Engine

Abstract

To effectively reduce piston striking noise.SOLUTION: An engine includes: a cylinder block having a cylinder formed therein; a piston having a piston body provided within the cylinder and a movable piston skirt rotatably mounted to the piston body; and a hydraulic pressure supply mechanism having a hydraulic device provided in the piston skirt and having a hydraulic pressure reception port formed on an outer peripheral surface of the piston skirt, a hydraulic pressure supply port formed at a position capable of facing the hydraulic pressure reception port on an inner wall surface of the cylinder, an oil supply source and an oil passage provided within the cylinder block and allowing the oil supply source to communicate with the hydraulic pressure supply port. In the hydraulic pressure supply mechanism, hydraulic pressure supplied from the oil supply source is supplied from the hydraulic pressure reception port on the inner wall surface of the cylinder to the hydraulic pressure reception port of the hydraulic device through the oil passage, and the hydraulic device uses the hydraulic pressure to rotate the piston skirt in a direction in which a lower side of the piston skirt comes close to the inner wall surface of the cylinder.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] Conventionally, a piston reciprocates within a cylinder as a result of combustion of an air-fuel mixture in the combustion chamber of an engine, and this reciprocating motion of the piston is converted into rotational motion of a crankshaft via a connecting rod.

[0003] The combustion pressure generated when the air-fuel mixture is burned in the combustion chamber acts on the piston, causing it to collide with the inner wall of the cylinder. At this time, the sound of the piston colliding with the inner wall of the cylinder, known as piston slap noise, is generated. Hereinafter, piston slap noise will be referred to as piston slapping noise.

[0004] To reduce such piston slapping noise, for example, the engine described in Patent Document 1 provides a movable piston skirt on the piston body, and a coil spring is provided between the movable piston skirt and the piston body. As a result, the impact when the movable piston skirt collides with the inner wall surface of the cylinder is buffered by the action of the coil spring, thereby reducing piston slapping noise. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Utility Model Application Publication No. 61-29054 Summary of the Invention [Problem to be solved by the invention]

[0006] However, to effectively reduce piston slapping noise, it is important to maintain an appropriate small clearance between the lower side of the piston skirt and the inner wall surface of the cylinder. Furthermore, the clearance between the inner wall surface of the cylinder and the piston, as well as the behavior of the piston within the cylinder, change depending on the engine's operating conditions. Therefore, simply providing a coil spring does not allow the appropriate small clearance between the lower side of the piston skirt and the inner wall surface of the cylinder to be maintained depending on the engine's operating conditions, making it difficult to effectively reduce piston slapping noise.

[0007] Therefore, an object of the present invention is to provide an engine that can effectively reduce piston smacking noise. [Means for solving the problem]

[0008] In order to solve the above problem, an engine according to one embodiment of the present invention comprises: a cylinder block in which a cylinder is formed; a piston having a piston body provided in the cylinder and a movable piston skirt rotatably attached to the piston body; a hydraulic device provided in the piston skirt and having a hydraulic pressure receiving port formed on an outer peripheral surface of the piston skirt; a hydraulic supply mechanism including a hydraulic supply port formed on an inner wall surface of the cylinder at a position capable of opposing the hydraulic pressure receiving port, an oil supply source, and an oil passage provided in the cylinder block and communicating between the oil supply source and the hydraulic pressure supply port; Equipped with The hydraulic supply mechanism supplies hydraulic pressure from the oil supply source through the oil passage from the hydraulic supply port on the inner wall surface of the cylinder to the hydraulic receiving port of the hydraulic device, and the hydraulic device uses the hydraulic pressure to rotate the piston skirt in a direction in which the lower side of the piston skirt approaches the inner wall surface of the cylinder. [Effects of the Invention]

[0009] According to the present invention, piston slapping noise can be effectively reduced. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram showing a vehicle according to one embodiment of the present invention. [Figure 2] FIG. 2 is a schematic view showing the engine according to the embodiment. [Figure 3] FIG. 3 is a schematic view showing a piston according to the embodiment. [Figure 4] FIG. 4 is a cross-sectional view showing a piston skirt having a hydraulic device according to the same embodiment. [Figure 5] FIG. 5 is a schematic diagram showing a hydraulic pressure supply mechanism according to the embodiment. [Figure 6] FIG. 6 is an enlarged cross-sectional view showing a piston skirt according to the embodiment. [Figure 7] FIG. 7 is a block diagram showing the control device according to the embodiment. [Figure 8] FIG. 8 is a block diagram showing an example of a functional configuration of the control device according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Specific dimensions, materials, numerical values, etc. shown in the embodiments are merely examples for facilitating understanding of the invention and do not limit the present invention unless otherwise specified. In this specification and drawings, elements having substantially the same functions and configurations are designated by the same reference numerals to avoid redundant explanation, and elements not directly related to the present invention are not shown.

[0012] Fig. 1 is a schematic diagram showing a vehicle 100 according to one embodiment of the present invention. As shown in Fig. 1, the vehicle 100 includes an engine 200 and a control device 300. The vehicle 100 according to this embodiment is an engine vehicle using the engine 200 as a drive source. However, the present invention is not limited to this, and the vehicle 100 may also be a hybrid vehicle using the engine 200 and a motor (not shown) as a drive source.

[0013] FIG. 2 is a schematic diagram showing engine 200 according to this embodiment. In FIG. 2, arrow Y indicates the longitudinal direction, which is the forward / rearward traveling direction of vehicle 100, arrow Z indicates the vertical direction of vehicle 100, and arrow X indicates the left / right direction relative to the traveling direction of vehicle 100. As shown in FIG. 2, engine 200 includes a cylinder block 210, a crankcase 220, a cylinder head 230, a head cover 240, a crankshaft 250, and an oil pan 260. Engine 200 according to this embodiment is a horizontally opposed four-cylinder engine in which a pair of cylinder blocks 210, a pair of crankcases 220, a pair of cylinder heads 230, and a pair of head covers 240 are arranged opposite each other with crankshaft 250 sandwiched between them. However, engine 200 is not limited to this, and may be an in-line engine, a V-type engine, or the like.

[0014] A crankcase 220 is formed integrally with the cylinder block 210. However, the cylinder block 210 and the crankcase 220 may be formed as separate bodies and connected to each other. A pair of crankcases 220 facing each other across the crankshaft 250 are connected to each other and form a crank chamber 222 (see FIG. 3) therein. A cylinder head 230 is connected to the side of the cylinder block 210 opposite the crankcase 220. Furthermore, a head cover 240 is connected to the side of the cylinder head 230 opposite the cylinder block 210.

[0015] A plurality of cylinders 212 are formed in the cylinder block 210. A piston 400 is slidably disposed in each of the plurality of cylinders 212, and the pistons 400 are supported by connecting rods 214. A space surrounded by the cylinders 212, the cylinder head 230, and the crown surfaces of the pistons 400 forms a combustion chamber 216.

[0016] The piston 400 is connected to the crankshaft 250 via a connecting rod 214. The crankshaft 250 is supported by the crankcase 220 so as to be able to rotate freely.

[0017] An intake port 232 and an exhaust port 234 are formed in the cylinder head 230. One end of the intake port 232 is connected to an intake flow path (not shown), and the other end of the intake port 232 is connected to the combustion chamber 216. One end of the exhaust port 234 is connected to the combustion chamber 216, and the other end of the exhaust port 234 is connected to an exhaust flow path (not shown). The tip of an intake valve 236 is located between the intake port 232 and the combustion chamber 216. The tip of an exhaust valve 238 is located between the exhaust port 234 and the combustion chamber 216.

[0018] The space enclosed by the cylinder head 230 and the head cover 240 is formed as a cam chamber 242. Within the cam chamber 242, an intake valve cam 244 and an exhaust valve cam 246 are disposed.

[0019] The intake valve cam 244 abuts against the base end of the intake valve 236. As the intake valve cam 244 rotates, the intake valve 236 moves in the axial direction. This opens and closes the communication between the intake port 232 and the combustion chamber 216. When the intake valve 236 is in an open state, air as intake air flowing through the intake flow path is introduced into the combustion chamber 216 via the intake port 232.

[0020] The exhaust valve cam 246 abuts against the base end of the exhaust valve 238. When the exhaust valve cam 246 rotates, the exhaust valve 238 moves in the axial direction, thereby opening and closing the communication between the exhaust port 234 and the combustion chamber 216.

[0021] An injector (not shown) and a spark plug (not shown) are provided in cylinder head 230. The injector injects fuel to supply the fuel into combustion chamber 216. The tip of the spark plug is disposed within combustion chamber 216, and ignites the mixture of fuel and air supplied into combustion chamber 216.

[0022] The fuel-air mixture is ignited by a spark plug at a predetermined timing and burned. The combustion pressure generated when the mixture is burned causes piston 400 to move in a direction away from combustion chamber 216, and this movement away from combustion chamber 216 is converted into rotational motion of crankshaft 250 via connecting rod 214. The rotational motion of crankshaft 250 then moves piston 400 toward the combustion chamber via connecting rod 214, causing piston 400 to perform reciprocating motion. In addition, exhaust gases generated by the combustion of the mixture are discharged into the exhaust passage via exhaust port 234 when exhaust valve 238 is open.

[0023] Oil pan 260 is provided below cylinder block 210 and crankcase 220. Oil pan 260 is, for example, a hollow trapezoidal container. Oil pan 260 is connected to cylinder block 210 and crankcase 220 so that the space inside oil pan 260 communicates with crank chamber 222. Oil pan 260 stores oil 270.

[0024] A strainer 262 for sucking oil into oil pump 264 is provided within oil pan 260. Strainer 262 is formed in a cylindrical shape. At the tip of strainer 262, an inlet port 262a that opens into oil pan 260 is formed. Inlet port 262a is spaced apart from the bottom surface of oil pan 260 and is disposed opposite the bottom surface of oil pan 260. Inlet port 262a is located below the surface of oil 270 stored in oil pan 260.

[0025] An oil pump 264 serving as an oil supply source is connected to the strainer 262. When the oil pump 264 is driven, the strainer 262 draws oil 270 stored in the oil pan 260 through an inlet 262a. Foreign matter is removed from the oil 270 drawn through the inlet 262a by the strainer 262, and the oil 270 is supplied to each part of the engine 200 via the oil pump 264. The oil 270 supplied to each part of the engine 200 lubricates the parts of the engine 200, and then returns to the oil pan 260.

[0026] Fig. 3 is a schematic diagram showing a piston 400 according to this embodiment. As shown in Fig. 3, the piston 400 includes a piston body 410 and a pair of piston skirts 420. The piston body 410 is formed in a substantially cylindrical shape.

[0027] A crown surface 410a facing the combustion chamber 216 is formed on the upper surface of the piston body 410. An insertion hole 410b is formed in the piston body 410, through which a piston pin (not shown) connected to the connecting rod 214 (see FIG. 2) is inserted.

[0028] A first groove 412, a second groove 414, and a third groove 416 are formed on the outer circumferential surface of the piston body 410 between the crown surface 410a and the insertion hole 410b. The first groove 412, the second groove 414, and the third groove 416 are formed in an annular shape. The first groove 412 is formed closer to the crown surface 410a than the second groove 414 and the third groove 416. The second groove 414 is formed between the first groove 412 and the third groove 416. The third groove 416 is formed closer to the insertion hole 410b than the first groove 412 and the second groove 414.

[0029] A first piston ring 412a is fitted in the first groove 412. A second piston ring 414a is fitted in the second groove 414. A third piston ring 416a is fitted in the third groove 416. The outer diameters of the first piston ring 412a, the second piston ring 414a, and the third piston ring 416a are larger than the outer diameter of the crown surface 410a of the piston body 410. The outer peripheral surfaces of the first piston ring 412a, the second piston ring 414a, and the third piston ring 416a are configured to be slidable on the inner wall surface 212a of the cylinder 212.

[0030] The first piston ring 412a is called the top ring, and the second piston ring 414a is called the second ring. The first piston ring 412a and the second piston ring 414a have the function of preventing gas leakage from the combustion chamber 216 toward the crank chamber 222. The third piston ring 416a is called the oil ring, and has the function of scraping off excess oil on the inner wall surface 212a of the cylinder 212 and preventing oil from entering the combustion chamber 216.

[0031] The pair of piston skirts 420 are arranged on both sides of the insertion hole 410b of the piston body 410. In other words, the pair of piston skirts 420 are arranged in a direction perpendicular to the central axis of the insertion hole 410b. The pair of piston skirts 420 are supported by a pair of fulcrums 410c provided on the piston body 410. The pair of fulcrums 410c are provided in the lower part of the third groove 416. The pair of fulcrums 410c are provided symmetrically with respect to the insertion hole 410b. Therefore, the pair of piston skirts 420 supported by the pair of fulcrums 410c are also arranged symmetrically with respect to the insertion hole 410b.

[0032] In this embodiment, the pair of piston skirts 420 are configured to be movable. The movable piston skirts 420 are attached to the piston body 410 so as to be rotatable about a fulcrum 410c.

[0033] When an air-fuel mixture is burned in the combustion chamber, combustion pressure acts on the piston, causing it to collide with the inner wall of the cylinder. At this time, a piston slapping noise is generated, which is the sound of the piston hitting the inner wall of the cylinder.

[0034] To effectively reduce piston slap noise, it is important to maintain an appropriate small clearance between the lower side of the piston skirt and the inner wall surface of the cylinder. However, constantly maintaining a small clearance would result in increased friction in the low-load, low-rpm range where piston slap noise is not a problem. Furthermore, the clearance between the inner wall surface of the cylinder and the piston, as well as the behavior of the piston within the cylinder, change depending on the engine's operating conditions. Therefore, if it is not possible to maintain an appropriate small clearance between the lower side of the piston skirt and the inner wall surface of the cylinder depending on the engine's operating conditions, it will be difficult to effectively reduce piston slap noise.

[0035] Therefore, the piston skirt 420 of this embodiment effectively reduces piston slapping noise by including a hydraulic device 430 that operates by hydraulic pressure supplied from the inner wall surface 212a of the cylinder 212. First, the configuration of the piston skirt 420 having the hydraulic device 430 according to this embodiment will be described in detail below, and then the configuration of the hydraulic pressure supply mechanism 600 that supplies hydraulic pressure from the inner wall surface 212a of the cylinder 212 will be described in detail.

[0036] Fig. 4 is a cross-sectional view showing a piston skirt 420 having hydraulic devices 430 according to this embodiment. In the example shown in Fig. 4, two hydraulic devices 430 are provided for each piston skirt 420, and a total of four hydraulic devices 430 are provided for each pair of piston skirts 420.

[0037] The two hydraulic devices 430 provided on each piston skirt 420 are spaced apart along the central axial direction of the piston pin (not shown). One hydraulic device 430 is provided on one side of the fulcrum 410c, and one hydraulic device 430 is provided on the other side of the fulcrum 410c. However, this is not limiting, and each piston skirt 420 does not necessarily have to be provided with multiple hydraulic devices 430. For example, each piston skirt 420 may be provided with only one hydraulic device 430.

[0038] 4, the hydraulic device 430 includes a hydraulic pressure receiving port 432, a communication hole 434, a hydraulic cylinder 436, a hydraulic piston 438, a rod 440, and a spring 442. The hydraulic pressure receiving port 432 is formed on the outer peripheral surface of the piston skirt 420. The hydraulic pressure receiving port 432 guides hydraulic pressure supplied from the inner wall surface 212a of the cylinder 212 to the communication hole 434. One end of the communication hole 434 is connected to the hydraulic pressure receiving port 432, and the other end of the communication hole 434 is connected to the hydraulic cylinder 436. The communication hole 434 communicates between the hydraulic pressure receiving port 432 and the hydraulic cylinder 436.

[0039] The hydraulic cylinder 436 forms an accommodation space that accommodates a hydraulic piston 438, a portion of the rod 440, and a spring 442. The hydraulic piston 438 divides the accommodation space of the hydraulic cylinder 436 into a hydraulic chamber 436a and a spring accommodation chamber 436b. The hydraulic chamber 436a communicates with the communication hole 434, and oil 270 that has passed through the communication hole 434 is introduced into the hydraulic chamber 436a. The spring accommodation chamber 436b accommodates a portion of the rod 440 and the spring 442. One end of the rod 440 is connected to the hydraulic piston 438, and the other end of the rod 440 is connected to a support portion 410d of the piston body 410. The rod 440 is supported by the support portion 410d.

[0040] The spring 442 is disposed in the spring accommodating chamber 436b and generates a pressing force that presses the hydraulic piston 438 toward the hydraulic chamber 436a.

[0041] 5 is a schematic diagram showing a hydraulic pressure supply mechanism 600 according to this embodiment. As shown in FIG. 5, the cylinder block 210 is provided with the hydraulic pressure supply mechanism 600 for supplying hydraulic pressure from the inner wall surface 212a of the cylinder 212 to the hydraulic device 430 of the piston skirt 420.

[0042] A strainer 262, an oil pump 264, and an oil supply pipe 266 are provided at the bottom of the cylinder block 210. One end of the oil supply pipe 266 is connected to the oil pump 264, and the other end of the oil supply pipe 266 is connected to the cylinder block 210.

[0043] An oil passage 500 is formed in cylinder block 210. An oil supply pipe 266 connects oil pump 264 and oil passage 500. Oil supply pipe 266 guides oil 270 delivered from oil pump 264 to oil passage 500.

[0044] Oil 270 is sucked from suction port 262 a of strainer 262 by oil pump 264 , and foreign matter is removed by strainer 262 before passing through oil supply pipe 266 and being introduced into oil passage 500 in cylinder block 210 .

[0045] Oil passage 500 includes a main gallery 510, a first branched oil passage 520, and a second branched oil passage 530. Main gallery 510 guides oil 270 supplied from oil supply pipe 266 to first branched oil passage 520, second branched oil passage 530, and each lubrication part of engine 200.

[0046] The first branched oil passage 520 is an oil passage branching off from the main gallery 510, and guides the oil 270 supplied from the main gallery 510 to a hydraulic pressure supply port 610 formed in the inner wall surface 212a of the cylinder 212. The hydraulic pressure supply port 610 is in communication with the first branched oil passage 520. The oil 270 that has flowed through the first branched oil passage 520 is supplied to the hydraulic device 430 of the piston skirt 420 via the hydraulic pressure supply port 610.

[0047] A first valve 522 and a second valve 524 are provided in the first branched oil passage 520. The first valve 522 is provided in the first branched oil passage 520 near the main gallery 510. The first valve 522 is provided between the main gallery 510 and the second valve 524. The first valve 522 is an oil control valve that can adjust the oil pressure of the oil 270 flowing through the first branched oil passage 520.

[0048] The second valve 524 is provided in the first branched oil passage 520 near a hydraulic pressure supply port 610 formed in the inner wall surface 212a of the cylinder 212. The second valve 524 is provided downstream of the first valve 522 in the first branched oil passage 520. The second valve 524 is provided between the first valve 522 and the hydraulic pressure supply port 610. The second valve 524 is an electromagnetic valve that can open and close the first branched oil passage 520.

[0049] The second branch oil passage 530 is an oil passage that branches off from the main gallery 510 and guides the oil 270 supplied from the main gallery 510 to an opening 218 a formed in the main journal support portion 218 .

[0050] 2. An opening 218a formed in the main journal support portion 218 communicates with the second branched oil passage 530. The oil 270 that flows through the second branched oil passage 530 is supplied to the main journal of the crankshaft 250 via the opening 218a.

[0051] First branch oil passage 520 is formed at a position different from second branch oil passage 530. Furthermore, first branch oil passage 520 does not communicate with second branch oil passage 530. By forming first branch oil passage 520 and second branch oil passage 530 independently of each other in this manner, the oil pressure in first branch oil passage 520 can be adjusted by first valve 522 without affecting the oil pressure in second branch oil passage 530.

[0052] In this embodiment, the hydraulic pressure supply mechanism 600 includes the strainer 262, the oil pump 264, the oil supply pipe 266, the oil passage 500, the first valve 522, the second valve 524, and a hydraulic pressure supply port 610. The hydraulic pressure supply mechanism 600 according to this embodiment supplies hydraulic pressure from the oil pump 264 to the hydraulic device 430 of the piston skirt 420 via the hydraulic pressure supply port 610 formed in the inner wall surface 212a of the cylinder 212.

[0053] 3, the hydraulic pressure supply port 610 is formed at a position on the inner wall surface 212a of the cylinder 212 that can face the hydraulic pressure receiving port 432 of the piston skirt 420. For example, the position of the hydraulic pressure supply port 610 is a position that faces the hydraulic pressure receiving port 432 formed on the outer peripheral surface of the piston skirt 420 when the piston 400 is at the bottom dead center.

[0054] 5 adjusts the hydraulic pressure supplied from the hydraulic pressure supply port 610 to the hydraulic device 430 in the piston skirt 420. The second valve 524 starts or stops the supply of hydraulic pressure to the hydraulic device 430 by opening or closing the first branch oil passage 520.

[0055] 6 is an enlarged cross-sectional view showing piston skirt 420 according to this embodiment. As shown in FIG. 6, hydraulic pressure receiving port 432 is formed by a curved surface in a bowl shape recessed inward from the outer circumferential surface of piston skirt 420.

[0056] In the direction of the central axis of the cylinder 212, the width of the hydraulic pressure inlet 432 is greater than the width of the hydraulic pressure supply port 610. This makes it possible to absorb variations in the opening and closing timing of the second valve 524 and facilitate the introduction of the oil 270 from the hydraulic pressure supply port 610 to the hydraulic pressure inlet 432. Therefore, the hydraulic pressure inlet 432 can receive the oil 270 supplied from the hydraulic pressure supply port 610 even at a position shifted from the bottom dead center of the piston 400.

[0057] 7 is a block diagram showing a control device 300 according to this embodiment. The control device 300 controls the entire vehicle 100. As shown in FIG. 7, the control device 300 includes an I / F 310, a storage device 320, a system bus 330, one or more processors 340, and one or more memories 350.

[0058] I / F 310 is an interface for exchanging data with an oil temperature sensor 360, a crank angle sensor 370, and a throttle opening sensor 380 provided in vehicle 100. Oil temperature sensor 360 is provided in oil pan 260 shown in FIG. 2. Oil temperature sensor 360 detects the temperature of oil 270 stored in oil pan 260 and transmits a signal indicating the oil temperature to control device 300. Crank angle sensor 370 detects the crank angle of crankshaft 250 of engine 200 and the engine speed and transmits a signal indicating the crank angle and engine speed to control device 300. Throttle opening sensor 380 detects the rotation angle of a shaft of a throttle valve (not shown) of engine 200 and transmits a signal indicating the rotation angle to control device 300.

[0059] The storage device 320 is composed of RAM, flash memory, HDD, etc., and holds various information necessary for the processing of the processor 340 described below. The system bus 330 electrically connects the I / F 310, storage device 320, processor 340, and memory 350, and is a transmission path for transmitting data among them.

[0060] The processor 340 includes, for example, a CPU (Central Processing Unit). The memory 350 includes, for example, a ROM (Read Only Memory) and a RAM (Random Access Memory). The ROM is a storage element that stores programs and calculation parameters used by the CPU. The RAM is a storage element that temporarily stores data such as variables and parameters used in processing executed by the CPU.

[0061] Fig. 8 is a block diagram showing an example of the functional configuration of the control device 300 according to this embodiment. For example, as shown in Fig. 8, the control device 300 includes a valve control unit 300a.

[0062] The processor 340 cooperates with and executes the programs stored in the memory 350 to realize various processes including the processes described below that are performed by the valve control unit 300a.

[0063] Valve control unit 300a controls first valve 522 and second valve 524 based on signals from oil temperature sensor 360, crank angle sensor 370, and throttle opening sensor 380. The processing of valve control unit 300a will be described in detail below.

[0064] First, valve control section 300 a controls first valve 522 based on signals from oil temperature sensor 360 , crank angle sensor 370 , and throttle opening sensor 380 , and controls the oil pressure of oil 270 flowing through first branch oil passage 520 .

[0065] Specifically, the valve control unit 300a acquires a signal indicating the temperature of the oil 270 from an oil temperature sensor 360. The valve control unit 300a also acquires a signal indicating the engine speed, which is the rotation speed of the crankshaft 250, from a crank angle sensor 370. The valve control unit 300a also acquires a signal indicating the rotation angle of the throttle valve shaft from a throttle opening sensor 380.

[0066] Then, the valve control unit 300a calculates the oil temperature, engine speed, and engine load based on the acquired signals. Here, the storage device 320 pre-stores an oil pressure map that shows the relationship between the engine speed, the engine load, and the oil pressure regulated by the first valve 522. Note that the oil pressure map is generated for each oil temperature of the oil 270. Therefore, the storage device 320 stores a plurality of oil pressure maps for each oil temperature. The oil pressure map is set so that the oil pressure regulated by the first valve 522 increases as the oil temperature of the oil 270 decreases. The oil pressure map is also set so that the oil pressure regulated by the first valve 522 increases as the engine speed or engine load increases.

[0067] The valve control unit 300a refers to a hydraulic pressure map stored in the storage device 320 and derives a hydraulic pressure corresponding to the calculated oil temperature, engine speed, and engine load. The valve control unit 300a controls the first valve 522 so that the hydraulic pressure of the oil 270 flowing through the first branch oil passage 520 becomes the derived hydraulic pressure. This allows an appropriate hydraulic pressure to be supplied from the hydraulic pressure supply port 610 on the inner wall surface 212a of the cylinder 212 to the hydraulic device 430 of the piston skirt 420 depending on the operating state of the engine 200.

[0068] The oil 270, whose oil pressure has been adjusted by the first valve 522, is supplied to the oil pressure receiving port 432 of the piston skirt 420 via the oil pressure supply port 610 of the first branch oil passage 520. The oil 270 supplied to the oil pressure receiving port 432 is introduced into the oil pressure chamber 436a via the communication hole 434.

[0069] When the hydraulic pressure in hydraulic chamber 436a becomes greater than the biasing force of spring 442, the volume of hydraulic chamber 436a expands and the volume of spring accommodating chamber 436b contracts. At this time, piston skirt 420 rotates around fulcrum 410c of piston body 410 in a direction approaching inner wall surface 212a of cylinder 212.

[0070] As piston skirt 420 rotates, the clearance between the lower side of piston skirt 420 and inner wall surface 212a of cylinder 212 becomes an appropriate, minute clearance. Because this clearance is extremely small, ranging from a few μm to a dozen μm, the oil pressure supplied to hydraulic chamber 436a is maintained at least for the time it takes for piston 400 to move from bottom dead center to top dead center. Therefore, the clearance between the lower side of piston skirt 420 and inner wall surface 212a of cylinder 212 is maintained at least from bottom dead center to top dead center of piston 400. In other words, the outer shape of piston skirt 420 is maintained at least from bottom dead center to top dead center of piston 400.

[0071] When the piston 400 is near the top dead center, the air-fuel mixture is combusted in the combustion chamber 216, and the crown surface 410a of the piston 400 receives the combustion pressure, which generates a rotational moment around the central axis of the piston pin, that is, a so-called swinging motion.

[0072] However, because the clearance between the lower side of piston skirt 420 and inner wall surface 212a of cylinder 212 is an appropriate minute clearance, even if a swinging motion occurs, it is possible to reduce the collision energy with inner wall surface 212a of cylinder 212. In addition, because the lower side of piston skirt 420 has lower rigidity than the upper side, it is possible to reduce piston slapping noise compared to when the upper side is caused to collide with inner wall surface 212a.

[0073] Furthermore, because an appropriate oil pressure is supplied to hydraulic device 430 based on the oil pressure map as described above, the lower part of piston skirt 420 and inner wall surface 212a of cylinder 212 can be brought into close proximity with an appropriate small clearance regardless of the operating state of engine 200. As a result, piston slapping noise can be effectively reduced regardless of the operating state of the engine.

[0074] Furthermore, the valve control unit 300a calculates the crank angle of the crankshaft 250 based on a signal obtained from the crank angle sensor 370. Then, the valve control unit 300a determines whether or not the piston 400 is at bottom dead center based on the calculated crank angle.

[0075] If it is determined that the piston 400 is at the bottom dead center, the valve control unit 300a controls the second valve 524 to an open state. On the other hand, if it is determined that the piston 400 is not at the bottom dead center, the valve control unit 300a controls the second valve 524 to a closed state.

[0076] As a result, when the hydraulic pressure supply port 610 does not face the hydraulic pressure receiving port 432 of the piston skirt 420, the second valve 524 closes the first branched oil passage 520, thereby preventing the oil 270 from leaking into the cylinder 212. Therefore, when the hydraulic pressure supply port 610 does not face the hydraulic pressure receiving port 432 of the piston skirt 420, the hydraulic pressure in the first branched oil passage 520 decreases, preventing adverse effects on other lubrication systems.

[0077] As described above, the engine 200 of this embodiment is equipped with a movable piston skirt 420 equipped with a hydraulic device 430. The engine 200 of this embodiment also includes a hydraulic pressure supply mechanism 600 that can supply hydraulic pressure to the hydraulic device 430 of the piston skirt 420 from the inner wall surface 212a of the cylinder 212. The hydraulic pressure supply mechanism 600 supplies hydraulic pressure supplied from the oil pump 264 from a hydraulic pressure supply port 610 on the inner wall surface 212a of the cylinder 212 to the hydraulic pressure receiving port 432 of the hydraulic device 430 through the first branch oil passage 520. The hydraulic device 430 uses hydraulic pressure to rotate the piston skirt 420 in a direction in which the lower side of the piston skirt 420 approaches the inner wall surface 212a of the cylinder 212. As a result, the clearance between the lower side of the piston skirt 420 and the inner wall surface 212a of the cylinder 212 is an appropriate, minute clearance, so that even if a swinging motion occurs, the collision energy with the inner wall surface 212a of the cylinder 212 can be reduced. In addition, because the lower side of the piston skirt 420 has lower rigidity than the upper side, piston slapping noise can be reduced compared to when the upper side is caused to collide with the inner wall surface 212a. In addition, because the hydraulic pressure supplied to the hydraulic device 430 is supplied from the inner wall surface 212a of the cylinder 212, the structure of the piston 400 can be simplified compared to when a hydraulic circuit is formed to supply hydraulic pressure to the inside of the piston 400. As a result, piston slapping noise can be effectively reduced with a simple configuration.

[0078] The hydraulic pressure supply mechanism 600 of this embodiment includes a first valve 522 that can adjust the hydraulic pressure supplied from a hydraulic pressure supply port 610 on the inner wall surface 212a of the cylinder 212 to the hydraulic device 430 in the piston skirt 420. This makes it possible to adjust the hydraulic pressure of the oil 270 delivered from the oil pump 264 to an appropriate hydraulic pressure for bringing the lower part of the piston skirt 420 and the inner wall surface 212a of the cylinder 212 close to each other with an appropriate small clearance.

[0079] The engine 200 of this embodiment includes a control device 300 that controls the first valve 522. The control device 300 adjusts the hydraulic pressure supplied to the hydraulic device 430 by controlling the first valve 522 in accordance with the operating state of the engine. This allows the lower part of the piston skirt 420 and the inner wall surface 212a of the cylinder 212 to be brought into close proximity with an appropriate small clearance, regardless of the operating state of the engine 200, and effectively reduces piston slapping noise.

[0080] The hydraulic pressure supply mechanism 600 of the present embodiment includes a second valve 524 that can open and close the first branched oil passage 520. As a result, when the hydraulic pressure supply port 610 does not face the hydraulic pressure receiving port 432 of the piston skirt 420, the second valve 524 closes the first branched oil passage 520, thereby preventing the oil 270 from leaking into the cylinder 212. Therefore, when the hydraulic pressure supply port 610 does not face the hydraulic pressure receiving port 432 of the piston skirt 420, the hydraulic pressure in the first branched oil passage 520 can be prevented from decreasing and adversely affecting other lubrication systems.

[0081] In this embodiment, the position of the hydraulic pressure supply port 610 on the inner wall surface 212a of the cylinder 212 is a position opposite to the hydraulic pressure receiving port 432 formed on the outer peripheral surface of the piston skirt 420 when the piston 400 is located at bottom dead center. This allows the hydraulic pressure supply port 610 to be provided on the inner wall surface 212a of the cylinder 212 on a side that is farther away from the combustion chamber 216 than the sliding ranges in which the first piston ring 412a, the second piston ring 414a, and the third piston ring 416a slide. This makes it possible to prevent oil supplied from the hydraulic pressure supply port 610 from entering the combustion chamber 216.

[0082] While the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to these embodiments. It is clear that those skilled in the art can conceive of various modifications and alterations within the scope of the claims, and it is understood that these modifications and alterations also fall within the technical scope of the present invention.

[0083] In the above embodiment, an example has been described in which storage device 320 stores an oil pressure map for each oil temperature of oil 270 stored in oil pan 260. However, without being limited to this, storage device 320 may store an oil pressure map provided for each water temperature of the coolant circulating inside engine 200. Storage device 320 may also store an oil pressure map provided for each oil temperature and each water temperature.

[0084] In the above embodiment, an example has been described in which the first valve 522 is provided in the first branched oil passage 520. However, the first valve 522 is not an essential component, and the first valve 522 does not necessarily have to be provided in the first branched oil passage 520.

[0085] In the above embodiment, an example has been described in which the valve control unit 300a controls the first valve 522 to adjust the hydraulic pressure in accordance with the operating state of the engine 200. However, the present invention is not limited to this, and the valve control unit 300a does not have to control the first valve 522 in accordance with the operating state of the engine 200. For example, the valve control unit 300a may control the first valve 522 so that the hydraulic pressure is constant regardless of the operating state of the engine 200.

[0086] In the above embodiment, an example has been described in which the second valve 524 is provided in the first branched oil passage 520. However, the second valve 524 is not an essential component, and the second valve 524 does not necessarily have to be provided in the first branched oil passage 520.

[0087] In the above embodiment, an example has been described in which the position of the hydraulic pressure supply port 610 on the inner wall surface 212a of the cylinder 212 is opposite the hydraulic pressure receiving port 432 on the piston skirt 420 when the piston 400 is at the bottom dead center. However, the present invention is not limited to this, and the position of the hydraulic pressure supply port 610 on the inner wall surface 212a of the cylinder 212 may be opposite the hydraulic pressure receiving port 432 on the piston skirt 420 when the piston 400 is at the top dead center. In this case, the valve control unit 300a controls the second valve 524 to an open state when it determines that the piston 400 is at the top dead center, and controls the second valve 524 to a closed state when it determines that the piston 400 is not at the top dead center. [Explanation of symbols]

[0088] 100 vehicles 200 Engine 210 cylinder block 212 cylinders 212a Inner wall 262 Strainer 264 Oil Pump 300 control device 300a Valve control section 360 Oil temperature sensor 370 Crank angle sensor 380 Throttle Opening Sensor 400 piston 420 Piston Skirt 430 Hydraulic System 432 Hydraulic inlet 434 Communication hole 436 Hydraulic Cylinder 438 Hydraulic Piston 440 rod 442 Spring 500 Oil road 510 Main Gallery 520 First Branch Oil Line 522 First Valve 524 Second Valve 530 Second Branch Oil Channel 600 Hydraulic supply mechanism 610 Hydraulic supply port

Claims

1. a cylinder block in which a cylinder is formed; a piston having a piston body provided in the cylinder and a movable piston skirt rotatably attached to the piston body; a hydraulic device provided in the piston skirt and having a hydraulic pressure receiving port formed on an outer peripheral surface of the piston skirt; a hydraulic supply mechanism including a hydraulic supply port formed on an inner wall surface of the cylinder at a position capable of opposing the hydraulic pressure receiving port, an oil supply source, and an oil passage provided in the cylinder block and communicating between the oil supply source and the hydraulic pressure supply port; Equipped with The hydraulic pressure supply mechanism supplies hydraulic pressure supplied from the oil supply source through the oil passage from the hydraulic pressure supply port on the inner wall surface of the cylinder to the hydraulic pressure receiving port of the hydraulic device, and the hydraulic device uses the hydraulic pressure to rotate the piston skirt in a direction in which a lower side of the piston skirt approaches the inner wall surface of the cylinder. engine.

2. The hydraulic pressure supply mechanism includes: a first valve capable of adjusting the hydraulic pressure supplied from the hydraulic pressure supply port on the inner wall surface of the cylinder to the hydraulic device within the piston skirt; 10. The engine of claim 1.

3. a control device that adjusts the hydraulic pressure supplied to the hydraulic device by controlling the first valve in accordance with an operating state of the engine; 3. The engine of claim 2.

4. The hydraulic pressure supply mechanism includes: a second valve capable of opening and closing the oil passage; An engine according to any one of claims 1 to 3.

5. the hydraulic pressure supply port on the inner wall surface of the cylinder is located at a position opposite to the hydraulic pressure receiving port of the piston skirt when the piston is located at the bottom dead center; An engine according to any one of claims 1 to 3.

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