all of the four intake pipes 15a to 15d. The heating means as described above may be attached only to the 15a and the fourth intake pipe 15d.

<Embodiment 2>
With reference to FIG. 8, Embodiment 2 of the multi-cylinder type premixed compression self-ignition engine 1 according to the present invention will be described. Note that the basic configuration of the premixed compression self-ignition engine 1 is the same as that of the first embodiment, and the description thereof is omitted here.

  In the second embodiment, among the four intake pipes 15a to 15d, only the first intake pipe 15a located on the most downstream side of the intake path and the fourth intake pipe 15d located on the most upstream side of the intake path are insulated. It is characterized in that 31 is coated.

  In this case, the heat insulation action of the heat insulating material 31 improves the heat retention of the first intake pipe 15a and the fourth intake pipe 15d, so that the temperature drop of the air-fuel mixture passing through the first intake pipe 15a and the fourth intake pipe 15d is reduced. This can be suppressed as compared with the temperature drop of the air-fuel mixture passing through the second cylinder 2b and the third cylinder 2c. Thereby, the temperature of the air-fuel mixture passing through the first intake pipe 15a and the fourth air intake pipe 15d can be differentiated from the temperature of the air-fuel mixture passing through the second cylinder 2b and the third cylinder 2c.

  Due to the temperature difference between the mixture supplied to the first combustion chamber 9A and the fourth combustion chamber 9D and the mixture supplied to the second combustion chamber 9B and the third combustion chamber 9C, the first cylinder 2a and It is possible to cancel the temperature difference between the fourth cylinder 2d and the second and second cylinders 2b and 2c, which are relatively difficult to dissipate heat.

  Therefore, by adjusting the temperature difference of the air-fuel mixture, the compression end temperatures of the first combustion chamber 9A and the fourth combustion chamber 9D are matched based on the compression end temperatures of the second combustion chamber 9B and the third combustion chamber 9C. Like that. Thereby, since the compression end temperature for every combustion chamber 9A-9D can be equalized, the dispersion | variation in the self-ignition timing in every combustion chamber 9A-9D can be reduced. Therefore, cycle efficiency and thermal efficiency can be improved, and knocking and misfire can be avoided and NOx generation can be reduced.

  In addition, the thickness and covering length range of the heat insulating material 31 correspond to specifications such as the material of the cylinder block 2, the material of the intake pipes 15a to 15d, the interval between the cylinders 2a to 2d, the thickness of the cylinder block 2, and the like. It is preferable to set appropriately considering the heat radiation characteristics of each part.

  Hereinafter, application examples of the second embodiment will be described.

  First, you may make it coat | cover the heat insulating material 31 to all the four intake pipes 15a-15d. However, in that case, the heat dissipation characteristics for each of the intake pipes 15a to 15d are appropriately adjusted by individually adjusting the covering state for each heat insulating material 31 with respect to each of the intake pipes 15a to 15d, that is, the thickness and the covering length range for each heat insulating material 31. Need to be adjusted individually.

  As an example, as shown in FIG. 9, among the four intake pipes 15a to 15d provided in the intake surge tank 15, the thicknesses t1 and t4 of the heat insulating material 31 covering the first intake pipe 15a and the fourth intake pipe 15d. Can be set thicker than the thicknesses t2 and t3 of the heat insulating material 31 covering the second intake pipe 15b and the third intake pipe 15c.

  As another example, as shown in FIG. 10, the covering length ranges L1 and L4 of the heat insulating material 31 covering the first intake pipe 15a and the fourth intake pipe 15d are changed to the second intake pipe 15b and the third intake pipe. It can be set larger than the covering length ranges L2 and L3 of the heat insulating material 31 covering 15c.

  In this way, since the heat radiation characteristics in the intake pipes 15a to 15d can be finely managed, the compression end temperatures for the combustion chambers 9A to 9D can be made even more accurate.

<Embodiment 3>
With reference to FIG. 11, Embodiment 3 of the multi-cylinder premixed compression self-ignition engine 1 according to the present invention will be described. Note that the basic configuration of the premixed compression self-ignition engine 1 is the same as that of the first embodiment, and the description thereof is omitted here.

  The third embodiment is characterized in that the second intake pipe 15b and the third intake pipe 15c have higher thermal conductivity than the first intake pipe 15a and the fourth intake pipe 15d.

  Specifically, when the first intake pipe 15a and the fourth intake pipe 15d are made of an iron-based metal generally used, the second intake pipe 15b and the third intake pipe 15c are made of an aluminum alloy. Combinations of other materials are also possible, and the metal used as the base of each of the intake pipes 15a to 15d can be the same, and the composition can be individually adjusted.

  In this case, since the heat dissipation of the second intake pipe 15b and the third intake pipe 15c is improved as compared with the first intake pipe 15a and the fourth intake pipe 15d, the air-fuel mixture passing through the second cylinder 2b and the third cylinder 2c The temperature decrease is promoted compared to the temperature decrease of the air-fuel mixture passing through the first intake pipe 15a and the fourth intake pipe 15d. Thereby, the temperature of the air-fuel mixture passing through the second cylinder 2b and the third cylinder 2c can be differentiated from the temperature of the air-fuel mixture passing through the first intake pipe 15a and the fourth intake pipe 15d.

  Due to the temperature difference between the mixture supplied to the first combustion chamber 9A and the fourth combustion chamber 9D and the mixture supplied to the second combustion chamber 9B and the third combustion chamber 9C, the first cylinder 2a and It is possible to cancel the temperature difference between the fourth cylinder 2d and the second and second cylinders 2b and 2c, which are relatively difficult to dissipate heat.

  Therefore, by adjusting the temperature difference of the air-fuel mixture, the compression end temperatures of the second combustion chamber 9B and the third combustion chamber 9C are matched based on the compression end temperatures of the first combustion chamber 9A and the fourth combustion chamber 9D. Like that. Thereby, since the compression end temperature for every combustion chamber 9A-9D can be equalized, the dispersion | variation in the self-ignition timing in every combustion chamber 9A-9D can be reduced. Therefore, cycle efficiency and thermal efficiency can be improved, and knocking and misfire can be avoided and NOx generation can be reduced.

  Hereinafter, application examples of the third embodiment will be described.

  Contrary to the above, the first intake pipe 15a and the fourth intake pipe 15d may have lower thermal conductivity than the second intake pipe 15b and the third intake pipe 15c. In this case, since the heat retaining properties of the first intake pipe 15a and the fourth intake pipe 15d are improved as compared with the second intake pipe 15b and the third intake pipe 15c, mixing through the first intake pipe 15a and the fourth intake pipe 15d is performed. The temperature drop of the gas can be suppressed as compared with the temperature drop of the air-fuel mixture passing through the second cylinder 2b and the third cylinder 2c. Due to the temperature difference between the mixture supplied to the first combustion chamber 9A and the fourth combustion chamber 9D and the mixture supplied to the second combustion chamber 9B and the third combustion chamber 9C, the first cylinder 2a and It is possible to cancel the temperature difference between the fourth cylinder 2d and the second and second cylinders 2b and 2c, which are relatively difficult to dissipate heat. Therefore, by adjusting the temperature difference of the air-fuel mixture, the compression end temperatures of the first combustion chamber 9A and the fourth combustion chamber 9D are matched based on the compression end temperatures of the second combustion chamber 9B and the third combustion chamber 9C. Like that. Thereby, since the compression end temperature for every combustion chamber 9A-9D can be arrange | equalized, the same effect as the above is acquired.

  Although not shown, the material and composition are specified so that the thermal conductivity of each of the first intake pipe 15a, the second intake pipe 15b, the third intake pipe 15c, and the fourth intake pipe 15d is individually adjusted. Thus, the heat dissipation characteristics in the intake pipes 15a to 15d can be finely managed. In this case, the compression end temperature for each of the combustion chambers 9A to 9D can be made even more accurate.

<Embodiment 4>
A fourth embodiment of a multi-cylinder premixed compression self-ignition engine 1 according to the present invention will be described with reference to FIGS. Note that the basic configuration of the premixed compression self-ignition engine 1 is the same as that of the first embodiment, and the description thereof is omitted here.

  The fourth embodiment is characterized in that the radiating fins 32 are provided integrally or separately on the outer circumferences of the second intake pipe 15b and the third intake pipe 15c.

  Specifically, with the radiation fins 32 as a plurality of plate pieces, the radiation fins 32 are arranged in the direction along the hole center axis of the second intake pipe 15b and the third intake pipe 15c and are arranged side by side in the circumferential direction. I try to install it.

  In addition, for example, as shown in FIGS. 14 and 15, the radiating fins 32 are arranged in a direction orthogonal to the hole center axis of the second intake pipe 15b and the third intake pipe 15c and are adjacent to each other along the hole center axis. You may make it attach in the state which arranged.

  In this case, the radiation area of the second intake pipe 15b and the third intake pipe 15c is larger than that of the first intake pipe 15a and the fourth intake pipe 15d by the radiation fins 32, so that the second cylinder 2b and the third cylinder 2c Heat can be efficiently dissipated from the second intake pipe 15b and the third intake pipe 15c.

  As described above, since the heat radiation performance of the second intake pipe 15b and the third intake pipe 15c is improved as compared with the first intake pipe 15a and the fourth intake pipe 15d, the air-fuel mixture passing through the second cylinder 2b and the third cylinder 2c. The temperature drop is promoted compared to the temperature drop of the air-fuel mixture passing through the first intake pipe 15a and the fourth intake pipe 15d. Thereby, the temperature of the air-fuel mixture passing through the second cylinder 2b and the third cylinder 2c can be differentiated from the temperature of the air-fuel mixture passing through the first intake pipe 15a and the fourth intake pipe 15d.

  Due to the temperature difference between the mixture supplied to the first combustion chamber 9A and the fourth combustion chamber 9D and the mixture supplied to the second combustion chamber 9B and the third combustion chamber 9C, the first cylinder 2a and It is possible to cancel the temperature difference between the fourth cylinder 2d and the second and second cylinders 2b and 2c, which are relatively difficult to dissipate heat.

  Therefore, by adjusting the temperature difference of the air-fuel mixture, the compression end temperatures of the second combustion chamber 9B and the third combustion chamber 9C are matched based on the compression end temperatures of the first combustion chamber 9A and the fourth combustion chamber 9D. Like that. Thereby, since the compression end temperature for every combustion chamber 9A-9D can be equalized, the dispersion | variation in the self-ignition timing in every combustion chamber 9A-9D can be reduced. Therefore, cycle efficiency and thermal efficiency can be improved, and knocking and misfire can be avoided and NOx generation can be reduced.

  Hereinafter, application examples of the fourth embodiment will be described.

  Although not shown in the figure, the radiating fins 32 are provided on all the four intake pipes 15a to 15d, and then the first intake pipe 15a, the second intake pipe 15b, the third intake pipe 15c, and the fourth intake pipe 15d are respectively provided. By individually adjusting the number and size of the radiating fins 32, it is possible to finely manage the radiating characteristics of the intake pipes 15a to 15d. In this case, the compression end temperature for each of the combustion chambers 9A to 9D can be made even more accurate.

<Embodiment 5>
A fifth embodiment of a multi-cylinder premixed compression self-ignition engine 1 according to the present invention will be described with reference to FIGS. 16 and 17. Note that the basic configuration of the premixed compression self-ignition engine 1 is the same as that of the first embodiment, and the description thereof is omitted here.

  The fifth embodiment is characterized in that the cooling water passage 33 is provided in the second intake pipe 15b and the third intake pipe 15c, and the engine cooling water is caused to flow through the cooling water passage 33.

  Specifically, a cooling water passage 33 including a through hole is provided in the tubular wall portion forming the second intake pipe 15b and the third intake pipe 15c, and the cooling water passage 33 communicates with the water jacket 5 of the cylinder block 2. I try to connect them.

  In this case, since the second intake pipe 15b and the third intake pipe 15c can be cooled with the cooling water, the temperature drop of the air-fuel mixture passing through the second cylinder 2b and the third cylinder 2c is caused by the first intake pipes 15a and 4 This is promoted compared to the temperature drop of the air-fuel mixture passing through the intake pipe 15d. Thereby, the temperature of the air-fuel mixture passing through the second cylinder 2b and the third cylinder 2c can be differentiated from the temperature of the air-fuel mixture passing through the first intake pipe 15a and the fourth intake pipe 15d.

  Due to the temperature difference between the mixture supplied to the first combustion chamber 9A and the fourth combustion chamber 9D and the mixture supplied to the second combustion chamber 9B and the third combustion chamber 9C, the first cylinder 2a and It is possible to cancel the temperature difference between the fourth cylinder 2d and the second and second cylinders 2b and 2c, which are relatively difficult to dissipate heat.

  Therefore, by adjusting the temperature difference of the air-fuel mixture, the compression end temperatures of the second combustion chamber 9B and the third combustion chamber 9C are matched based on the compression end temperatures of the first combustion chamber 9A and the fourth combustion chamber 9D. Like that. Thereby, since the compression end temperature for every combustion chamber 9A-9D can be equalized, the dispersion | variation in the self-ignition timing in every combustion chamber 9A-9D can be reduced. Therefore, cycle efficiency and thermal efficiency can be improved, and knocking and misfire can be avoided and NOx generation can be reduced.

  Hereinafter, application examples of the fifth embodiment will be described.

  Although not shown, a pipe body that becomes the cooling water passage 33 may be attached to the outer peripheral surface or the inner peripheral surface of the tubular wall portion that forms the second intake pipe 15b and the third intake pipe 15c. In this case, all the intake pipes 15a to 15d can be made the same, and it is only necessary to attach the pipe body that becomes the cooling water passage 33, so that the manufacturing cost can be reduced.

  Although not shown, the first intake pipe 15a, the second intake pipe 15b, the third intake pipe 15c, and the fourth intake pipe are provided after the cooling water passages 33 are provided in all of the four intake pipes 15a to 15d. By individually adjusting the flow rate of the cooling water for each of 15d, the heat dissipation characteristics of each of the intake pipes 15a to 15d can be finely managed. In this case, the compression end temperature for each of the combustion chambers 9A to 9D can be made even more accurate.

  As an example, as shown in FIGS. 18 and 19, the cooling water passages 33 are provided in all the intake pipes 15 a to 15 d, and the cooling water passages 33 are appropriately communicated with the water jacket 5 of the cylinder block 2. Thus, the water amount adjusting valve 34 can be individually provided on the inlet side of each cooling water passage 33.

  In this case, the opening degree of each water amount adjustment valve 34 is controlled by the controller 10. Based on the detection outputs from the intake air temperature sensors 19A to 19D, the controller 10 individually feedback-controls each water amount adjustment valve 34 so that the detection outputs from the intake air temperature sensors 19A to 19D are matched or substantially matched. be able to. Of course, the controller 10 may be configured to individually feed forward control each water amount adjusting valve 34 in consideration of various conditions, or may perform control in which both controls are combined.

<Embodiment 6>
Referring to FIG. 20, a sixth embodiment of the multi-cylinder premixed compression self-ignition engine 1 according to the present invention will be described. Note that the basic configuration of the premixed compression self-ignition engine 1 is the same as that of the first embodiment, and the description thereof is omitted here.

  The sixth embodiment is characterized in that the second piston 6B and the third piston 6C have higher thermal conductivity than the first piston 6A and the fourth piston 6D.

  Specifically, when the 1st piston 6A and the 4th piston 6D are made of iron-based metal, preferably ductile cast iron, the 2nd piston 6B and the 3rd piston 6C are made of an aluminum alloy. Combinations of other materials are also possible, and the metal used as the base of each of the pistons 6A to 6D can be the same, and the composition can be individually adjusted.

  In this case, since the heat of the second piston 6B and the third piston 6C can be easily conducted to the cylinder block 2, the heat dissipation of the second cylinder 2b and the third cylinder 2c can be improved. As a result, the temperatures of the second cylinder 2b and the third cylinder 2c can be matched with the temperatures of the first cylinder 2a and the fourth cylinder 2d.

  Therefore, by adjusting the heat dissipation of the piston, the temperatures of the second cylinder 2b and the third cylinder 2c are matched with respect to the temperatures of the first cylinder 2a and the fourth cylinder 2d. Thereby, since the compression end temperature for every combustion chamber 9A-9D can be equalized, the dispersion | variation in the self-ignition timing in every combustion chamber 9A-9D can be reduced. Therefore, cycle efficiency and thermal efficiency can be improved, and knocking and misfire can be avoided and NOx generation can be reduced.

  Hereinafter, application examples of the sixth embodiment will be described.

  Contrary to the above, the first piston 6A and the fourth piston 6D can have a lower thermal conductivity than the second piston 6B and the third piston 6C. In this case, the heat of the first piston 6A and the fourth piston 6D can be hardly conducted to the first cylinder 2a and the fourth cylinder 2d, so that the heat dissipation of the first cylinder 2a and the fourth cylinder 2d can be reduced. Become. Therefore, the temperatures of the first cylinder 2a and the fourth cylinder 2d can be matched based on the temperatures of the second cylinder 2b and the third cylinder 2c, so that the compression end temperatures of the combustion chambers 9A to 9D are made uniform. Is possible. As a result, the same effect as described above can be obtained.

  Moreover, although not shown in figure, the material and composition of each piston 6A-6D are specified so that the thermal conductivity of each of 1st piston 6A, 2nd piston 6B, 3rd piston 6C, 4th piston 6D may be set individually. This makes it possible to align the temperatures in the combustion chambers 9A to 9D with higher accuracy.

<Embodiment 7>
A seventh embodiment of the multi-cylinder premixed compression self-ignition engine 1 according to the present invention will be described with reference to FIG. Note that the basic configuration of the premixed compression self-ignition engine 1 is the same as that of the first embodiment, and the description thereof is omitted here.

  The seventh embodiment is characterized in that the top portions of the first piston 6A and the fourth piston 6D are formed of a material having a lower thermal conductivity than the body portion.

  Specifically, the first piston 6A and the fourth piston 6D are formed of a commonly used aluminum alloy, and the top portion thereof is coated with a material having a low thermal conductivity, such as alumite, ceramics, etc. . The coating film is denoted by reference numeral 35.

  According to this configuration, since the amount of heat released from the first piston 6A and the fourth piston 6D can be reduced by the coating film 35, the first cylinder 2a and the fourth cylinder 2d can be made difficult to dissipate heat. .

  Therefore, the heat dissipation characteristics of the first cylinder 2a and the fourth cylinder 2d can be matched based on the heat dissipation characteristics of the second cylinder 2b and the third cylinder 2c, so that the compression end temperature for each of the combustion chambers 9A to 9D can be adjusted. It becomes possible to align.

  Therefore, since variation in the self-ignition timing of the air-fuel mixture in each of the combustion chambers 9A to 9D can be reduced, cycle efficiency and thermal efficiency can be improved, and knocking and misfire can be avoided and NOx generation can be reduced.

  Hereinafter, application examples of the seventh embodiment will be described.

  First, instead of the coating film 35, a member made of a material having low thermal conductivity may be attached to the tops of the first piston 6A and the fourth piston 6D by adhesion or the like.

  Moreover, the 1st piston 6A and the 4th piston 6D can be made into the assembly piston which made the trunk | drum part and the top part separate, and a top part can be formed with a material with low heat conductivity.

<Eighth embodiment>
With reference to FIGS. 22 and 23, an eighth embodiment of the multi-cylinder premixed compression self-ignition engine 1 according to the present invention will be described. Note that the basic configuration of the premixed compression self-ignition engine 1 is the same as that of the first embodiment, and the description thereof is omitted here.

  The eighth embodiment is characterized in that a heat insulating portion 36 is provided inside the first piston 6A and the fourth piston 6D.

  Specifically, the heat insulating portion 36 is a circular hole-shaped cavity formed in an annular shape in the outer peripheral thick portion on the top side of the first piston 6A and the fourth piston 6D, for example.

  According to this configuration, since the heat conductivity of the first piston 6A and the fourth piston 6D is lowered by the heat insulating portion 36 formed of a cavity provided in the first piston 6A and the fourth piston 6D, it is difficult to cool down. It becomes possible to make it difficult to dissipate heat in the 2a and 4th cylinders 2d.

  Therefore, the heat dissipation characteristics of the first cylinder 2a and the fourth cylinder 2d can be matched based on the heat dissipation characteristics of the second cylinder 2b and the third cylinder 2c, so that the compression end temperature for each of the combustion chambers 9A to 9D can be adjusted. It becomes possible to align.

  Therefore, since variation in the self-ignition timing of the air-fuel mixture in each of the combustion chambers 9A to 9D can be reduced, cycle efficiency and thermal efficiency can be improved, and knocking and misfire can be avoided and NOx generation can be reduced.

  By the way, if the weight is reduced by providing the heat insulating portion 36 formed of a cavity in the first piston 6A and the fourth piston 6D, the first piston 6A is expected to be lightened by the heat insulating portion 36 formed of a cavity. It is preferable that the weights of the pistons 6 </ b> A to 6 </ b> D are made substantially uniform by adjusting the weight balance by forming the fourth piston 6 </ b> D with a material having a heavy mass.

<Ninth Embodiment>
Referring to FIG. 24, a ninth embodiment of the multi-cylinder premixed compression self-ignition engine 1 according to the present invention will be described. Note that the basic configuration of the premixed compression self-ignition engine 1 is the same as that of the first embodiment, and the description thereof is omitted here.

  In the ninth embodiment, an oil supply path 37 and oil jet injectors 38A to 38D for individually injecting and cooling oil to the pistons 6A to 6D are provided, and the oil injection amounts by the oil jet injectors 38A to 38D are provided. Is characterized by being individually controlled.

  Specifically, the oil injection amounts to the second piston 6B and the third piston 6C by the oil jet injectors 38B and 38C are changed to the oil injection amounts to the first piston 6A and the fourth piston 6D by the oil jet injectors 38A and 38D, respectively. By setting more, the second piston 6B and the third piston 6C are more easily cooled than the first piston 6A and the fourth piston 6D. As a result, it is possible to make it difficult for the second cylinder 2b and the third cylinder 2c to generate heat.

  Therefore, the heat dissipation characteristics of the second cylinder 2b and the third cylinder 2c can be matched based on the heat dissipation characteristics of the first cylinder 2a and the fourth cylinder 2d, so that the compression end temperature for each of the combustion chambers 9A to 9D can be set. It becomes possible to align.

  Therefore, since variation in the self-ignition timing of the air-fuel mixture in each of the combustion chambers 9A to 9D can be reduced, cycle efficiency and thermal efficiency can be improved, and knocking and misfire can be avoided and NOx generation can be reduced.

  Hereinafter, application examples of the ninth embodiment will be described.

  For example, the oil injection amount to the first piston 6A and the fourth piston 6D by the oil jet injectors 38A and 38D is larger than the oil injection amount to the second piston 6B and the third piston 6C by the oil jet injectors 38B and 38C. You may set few. In this case, the first piston 6A and the fourth piston 6D can be made more difficult to cool than the second piston 6B and the third piston 6C. In this case, since the heat dissipation characteristics of the first cylinder 2a and the fourth cylinder 2d can be matched based on the heat dissipation characteristics of the second cylinder 2b and the third cylinder 2c, the same effect as described above can be obtained.

  Also, as shown in FIG. 25, the oil jet injectors 38A and 38D corresponding to the second piston 6B and the third piston 6C are eliminated without the oil jet injectors 38A and 38D corresponding to the first piston 6A and the fourth piston 6D. Only 38C may be provided, and only the second piston 6B and the third piston 6C may be cooled by appropriately performing oil jet injection. In this case, the same effect as described above can be obtained with a relatively simple configuration.

<Embodiment 10>
A tenth embodiment of a multi-cylinder premixed compression self-ignition engine 1 according to the present invention will be described with reference to FIG. Note that the basic configuration of the premixed compression self-ignition engine 1 is the same as that of the first embodiment, and the description thereof is omitted here.

  The tenth embodiment is characterized in that cooling water having a constant temperature is always introduced into the water jacket 5 of the cylinder block 2.

  Specifically, a cooling water inlet 5 a for introducing cooling water into the water jacket 5 is provided on the surface on one end side in the longitudinal direction of the cylinder block 2 (surface on the fourth cylinder 2 d side). A cooling water outlet 5b for leading out the cooling water in the water jacket 5 of the cylinder block 2 is provided on the surface on one end side in the longitudinal direction (the surface on the fourth cylinder 2d side). Then, the cooling water introduced into the water jacket 5 from the cooling water inlet 5a cools the cylinder liner constituting each of the cylinders 2a to 2d, then flows to the cylinder head 3 side, and is discharged from the cooling water outlet 5b. Is done. The discharged cooling water is circulated so as to be introduced again into the cooling water inlet 5a.

  Although the cooling water is circulated in this way, the temperature of the cooling water discharged from the cooling water outlet 5b is increased by absorbing the heat of the cylinder block 2 and the cylinder head 3, so that the temperature adjusting device 40 The temperature is adjusted to a predetermined temperature and then introduced into the cooling water inlet 5a.

  The temperature adjustment device 40 has a configuration in which a heat exchanger 42 is disposed inside a container 41. A cooling water inlet 5 a and a cooling water outlet 5 b are connected to the container 41 through flowing water channels 43 and 44. Further, a temperature control valve 45 is provided at the cooling water inlet 5 a of the cylinder block 2. The temperature adjustment valve 45 controls the temperature of the cooling water introduced into the water jacket 5 by controlling the amount of water that is introduced when the cooling water whose temperature has been adjusted by the temperature adjustment device 40 is introduced into the water jacket 5 of the cylinder block 2. Keep it constant.

  Incidentally, since the temperature control valve 45 is conventionally provided at the cooling water outlet 5b of the cylinder head 3, the temperature of the cooling water introduced into the water jacket 5 of the cylinder block 2 may vary, There is a possibility that the compression end temperature for each combustion chamber 9A to 9D may vary for each engine operation cycle, for example, the amount of heat absorbed by the cooling water from the cylinder liner constituting the cylinders 2a to 2d tends to vary for each engine operation cycle. .

  On the other hand, in the tenth embodiment, the temperature of the cooling water introduced into the water jacket 5 can always be kept substantially constant regardless of the engine operation cycle, so that the cylinder liners that constitute the four cylinders 2a to 2d are used. The amount of heat absorbed by the cooling water can be made substantially equal regardless of the engine operation cycle. Therefore, the compression end temperatures for the combustion chambers 9A to 9D can be made substantially equal regardless of the engine operation cycle. Therefore, since variation in the self-ignition timing of the air-fuel mixture in each of the combustion chambers 9A to 9D can be reduced, cycle efficiency and thermal efficiency can be improved, and knocking and misfire can be avoided and NOx generation can be reduced.

  By the way, it is preferable to set the temperature of the cooling water introduced into the water jacket 5 of the cylinder block 2 to 80 ° C. to 90 ° C. As described above, when the temperature of the cooling water introduced into the water jacket 5 is set higher than usual, the heat exchange amount between the first cylinder 2a and the fourth cylinder 2d is changed to the heat exchange between the second cylinder 2b and the third cylinder 2c. Since the amount can be reduced as compared with the amount, the temperature of the cylinder liner constituting the first cylinder 2a and the fourth cylinder 2d is hardly lowered. In particular, since the difference between the temperature of the cylinder liner constituting the first cylinder 2a and the fourth cylinder 2d and the mixture temperature supplied into the first combustion chamber 9A and the fourth combustion chamber 9D can be reduced, It becomes possible to arrange the compression end temperatures for each of the combustion chambers 9A to 9D.

<Embodiment 11>
With reference to FIG. 27, an eleventh embodiment of a multi-cylinder premixed compression self-ignition engine 1 according to the present invention will be described. Note that the basic configuration of the premixed compression self-ignition engine 1 is the same as that of the first embodiment, and the description thereof is omitted here.

  The eleventh embodiment is characterized in that the second cylinder 2b and the third cylinder 2c are preferentially cooled with engine cooling water.

  Specifically, the cooling water for introducing the cooling water to the water jacket 5 between the second cylinder 2b and the third cylinder 2c on the surface on one side in the short direction of the cylinder block 2 (the surface on the exhaust manifold 16 side). While providing the introduction port 5 a, the coolant outlet port 5 b is provided on the surface on the one end side in the longitudinal direction of the cylinder head 3 (the surface on the fourth cylinder 2 d side). Although not shown, the temperature adjusting device 40 described in the tenth embodiment is connected to the cooling water inlet 5a and the cooling water outlet 5b.

  According to such a configuration, the cooling water is introduced from the cooling water introduction port 5a between the second cylinder 2b and the third cylinder 2c in the water jacket 5, and then the first cylinder 2a and the fourth cylinder 2d side. And then flows to the back side of the first cylinder 2a and the fourth cylinder 2d, then flows to the cylinder head 3 side, and is sent from the cooling water outlet 5b to the temperature adjusting device side (not shown).

  Thus, the temperature of the cooling water when cooling the second cylinder 2b and the third cylinder 2c is lower than the temperature of the cooling water when cooling the first cylinder 2a and the fourth cylinder 2d. The cooling capacity of the cylinder 2b and the third cylinder 2c can be increased as compared with the cooling capacity of the first cylinder 2a and the fourth cylinder 2d.

  Therefore, the heat dissipation characteristics of the second cylinder 2b and the third cylinder 2c can be matched based on the heat dissipation characteristics of the first cylinder 2a and the fourth cylinder 2d, so that the compression end temperature for each of the combustion chambers 9A to 9D can be set. It becomes possible to align. Therefore, since variation in the self-ignition timing of the air-fuel mixture in each of the combustion chambers 9A to 9D can be reduced, cycle efficiency and thermal efficiency can be improved, and knocking and misfire can be avoided and NOx generation can be reduced.

  Incidentally, as shown in FIG. 28, the head gasket 11 interposed between the cylinder block 2 and the cylinder head 3 is formed in a rectangular plate shape as viewed from above, and is arranged in a line in the longitudinal direction 4. Four through holes 11a to 11d corresponding to the two cylinders 2a to 2d are provided, and the water jacket 5 and the cylinder head 3 of the cylinder block 2 are not shown around the through holes 11a to 11d. Ten cooling water passage holes 11e to 11n communicating with the cooling water passage are provided. Incidentally, although not shown in the figure, the conventional head gasket has a cooling water passage hole provided at the center in the short direction at both ends in the longitudinal direction, so that a cylinder block is provided around the first cylinder 2a and the fourth cylinder 2d. The flow rate of the coolant flowing from 2 to the cylinder head 3 side is larger than that of the second cylinder 2b and the third cylinder 2c, and the first cylinder 2a and the fourth cylinder 2d are easily cooled. On the other hand, when the head gasket 11 shown in FIG. 28 is used, all the cylinders 2a to 2d are cooled substantially uniformly, which is advantageous in making the compression end temperatures uniform for the combustion chambers 9A to 9D. Become.

<Twelfth embodiment>
Referring to FIG. 29, a twelfth embodiment of the multi-cylinder premixed compression self-ignition engine 1 according to the present invention will be described. Note that the basic configuration of the premixed compression self-ignition engine 1 is the same as that of the first embodiment, and the description thereof is omitted here.

  In the twelfth embodiment, the coolant flow rate to the peripheral portions of the second cylinder 2b and the third cylinder 2c is made larger than the coolant flow rate to the peripheral portions of the first cylinder 2a and the fourth cylinder 2d. There are features.

  Specifically, the thicknesses X2 and X3 of the cylinder liners constituting the second cylinder 2b and the third cylinder 2c are larger than the thicknesses X1 and X4 of the cylinder liners constituting the first cylinder 2a and the fourth cylinder 2d. By setting it thin, the width (width in the short direction of the cylinder block 2) W2 and W3 of the peripheral portion of the second cylinder 2b and the third cylinder 2c in the water jacket 5 are set to the first cylinders 2a and 4 in the water jacket 5. The width of the peripheral portion of the number cylinder 2d (width in the short direction of the cylinder block 2) is made wider than W1 and W4.

  According to this configuration, the coolant flow rate to the peripheral portions of the second cylinder 2b and the third cylinder 2c in the water jacket 5 is the coolant flow rate to the peripheral portions of the first cylinder 2a and the fourth cylinder 2d in the water jacket 5. Therefore, the cooling capacity of the second cylinder 2b and the third cylinder 2c can be increased as compared with the cooling capacity of the first cylinder 2a and the fourth cylinder 2d. Therefore, the second cylinder 2b and the third cylinder 2c can be radiated easily.

  Therefore, the heat dissipation characteristics of the second cylinder 2b and the third cylinder 2c can be matched based on the heat dissipation characteristics of the first cylinder 2a and the fourth cylinder 2d, so that the compression end temperature for each of the combustion chambers 9A to 9D can be set. It becomes possible to align. Therefore, since variation in the self-ignition timing of the air-fuel mixture in each of the combustion chambers 9A to 9D can be reduced, cycle efficiency and thermal efficiency can be improved, and knocking and misfire can be avoided and NOx generation can be reduced.

  Hereinafter, application examples of the twelfth embodiment will be described.

  Although not shown, conversely to the above, the width of the peripheral portion of the water jacket 5 around the first cylinder 2a and the fourth cylinder 2d (the width in the short direction of the cylinder block 2) is the second cylinder in the water jacket 5. You may set narrower than the width | variety (width of the transversal direction of the cylinder block 2) of the peripheral part of 2b and the 3rd cylinder 2c.

  In this case, the coolant flow rate to the peripheral portions of the first cylinder 2a and the fourth cylinder 2d in the water jacket 5 is less than the coolant flow rate to the peripheral portions of the second cylinder 2b and the third cylinder 2c in the water jacket 5. Therefore, the cooling capacity of the first cylinder 2a and the fourth cylinder 2d can be reduced more than the cooling capacity of the second cylinder 2b and the third cylinder 2c. This makes it difficult to dissipate heat from the first cylinder 2a and the fourth cylinder 2d. Therefore, it is possible to match the heat radiation characteristics of the first cylinder 2a and the fourth cylinder 2d with reference to the heat radiation characteristics of the second cylinder 2b and the third cylinder 2c, so that the same effect as described above can be obtained.

<Embodiment 13>
A thirteenth embodiment of a multi-cylinder premixed compression self-ignition engine 1 according to the present invention will be described with reference to FIG. The basic configuration of the premixed compression self-ignition engine 1 is the same as that of the first embodiment, and the description thereof is omitted here.

  The thirteenth embodiment is characterized in that the heat exchange area by the cooling water for the second cylinder 2b and the third cylinder 2c is larger than the heat exchange area by the cooling water for the first cylinder 2a and the fourth cylinder 2d. is there.

  Specifically, the basic configuration of the water jacket 5 is the same as that of the twelfth embodiment. In this water jacket 5, the length of the peripheral portion of the second cylinder 2b and the third cylinder 2c (length in the vertical direction of the cylinder block 2) Y2 is defined as the peripheral portion of the first jacket 2a and the fourth cylinder 2d in the water jacket 5. (Length in the vertical direction of the cylinder block 2) Y1.

  In this case, the coolant flow rate to the peripheral portions of the second cylinder 2b and the third cylinder 2c in the water jacket 5 is larger than the coolant flow rate to the peripheral portions of the first cylinder 2a and the fourth cylinder 2d in the water jacket 5. Therefore, the cooling capacity of the second cylinder 2b and the third cylinder 2c can be improved more than the cooling capacity of the first cylinder 2a and the fourth cylinder 2d. Thereby, the 2nd cylinder 2b and the 3rd cylinder 2c can be made easy to radiate heat.

  According to this configuration, it is possible to match the heat dissipation characteristics of the first cylinder 2a and the fourth cylinder 2d with reference to the heat dissipation characteristics of the first cylinder 2a and the fourth cylinder 2d. It is possible to make the compression end temperatures uniform. Therefore, since variation in the self-ignition timing of the air-fuel mixture in each of the combustion chambers 9A to 9D can be reduced, cycle efficiency and thermal efficiency can be improved, and knocking and misfire can be avoided and NOx generation can be reduced.

  Hereinafter, application examples of Embodiment 13 will be described.

  Although not shown, contrary to the above, the length Y1 of the peripheral portion of the first cylinder 2a and the fourth cylinder 2d in the water jacket 5 is set as the peripheral portion of the second cylinder 2b and the third cylinder 2c in the water jacket 5. You may set shorter than length Y2.

  In this case, the coolant flow rate to the peripheral portions of the first cylinder 2a and the fourth cylinder 2d in the water jacket 5 is less than the coolant flow rate to the peripheral portions of the second cylinder 2b and the third cylinder 2c in the water jacket 5. Therefore, the cooling capacity of the first cylinder 2a and the fourth cylinder 2d can be made lower than the cooling capacity of the second cylinder 2b and the third cylinder 2c. This makes it difficult to dissipate heat from the first cylinder 2a and the fourth cylinder 2d. Therefore, it is possible to match the heat radiation characteristics of the first cylinder 2a and the fourth cylinder 2d with reference to the heat radiation characteristics of the second cylinder 2b and the third cylinder 2c, so that the same effect as described above can be obtained.

<Embodiment 14>
With reference to FIG. 31, Embodiment 14 of the multi-cylinder type premixed compression self-ignition engine 1 according to the present invention will be described. Note that the basic configuration of the premixed compression self-ignition engine 1 is the same as that of the first embodiment, and the description thereof is omitted here.

  In the fourteenth embodiment, in addition to the configuration of the simultaneous injection method in which an air-fuel mixture in which air and fuel are mixed in advance is supplied to the intake pipes 15a to 15d, gas injectors 46A to 46D are supplied to all the intake pipes 15a to 15d. Is characterized in that the amount of fuel supplied to the combustion chambers 9A to 9D can be individually controlled.

  Specifically, the air-fuel mixture mixed by the mixer 23 is supplied to all the intake pipes 15a to 15d through the intake surge tank 15, but the amount of fuel supplied to the first intake pipe 15a and the fourth intake pipe 15d. Is controlled by the controller 10 so that the fuel supply amount is set larger than the amount of fuel supplied to the second intake pipe 15b and the third intake pipe 15c. For example, the amount of fuel supplied to the second intake pipe 15b and the third intake pipe 15c may be zero.

  In this case, the fuel concentration in the mixture supplied to the first combustion chamber 9A and the fourth combustion chamber 9D is higher than the fuel concentration in the mixture supplied to the second combustion chamber 9B and the third combustion chamber 9C. Therefore, the residual gas temperature in the first combustion chamber 9A and the fourth combustion chamber 9D becomes higher than the residual gas temperature in the second combustion chamber 9B and the third combustion chamber 9C, and the first combustion chamber in the next cycle. The ignition timing in 9A and the 4th combustion chamber 9D can be advanced.

  That is, it is possible to make the compression end temperatures uniform for each of the combustion chambers 9A to 9D by offsetting the temperature difference for each cylinder with the difference in residual gas concentration. Therefore, since variation in the self-ignition timing of the air-fuel mixture in each of the combustion chambers 9A to 9D can be reduced, cycle efficiency and thermal efficiency can be improved, and knocking and misfire can be avoided and NOx generation can be reduced.

  Hereinafter, application examples of Embodiment 14 will be described.

  Contrary to the above, the amount of fuel supplied to the second intake pipe 15b and the third intake pipe 15c may be set smaller than the amount of fuel supplied to the first intake pipe 15a and the fourth intake pipe 15d. Good. In this case, the fuel concentration in the mixture supplied to the second combustion chamber 9B and the third combustion chamber 9C becomes thinner than the fuel concentration in the mixture supplied to the first combustion chamber 9A and the fourth combustion chamber 9D. Therefore, the residual gas temperature in the second combustion chamber 9B and the third combustion chamber 9C is lower than the residual gas temperature in the first combustion chamber 9A and the fourth combustion chamber 9D, and the second combustion chamber in the next cycle. The ignition timing in 9B and the third combustion chamber 9C can be delayed. That is, it is possible to make the compression end temperatures uniform for each of the combustion chambers 9A to 9D by offsetting the temperature difference for each cylinder with the difference in residual gas concentration. Therefore, the same effect as described above can be obtained.

  Further, by individually controlling the amount of fuel supplied to the combustion chambers 9A to 9D by the gas injectors 46A to 46D, the fuel concentration of the air-fuel mixture for each of the combustion chambers 9A to 9D can be adjusted to be different from each other. it can.

<Embodiment 15>
With reference to FIG. 32, a fifteenth embodiment of the multi-cylinder premixed compression self-ignition engine 1 according to the present invention will be described. Note that the basic configuration of the premixed compression self-ignition engine 1 is the same as that of the first embodiment, and the description thereof is omitted here.

  In the fifteenth embodiment, in addition to the configuration of the simultaneous injection method in which an air-fuel mixture in which air and fuel are mixed in advance is supplied to each of the intake pipes 15a to 15d, the first intake pipe 15a and the fourth intake pipe of the intake surge tank 15 It is characterized in that the gas injectors 46A and 46D are provided only in the intake pipe 15d.

  Specifically, the air-fuel mixture mixed by the mixer 23 is supplied to all the intake pipes 15a to 15d through the intake surge tank 15, but the gas injector 46A is supplied only to the first intake pipe 15a and the fourth intake pipe 15d. , 46D is controlled by the controller 10 to supply fuel. As a result, the fuel concentration in the mixture supplied to the first combustion chamber 9A and the fourth combustion chamber 9D becomes higher than the fuel concentration in the mixture supplied to the second combustion chamber 9B and the third combustion chamber 9C. .

  Therefore, the residual gas temperature in the first combustion chamber 9A and the fourth combustion chamber 9D is higher than the residual gas temperature in the second combustion chamber 9B and the third combustion chamber 9C, and the first combustion chamber in the next cycle. The ignition timing in 9A and the 4th combustion chamber 9D can be advanced. That is, it is possible to make the compression end temperatures uniform for each of the combustion chambers 9A to 9D by offsetting the temperature difference for each cylinder with the difference in the residual gas temperature. Therefore, since variation in the self-ignition timing of the air-fuel mixture in each of the combustion chambers 9A to 9D can be reduced, cycle efficiency and thermal efficiency can be improved, and knocking and misfire can be avoided and NOx generation can be reduced.

<Embodiment 16>
Referring to FIG. 33, a sixteenth embodiment of the multi-cylinder premixed compression self-ignition engine 1 according to the present invention will be described. Note that the basic configuration of the premixed compression self-ignition engine 1 is the same as that of the first embodiment, and the description thereof is omitted here.

  In the sixteenth embodiment, by providing a recess 48 at the top of the second piston 6B and the third piston 6C, the compression volumes of the second combustion chamber 9B and the third combustion chamber 9C are reduced to the first combustion chamber 9A and the fourth combustion. It is characterized in that it is larger than the compression volume of the chamber 9D.

  According to this configuration, the compression ratio in the second combustion chamber 9B and the third combustion chamber 9C can be lowered than the compression ratio in the first combustion chamber 9A and the fourth combustion chamber 9D.

  Here, if the temperature in all the combustion chambers 9A to 9D is constant, the self-ignition timing of the air-fuel mixture in the second combustion chamber 9B and the third combustion chamber 9C is the first combustion chamber 9A and the fourth combustion chamber. This is later than the self-ignition timing of the air-fuel mixture in the combustion chamber 9D. However, in the in-line 4-cylinder type, the temperature in the second combustion chamber 9B and the third combustion chamber 9C is higher than the temperature in the first combustion chamber 9A and the fourth combustion chamber 9D. By reducing the compression ratio of the combustion chamber 9B and the third combustion chamber 9C to be lower than the compression ratio of the first combustion chamber 9A and the fourth combustion chamber 9D, the compression end temperature in the second combustion chamber 9B and the third combustion chamber 9C and 1 It is possible to make the compression end temperatures in the number combustion chamber 9A and the number four combustion chamber 9D substantially the same.

  That is, it is possible to make the compression end temperatures uniform for each of the combustion chambers 9A to 9D by offsetting the temperature difference for each cylinder with the difference in compression ratio. Therefore, since variation in the self-ignition timing of the air-fuel mixture in each of the combustion chambers 9A to 9D can be reduced, cycle efficiency and thermal efficiency can be improved, and knocking and misfire can be avoided and NOx generation can be reduced.

  Hereinafter, application examples of Embodiment 16 will be described.

  Although not shown, contrary to the above, in the first piston 6A and the fourth piston 6D, a convex portion is provided at the top, or the length from the connecting portion to the top of the connecting rod 8A, 8D is increased. By doing so, the compression volumes of the first combustion chamber 9A and the fourth combustion chamber 9D may be made smaller than the compression volumes of the second combustion chamber 9B and the third combustion chamber 9C. In this case, the compression ratio in the first combustion chamber 9A and the fourth combustion chamber 9D can be higher than the compression ratio in the second combustion chamber 9B and the third combustion chamber 9C.

  In this case, if the temperatures in all the combustion chambers 9A to 9D are constant, the self-ignition timing of the air-fuel mixture in the first combustion chamber 9A and the fourth combustion chamber 9D is the second combustion chamber 9B and the third combustion chamber 9D. This is ahead of the self-ignition timing of the air-fuel mixture in the combustion chamber 9C.

  However, in the in-line 4-cylinder type, the temperature in the first combustion chamber 9A and the fourth combustion chamber 9D is lower than the temperature in the second combustion chamber 9B and the third combustion chamber 9C. If the compression ratio of the combustion chamber 9A and the fourth combustion chamber 9D is increased from the compression ratio of the second combustion chamber 9B and the third combustion chamber 9C, the compression end temperature and the second combustion in the first combustion chamber 9A and the fourth combustion chamber 9D. The compression end temperatures in the chamber 9B and the third combustion chamber 9C can be made substantially the same. Thus, the temperature difference for each cylinder can be offset by the difference in compression ratio for each combustion chamber. Therefore, the same effect as described above can be obtained.

<Embodiment 17>
Referring to FIG. 34, a seventeenth embodiment of the multi-cylinder premixed compression self-ignition engine 1 according to the present invention will be described. Note that the basic configuration of the premixed compression self-ignition engine 1 is the same as that of the first embodiment, and the description thereof is omitted here.

  In the seventeenth embodiment, the projection amount Z2 of the second ignition plug 27B into the second combustion chamber 9B and the projection amount Z3 of the third ignition plug 27C into the third combustion chamber 9C are entered into the first combustion chamber 9A. The compression volume of the second combustion chamber 9B and the third combustion chamber 9C is made shallower than the projection amount Z1 of the first ignition plug 27A and the projection amount Z4 of the fourth ignition plug 27D into the fourth combustion chamber 9D. It is characterized in that it is larger than the compression volume of the first combustion chamber 9A and the fourth combustion chamber 9D.

  According to this configuration, the compression ratio in the second combustion chamber 9B and the third combustion chamber 9C can be lowered than the compression ratio in the first combustion chamber 9A and the fourth combustion chamber 9D. In this case, if the temperatures in all the combustion chambers 9A to 9D are constant, the self-ignition timing of the air-fuel mixture in the second combustion chamber 9B and the third combustion chamber 9C is the first combustion chamber 9A and the fourth combustion chamber. This is later than the self-ignition timing of the air-fuel mixture in the combustion chamber 9D. However, in the in-line 4-cylinder type, the temperature in the second combustion chamber 9B and the third combustion chamber 9C is higher than the temperature in the first combustion chamber 9A and the fourth combustion chamber 9D. By reducing the compression ratio of the combustion chamber 9B and the third combustion chamber 9C to be lower than the compression ratio of the first combustion chamber 9A and the fourth combustion chamber 9D, the compression end temperature in the second combustion chamber 9B and the third combustion chamber 9C and 1 It becomes possible to make the compression end temperatures in the number combustion chamber 9A and the number four combustion chamber 9D substantially equal.

  That is, it is possible to make the compression end temperatures uniform for each of the combustion chambers 9A to 9D by offsetting the temperature difference for each cylinder with the difference in compression ratio. Therefore, since variation in the self-ignition timing of the air-fuel mixture in each of the combustion chambers 9A to 9D can be reduced, cycle efficiency and thermal efficiency can be improved, and knocking and misfire can be avoided and NOx generation can be reduced.

  Hereinafter, application examples of Embodiment 17 will be described.

  Although not shown, contrary to the above, the amount of protrusion of the first spark plug 27A into the number one combustion chamber 9A and the amount of protrusion of the number four spark plug 27D into the number four combustion chamber 9D are determined as the second combustion. The first cylinder 2a and the fourth cylinder, which are relatively easy to dissipate heat, are made deeper than the amount of protrusion of the second ignition plug 27B into the chamber 9B and the amount of protrusion of the third ignition plug 27C into the third combustion chamber 9C. The compression volumes of the first combustion chamber 9A and the fourth combustion chamber 9D corresponding to the cylinder 2d are set to the second combustion chamber 9B and the third combustion chamber 9C corresponding to the second cylinder 2b and the third cylinder 2c, which are relatively difficult to dissipate heat. It may be smaller than the compression volume. In this case, the compression ratio in the first combustion chamber 9A and the fourth combustion chamber 9D can be higher than the compression ratio in the second combustion chamber 9B and the third combustion chamber 9C.

  In this case, if the temperatures in all the combustion chambers 9A to 9D are constant, the self-ignition timing of the air-fuel mixture in the first combustion chamber 9A and the fourth combustion chamber 9D is the second combustion chamber 9B and the third combustion chamber 9D. This is ahead of the self-ignition timing of the air-fuel mixture in the combustion chamber 9C.

  However, in the in-line 4-cylinder type, the temperature in the first combustion chamber 9A and the fourth combustion chamber 9D is lower than the temperature in the second combustion chamber 9B and the third combustion chamber 9C. By increasing the compression ratio of the combustion chamber 9A and the fourth combustion chamber 9D from the compression ratio of the second combustion chamber 9B and the third combustion chamber 9C, the compression end temperature in the first combustion chamber 9A and the fourth combustion chamber 9D and the second It is possible to match the compression end temperatures in the combustion chamber 9B and the third combustion chamber 9C. That is, it is possible to make the compression end temperatures uniform for each of the combustion chambers 9A to 9D by offsetting the temperature difference for each cylinder with the difference in compression ratio. Therefore, the same effect as described above can be obtained.

<Embodiment 18>
With reference to FIG. 35, an eighteenth embodiment of the multi-cylinder premixed compression self-ignition engine 1 according to the present invention will be described. Note that the basic configuration of the premixed compression self-ignition engine 1 is the same as that of the first embodiment, and the description thereof is omitted here.

  In the eighteenth embodiment, the length S2 of the 2nd connecting rod 8B and the length S3 of the 3rd connecting rod 8C are made shorter than the length S1 of the 1st connecting rod 8A and the length S4 of the 4th connecting rod 8D. Thus, the compression volumes of the second combustion chamber 9B and the third combustion chamber 9C are larger than the compression volumes of the first combustion chamber 9A and the fourth combustion chamber 9D.

  According to this configuration, the compression ratio in the second combustion chamber 9B and the third combustion chamber 9C can be lowered than the compression ratio in the first combustion chamber 9A and the fourth combustion chamber 9D. In this case, if the temperatures in all the combustion chambers 9A to 9D are constant, the self-ignition timing of the air-fuel mixture in the second combustion chamber 9B and the third combustion chamber 9C is the first combustion chamber 9A and the fourth combustion chamber. This is later than the self-ignition timing of the air-fuel mixture in the combustion chamber 9D. However, in the in-line 4-cylinder type, the temperature in the second combustion chamber 9B and the third combustion chamber 9C is higher than the temperature in the first combustion chamber 9A and the fourth combustion chamber 9D. By reducing the compression ratio of the combustion chamber 9B and the third combustion chamber 9C to be lower than the compression ratio of the first combustion chamber 9A and the fourth combustion chamber 9D, the compression end temperature in the second combustion chamber 9B and the third combustion chamber 9C and 1 It is possible to match the compression end temperatures in the number combustion chamber 9A and the number four combustion chamber 9D. That is, it is possible to make the compression end temperatures uniform for each of the combustion chambers 9A to 9D by offsetting the temperature difference for each cylinder with the difference in compression ratio. Therefore, since variation in the self-ignition timing of the air-fuel mixture in each of the combustion chambers 9A to 9D can be reduced, cycle efficiency and thermal efficiency can be improved, and knocking and misfire can be avoided and NOx generation can be reduced.

  Hereinafter, application examples of the eighteenth embodiment will be described.

  Although not shown in the figure, the first combustion rod 8A and the fourth connecting rod 8D are made longer than the lengths of the second connecting rod 8B and the third connecting rod 8C by conversely with the above. The compression volumes of the chamber 9A and the fourth combustion chamber 9D may be smaller than the compression volumes of the second combustion chamber 9B and the third combustion chamber 9C. In this case, the compression ratio in the first combustion chamber 9A and the fourth combustion chamber 9D can be higher than the compression ratio in the second combustion chamber 9B and the third combustion chamber 9C.

  In this case, if the temperatures in all the combustion chambers 9A to 9D are constant, the self-ignition timing of the air-fuel mixture in the first combustion chamber 9A and the fourth combustion chamber 9D is the second combustion chamber 9B and the third combustion chamber 9D. This is ahead of the self-ignition timing of the air-fuel mixture in the combustion chamber 9C.

  However, in the in-line 4-cylinder type, the temperature in the first combustion chamber 9A and the fourth combustion chamber 9D is lower than the temperature in the second combustion chamber 9B and the third combustion chamber 9C. By increasing the compression ratio of the combustion chamber 9A and the fourth combustion chamber 9D from the compression ratio of the second combustion chamber 9B and the third combustion chamber 9C, the compression end temperature in the first combustion chamber 9A and the fourth combustion chamber 9D and the second It is possible to match the compression end temperatures in the combustion chamber 9B and the third combustion chamber 9C. That is, it is possible to make the compression end temperatures uniform for each of the combustion chambers 9A to 9D by offsetting the temperature difference for each cylinder with the difference in compression ratio. Therefore, the same effect as described above can be obtained.

<Embodiment 19>
A nineteenth embodiment of the multi-cylinder premixed compression self-ignition engine 1 according to the present invention will be described with reference to FIG. Note that the basic configuration of the premixed compression self-ignition engine 1 is the same as that of the first embodiment, and the description thereof is omitted here.

  In this nineteenth embodiment, the second intake valve 17B arranged in the second cylinder 2b and the third intake valve 17C arranged in the third cylinder 2c are closed earlier than the basic closing timing, and this early closing amount is set. It is characterized by intentionally increasing the number.

  The early closing means that the timing for closing the intake valve is set before the piston reaches the bottom dead center.

  According to this configuration, the effective compression ratio of the second combustion chamber 9B and the third combustion chamber 9C can be relatively lowered than the effective compression ratio of the first combustion chamber 9A and the fourth combustion chamber 9D.

  In this case, if the temperatures in all the combustion chambers 9A to 9D are constant, the self-ignition timing of the air-fuel mixture in the second combustion chamber 9B and the third combustion chamber 9C is the first combustion chamber 9A and the fourth combustion chamber. This is later than the self-ignition timing of the air-fuel mixture in the combustion chamber 9D.

  However, in the in-line 4-cylinder type, the temperature in the second combustion chamber 9B and the third combustion chamber 9C is higher than the temperature in the first combustion chamber 9A and the fourth combustion chamber 9D. By reducing the effective compression ratio of the combustion chamber 9B and the third combustion chamber 9C below the effective compression ratio of the first combustion chamber 9A and the fourth combustion chamber 9D, the compression end temperatures in the second combustion chamber 9B and the third combustion chamber 9C And the compression end temperatures in the first combustion chamber 9A and the fourth combustion chamber 9D can be matched.

  That is, it is possible to make the compression end temperatures uniform for each of the combustion chambers 9A to 9D by offsetting the temperature difference for each cylinder with the difference in effective compression ratio. Therefore, since variation in the self-ignition timing of the air-fuel mixture in each of the combustion chambers 9A to 9D can be reduced, cycle efficiency and thermal efficiency can be improved, and knocking and misfire can be avoided and NOx generation can be reduced.

  Hereinafter, application examples of the nineteenth embodiment will be described.

  On the contrary, as shown in FIG. 37, the amount of early closing of the first intake valve 17A disposed in the first cylinder 2a and the fourth intake valve 17D disposed in the fourth cylinder 2d is reduced. The effective compression ratio of the first combustion chamber 9A and the fourth combustion chamber 9D can be made higher than the effective compression ratio of the second combustion chamber 9B and the third combustion chamber 9C.

  In this case, if the temperatures in all the combustion chambers 9A to 9D are constant, the self-ignition timing of the air-fuel mixture in the first combustion chamber 9A and the fourth combustion chamber 9D is the second combustion chamber 9B and the third combustion chamber 9D. This is ahead of the self-ignition timing of the air-fuel mixture in the combustion chamber 9C.

  However, in the in-line 4-cylinder type, the temperature in the first combustion chamber 9A and the fourth combustion chamber 9D is lower than the temperature in the second combustion chamber 9B and the third combustion chamber 9C. By increasing the effective compression ratio of the combustion chamber 9A and the fourth combustion chamber 9D from the effective compression ratio of the second combustion chamber 9B and the third combustion chamber 9C, the compression end temperature in the first combustion chamber 9A and the fourth combustion chamber 9D It is possible to match the compression end temperatures in the second combustion chamber 9B and the third combustion chamber 9C. That is, it is possible to make the compression end temperatures uniform for each of the combustion chambers 9A to 9D by offsetting the temperature difference for each cylinder with the difference in effective compression ratio. Therefore, the same effect as described above can be obtained.

<Embodiment 20>
With reference to FIG. 38, Embodiment 20 of the multicylinder premixed compression self-ignition engine 1 according to the present invention will be described. Note that the basic configuration of the premixed compression self-ignition engine 1 is the same as that of the first embodiment, and the description thereof is omitted here.

  In the twentieth embodiment, the slow closing amount of the second intake valve 17B disposed in the second cylinder 2b and the third intake valve 17C disposed in the third cylinder 2c is set as the first intake disposed in the first cylinder 2a. The valve 17A and the fourth intake valve 17D arranged in the fourth cylinder 2d are closed later than the basic closing timing, and this delay closing amount is intentionally increased.

  The term “slow closing” means that the timing for closing the intake valve is set after the piston reaches bottom dead center.

  In this case, the effective compression ratio of the second combustion chamber 9B and the third combustion chamber 9C can be lowered than the effective compression ratio of the first combustion chamber 9A and the fourth combustion chamber 9D.

  In this case, if the temperatures in all the combustion chambers 9A to 9D are constant, the self-ignition timing of the air-fuel mixture in the second combustion chamber 9B and the third combustion chamber 9C is the first combustion chamber 9A and the fourth combustion chamber. This is later than the self-ignition timing of the air-fuel mixture in the combustion chamber 9D.

  However, in the in-line 4-cylinder type, the temperature in the second combustion chamber 9B and the third combustion chamber 9C is higher than the temperature in the first combustion chamber 9A and the fourth combustion chamber 9D. By reducing the effective compression ratio of the combustion chamber 9B and the third combustion chamber 9C below the effective compression ratio of the first combustion chamber 9A and the fourth combustion chamber 9D, the compression end temperatures in the second combustion chamber 9B and the third combustion chamber 9C And the compression end temperatures in the first combustion chamber 9A and the fourth combustion chamber 9D can be matched.

  That is, it is possible to make the compression end temperatures uniform for each of the combustion chambers 9A to 9D by offsetting the temperature difference for each cylinder with the difference in effective compression ratio. Therefore, since variation in the self-ignition timing of the air-fuel mixture in each of the combustion chambers 9A to 9D can be reduced, cycle efficiency and thermal efficiency can be improved, and knocking and misfire can be avoided and NOx generation can be reduced.

  Hereinafter, application examples of Embodiment 20 will be described.

  Contrary to the above, as shown in FIG. 39, the amount of late closing of the first intake valve 17A disposed in the first cylinder 2a and the fourth intake valve 17D disposed in the fourth cylinder 2d is set to be small. Accordingly, the effective compression ratio of the first combustion chamber 9A and the fourth combustion chamber 9D may be set higher than the effective compression ratio of the second combustion chamber 9B and the third combustion chamber 9C.

  In this case, if the temperatures in all the combustion chambers 9A to 9D are constant, the self-ignition timing of the air-fuel mixture in the first combustion chamber 9A and the fourth combustion chamber 9D is the second combustion chamber 9B and the third combustion chamber 9D. This is ahead of the self-ignition timing of the air-fuel mixture in the combustion chamber 9C.

  However, in the in-line 4-cylinder type, the temperature in the first combustion chamber 9A and the fourth combustion chamber 9D is lower than the temperature in the second combustion chamber 9B and the third combustion chamber 9C. By increasing the effective compression ratio of the combustion chamber 9A and the fourth combustion chamber 9D from the effective compression ratio of the second combustion chamber 9B and the third combustion chamber 9C, the compression end temperature in the first combustion chamber 9A and the fourth combustion chamber 9D It is possible to match the compression end temperatures in the second combustion chamber 9B and the third combustion chamber 9C. That is, it is possible to make the compression end temperatures uniform for each of the combustion chambers 9A to 9D by offsetting the temperature difference for each cylinder with the difference in effective compression ratio. Therefore, the same effect as described above can be obtained.

1 Engine 2 Cylinder block 2a 1st cylinder 2b 2nd cylinder 2c 3rd cylinder 2d 4th cylinder 6A 1st piston 6B 2nd piston 6C 3rd piston 6D 4th piston 9A 1st combustion chamber 9B 2nd combustion chamber 9C 3rd Combustion chamber 9D No. 4 combustion chamber 10 Controller 15 Intake surge tank 15a No. 1 intake pipe 15b No. 2 intake pipe 15c No. 3 intake pipe 15d No. 4 intake pipe 19A to 19D Intake temperature sensor 21 Air filter 22 Throttle 23 Mixer 24 Heater 25 Fuel Supply path 26 Gas injector

Claims (7)

An engine having a plurality of cylinders and supplying an air-fuel mixture in which fuel and air are mixed in advance to the respective combustion chambers of the plurality of cylinders, and combusting the air-fuel mixture by compression auto-ignition in the respective combustion chambers In
At least the top part of the piston of the cylinder that is relatively difficult to dissipate heat among the cylinders is formed of a material having high thermal conductivity so that the compression end temperatures of the combustion chambers of the cylinders are made uniform. A multi-cylinder premixed compression self-ignition engine. An engine having a plurality of cylinders and supplying an air-fuel mixture in which fuel and air are mixed in advance to the respective combustion chambers of the plurality of cylinders, and combusting the air-fuel mixture by compression auto-ignition in the respective combustion chambers In
At least the top part of the piston of the cylinder that is relatively easy to dissipate heat among the cylinders is formed of a material having low thermal conductivity so that the compression end temperatures of the combustion chambers of the cylinders are made uniform. A multi-cylinder premixed compression self-ignition engine. An engine having a plurality of cylinders and supplying an air-fuel mixture in which fuel and air are mixed in advance to the respective combustion chambers of the plurality of cylinders, and combusting the air-fuel mixture by compression auto-ignition in the respective combustion chambers In
At least the tops of the pistons of all the cylinders are formed of materials having relatively different thermal conductivities according to the heat radiation characteristics of each cylinder, and the compression end temperatures of the respective combustion chambers of the respective cylinders are made uniform. A multi-cylinder premixed compression self-ignition engine characterized by An engine having a plurality of cylinders and supplying an air-fuel mixture in which fuel and air are mixed in advance to the respective combustion chambers of the plurality of cylinders, and combusting the air-fuel mixture by compression auto-ignition in the respective combustion chambers In
A heat insulating portion that reduces or blocks heat conduction from the piston to the cylinder is provided on the piston of the cylinder that is relatively easy to dissipate heat among the cylinders, so that the compression end temperatures of the combustion chambers of the cylinders are made uniform. A multi-cylinder premixed compression self-ignition engine characterized by   5. The multi-cylinder premixed compression self-ignition engine according to claim 4, wherein the heat insulating portion is a cavity provided in a thick portion of a piston. An engine having a plurality of cylinders and supplying an air-fuel mixture in which fuel and air are mixed in advance to the respective combustion chambers of the plurality of cylinders, and combusting the air-fuel mixture by compression auto-ignition in the respective combustion chambers In
A multi-cylinder characterized in that an oil jet means for injecting oil to a piston of a cylinder that is relatively difficult to dissipate heat among the cylinders is provided so that the compression end temperatures of the combustion chambers of the cylinders are made uniform. Type premixed compression self-ignition engine. An engine having a plurality of cylinders and supplying an air-fuel mixture in which fuel and air are mixed in advance to the respective combustion chambers of the plurality of cylinders, and combusting the air-fuel mixture by compression auto-ignition in the respective combustion chambers In
Each piston of all cylinders has oil jet means for injecting oil, and each oil jet means individually controls the oil injection amount for each piston in accordance with the heat radiation characteristics for each cylinder. A multi-cylinder premixed compression self-ignition engine characterized by having a uniform compression end temperature for each combustion chamber of a cylinder.

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