JP2021011864A - engine - Google Patents

Abstract

To provide an engine having a crankshaft which is suppressed in the enlargement of a member and a deviation of weight balance.SOLUTION: An engine comprises: a crank journal which is rotatably supported to a cylinder block around a shaft via a crankshaft bearing; a crank pin connected with a connecting rod which is connected to a piston; a crank arm for connecting the crank journal and the crank pin; and flywheel attachment parts attached to both ends of the crank journal in an axial direction. The engine also comprises a first flywheel fixed to the flywheel attachment part at one end in an axial direction, and transmitting rotation to a cam, and a second flywheel fixed to the flywheel attachment part at the other end in the axial direction, and transmitting rotation for traveling.SELECTED DRAWING: Figure 1

Description

The present invention relates to an engine including a crankshaft.

In an engine equipped with a crankshaft, the reciprocating motion of the piston is converted into a rotational force by connecting a connecting rod connected to the piston to the crankshaft.

The crankshaft includes a crank journal corresponding to a rotating shaft, a crank pin to which a connecting rod is connected, and a crank arm to connect the crank journal and the crank pin. Further, the crank arm is provided with a balance weight in order to reduce the inertial force generated by the movement of the piston and the connecting rod. In some cases, the crank arm and the balance weight are integrated to form a crank web. Both ends of the crank journal in the axial direction are rotatably supported around the axis by crankshaft bearings provided near the lower ends of the cylinder block of the engine.

On the other hand, a chain or belt is wound around one end of the crankshaft in the axial direction to drive a cam that opens and closes an intake / exhaust valve, or to drive auxiliary equipment such as an alternator or an air conditioner compressor. The sprockets and pulleys that are turned are connected.

In an engine equipped with this crankshaft, a disk-shaped member called a flywheel is attached to the other end of the crankshaft in the axial direction. A starter gear connected to the rotation shaft of the starter motor is connected to the outer peripheral gear formed on the peripheral edge of the flywheel, and the rotation of the starter motor is input to the crankshaft when the engine is started.

Further, a transmission such as a clutch or a transmission is connected to the other end side of the crankshaft in the axial direction on the outer side of the flywheel in the axial direction. The rotation of the crankshaft is output via the transmission and transmitted to the drive wheels as a driving force for traveling.

Patent Documents 1, 2 and 3 describe a flywheel mounting structure at the other end of the crankshaft in the axial direction, and a mounting structure such as a clutch for the flywheel. Further, Patent Document 4 describes a structure for mounting a pulley at one end in the axial direction of a crankshaft.

In addition, Patent Document 5 describes a structure in which transmissions are connected to the front side and the rear side of the longitudinal engine, and driving force for traveling is output from both front and rear sides of the engine.

Japanese Unexamined Patent Publication No. 6-174014 Jikkenhei 2-90447 Gazette Japanese Patent Laid-Open No. 6-185576 Japanese Unexamined Patent Publication No. 2016-56730 Japanese Unexamined Patent Publication No. 2004-75008

In the engine provided with the crankshaft described in Patent Documents 1 to 4, since the chain or belt is driven via the sprocket or pulley, a large force acts on the shaft end of the crankshaft due to the tension fluctuation of the chain or belt. Will be done. Therefore, the crankshaft is required to have strength and rigidity that can withstand a large bending stress, moment, vibration, etc., and there is a problem that the crankshaft becomes large.

Further, the assembly portion of the sprocket or pulley for driving the cam is located at one end in the axial direction of the crankshaft so as to protrude greatly outward from the crankshaft bearing. For this reason, it is also a cause of increasing the total length of the crankshaft. If the assembled portion of the sprocket or pulley for driving the cam protrudes greatly outward from the crankshaft bearing, there is also a problem that the load applied to the crankshaft bearing also increases.

Further, the crankshaft is in a state in which a heavy flywheel is fixed to the other end side in the axial direction, and such a heavy member is not fixed to the one end side in the axial direction. For this reason, it is difficult to balance the weight of the crankshaft in the axial direction, and such a bias in the weight balance affects the vibration of the entire engine and causes deterioration of work efficiency during assembly work.

In the engine described in Patent Document 5, driving force for traveling is output from both front and rear sides of the engine. However, Patent Document 5 does not describe the internal structure of the engine at all, and the structure of the crankshaft is also unknown. Therefore, the technique of Patent Document 5 cannot solve the above-mentioned problems of increasing the size of the crankshaft and imbalance of the weight balance.

Therefore, an object of the present invention is to provide an engine provided with a crankshaft that suppresses an increase in size of members and an imbalance in weight balance.

In order to solve the above problems, the present invention includes a cylinder formed in a cylinder block, a piston housed in the cylinder so as to be able to move forward and backward, and a combustion chamber formed above the piston in the cylinder. The crankshaft includes an intake / exhaust valve that opens and closes an intake / exhaust passage leading to the combustion chamber, a cam that operates the intake / exhaust valve, and a crankshaft that converts the forward / backward movement of the piston into a rotary movement. A crank journal rotatably supported around the axis via a crankshaft bearing to the cylinder block, a crank pin to which the piston is connected via a connecting rod, a crank arm connecting the crank journal and the crank pin, and the above. A first flywheel provided with flywheel mounting portions provided at both ends in the axial direction of the crank journal, and fixed to the flywheel mounting portion at one end in the axial direction to transmit rotation to the cam, and the other end in the axial direction. An engine including a second flywheel fixed to the flywheel mounting portion and transmitting rotation to the crankshaft was adopted.

Here, it is possible to adopt a configuration in which the rotation of the first flywheel is transmitted to the accessories included in the engine.

Further, the cam includes an intake system cam that operates the intake valve and an exhaust system cam that operates the exhaust valve, and has an intake cam side gear connected to the camshaft of the intake system cam and a camshaft of the exhaust system cam. It is possible to adopt a configuration including an exhaust cam side gear connected to the above and an intermediate gear interposed between the intake cam side gear and the exhaust cam side gear to transmit the rotation of the first flywheel to the cam.

In each of these aspects, the crankshaft can be made up of point-symmetrical members with the axial center thereof interposed therebetween.

Further, in each of these aspects, the rotation transmission to the cam is performed via the rotation transmission unit for the cam, and the rotation transmission unit for the cam is along the outer periphery of the first flywheel or the second flywheel. It operates a configuration including a flywheel side gear that meshes with the formed outer peripheral gear, a cam side gear connected to the cam, and an intermediate gear that transmits the rotation of the flywheel side gear to the cam side gear. Can be done.

INDUSTRIAL APPLICABILITY The present invention can be an engine provided with a crankshaft that suppresses an increase in size of members and an imbalance in weight balance.

Longitudinal section of an engine showing an embodiment of the present invention Right side view of FIG. Top view of the vehicle equipped with the engine of the present invention

Embodiments of the present invention will be described with reference to the drawings. This embodiment is an engine 1 capable of outputting driving force from both sides of the crankshaft 10 in the axial direction, and a vehicle C equipped with the engine 1.

As shown in FIG. 1, the engine 1 includes a cylinder 5 formed in a cylinder block 2 and a piston 4 housed in the cylinder 5 so as to be able to move forward and backward, and a combustion chamber is above the piston 4 in the cylinder 5. 3 is formed. An intake / exhaust passage (intake passage and exhaust passage) is connected to the combustion chamber 3, and an intake / exhaust valve 8 (intake valve and exhaust valve) is provided at each opening of the intake / exhaust passage to the combustion chamber 3. ing. The intake / exhaust valve 8 moves up and down at regular intervals by the rotational operation of a shaft-shaped cam 7 (hereinafter referred to as a camshaft 7) housed in the cylinder head 6 above the cylinder block 2, and the intake / exhaust passage is raised and lowered by the rotation operation. The opening and closing of the opening to the combustion chamber 3 is repeated.

The engine 1 includes a crankshaft 10 at the lower part of the cylinder block 2 that converts the forward / backward movement of the piston 4 in the cylinder 5 into a rotational movement. Below the crankshaft 10, the cylinder block 2 is closed by an oil pan 16.

The crankshaft 10 includes a crank journal 11 rotatably supported around the axis via a crankshaft bearing 14 on a cylinder block 2, a crank pin 12 to which a piston 4 is connected via a connecting rod 9, and a crank journal 11. It includes a crank arm 13 that connects the crank pin 12. The crank journal 11 is divided into a plurality of pieces along the axial direction of the crankshaft 10, and connects the crank arms 13 to each other across adjacent cylinders (intermediate journal portion indicated by reference numeral 11'in the figure). (See), the axial end thereof extends outward in the axial direction from the crank arm 13 and protrudes to the outside of the cylinder block 2.

In the crankshaft 10, the crank journal 11 at the end in the axial direction is rotatably supported by the cylinder block 2 via the crankshaft bearing 14. Further, the intermediate journal portion 11'is also rotatably supported by the cylinder block 2 via the crankshaft bearing 14. The type of the crankshaft bearing 14 is a vertically divided slide bearing (metal bearing).

The crankshaft 10 is provided with flywheel mounting portions 15 at both ends in the axial direction of the crank journal 11. The flywheel mounting portion 15 is a flange-shaped member having a diameter larger than the outer diameter of the crank journal 11. The flywheel mounting portion 15 is fixed to the crank journals 11 at both ends of the crankshaft 10 on the axially outer side of the crankshaft bearing 14, that is, on the outer side of the cylinder block 2.

Flywheels 20 and 30, respectively, are attached to both ends of the crankshaft 10 in the axial direction. In FIG. 1, the flywheel 20 fixed to the flywheel mounting portion 15 on one end side in the axial direction shown on the right side in the drawing is hereinafter referred to as the first flywheel 20. The first flywheel 20 transmits rotation to the camshaft 7. Further, the flywheel 30 fixed to the flywheel mounting portion 15 on the other end side in the axial direction shown on the left side in the drawing is hereinafter referred to as a second flywheel 30. The second flywheel 30 performs rotation transmission for transmitting a driving force for traveling. Both the first flywheel 20 and the second flywheel 30 are fixed to the end face of the flywheel mounting portion 15 by fixing bolts (not shown).

The rotation of the first flywheel 20 is transmitted to the camshaft 7 via the cam rotation transmission unit A. As shown in FIG. 2, the cam rotation transmission unit A of this embodiment includes a flywheel side gear 21 that meshes with an outer peripheral gear (ring gear) 20a formed along the outer periphery of the first flywheel 20, and a camshaft 7. A cam-side gear 24 connected to the end of the flywheel and an intermediate gear 23 for transmitting the rotation of the flywheel-side gear 21 to the cam-side gear 24 are provided. The intermediate gear 23 of this embodiment is composed of a worm. As shown in FIG. 1, the outer peripheral gear 20a is formed on the side surface of the first flywheel 20 on the engine 1 side, and the flywheel side gear 21 is an external gear (spur gear or hashes) that meshes with the outer peripheral gear 20a. It is composed of flywheels, etc.). The rotation of the flywheel side gear 21 is transmitted to the intermediate gear 23 through the transmission shaft 22. The rotation of the intermediate gear 23 is connected to each camshaft 7 constituting the intake system cam 7a and the exhaust system cam 7b, transmitted to the cam side gear 24 located on the engine 1 side of the first flywheel 20, and is transmitted to the cam side gear. Together with 24, each camshaft 7 rotates in opposite directions around the axis. The cam-side gear 24 is composed of external gears (spur gears, helical gears, etc.) that mesh with an intermediate gear 23 made of a worm. The worm of the intermediate gear 23 is sandwiched between the cam-side gears 24 on the intake side and the exhaust side and meshes with each other.

The rotation of the second flywheel 30 is transmitted to the wheel W included in the vehicle C on which the engine 1 is mounted via the traveling rotation transmission unit B. As shown in FIGS. 1 and 3, the traveling rotation transmission unit B of this embodiment provides a driving force transmission means 40 including a transmission such as a clutch or a transmission connected to the outer side in the axial direction of the second flywheel 30. I have. The rotation of the crankshaft 10 is output at a predetermined rotation speed via the driving force transmission means 40, and is a drive wheel via the propeller shaft 41, the differential 42, and the drive shaft 43 constituting the traveling rotation transmission unit B. It is transmitted to the wheel W.

On the other hand, the rotation of the first flywheel 20 is also transmitted to the auxiliary machinery 60 included in the engine 1. Examples of the auxiliary equipment 60 include auxiliary equipment such as an alternator and a compressor of an air conditioner. Although the figure shows only one auxiliary machine 60, a plurality of auxiliary machines 60 may be provided. An auxiliary gear 62 is connected to the input shaft 61 of the auxiliary machinery 60. The auxiliary gear 62 is composed of external gears (spur gears, helical gears, etc.) and meshes with the outer peripheral gear 20a of the first flywheel 20. Therefore, when the first flywheel 20 rotates, the rotation is input to the auxiliary equipment 60.

Further, the driving force of the starter motor 50 is input to the second flywheel 30. A starter gear 52 is connected to the rotating shaft 51 of the starter motor 50. The starter gear 52 is composed of an external gear (spur gear, helical gear, etc.) and meshes with the outer peripheral gear (ring gear) 30a of the second flywheel 30. Therefore, when the engine is started, the rotation of the starter motor 50 is input to the crankshaft 10.

As shown in FIG. 3, the outer peripheral gear 30a may be formed along the outer edge of the second flywheel 30 toward the outer diameter side, and the starter gear 52 may be meshed with the outer diameter gear 30a facing the outer diameter side. Good. This also applies to the first flywheel 20, the outer peripheral gear 20a is formed along the outer edge of the first flywheel 20 toward the outer diameter side, and the flywheel side gear 21 and the auxiliary gear 62 are formed therein. It may be meshed with the outer peripheral gear 20a facing the outer diameter side.

The crankshaft 10 has the above configuration, and in particular, the crankshaft 10 of this embodiment is composed of point-symmetrical members with the center in the axial direction thereof interposed therebetween.

In the present invention, the flywheels 20 and 30 included in the engine 1 are arranged as the first flywheel 20 and the second flywheel 30 in two places, so that the members of the flywheels 20 and 30 can be made smaller in each place. There is an advantage that the height of the engine 1 can be reduced. Further, since this engine 1 does not have a sprocket or pulley assembly for driving a cam as in the conventional case, the total length of the crankshaft 10 can be shortened, the engine 1 can be made compact in the lateral direction, and the crankshaft can be reduced. There is also an advantage that the material cost that composes the engine can be reduced.

Further, in the present invention, since there is no sprocket or pulley for driving the cam as in the prior art, tension of the timing chain, timing belt, etc. of the cam drive system and associated bending stress act on the crankshaft 10. Will not work. Therefore, the load acting on the crankshaft bearing 14, particularly the impact load, is reduced, and the effect of extending the life of the engine 1 can be expected.

Further, according to the present invention, the flywheels 20 and 30 are arranged on both sides of the crankshaft 10 in the axial direction, with respect to the parallel direction of the cylinders 5 of the engine 1, that is, in the front-rear direction of the engine 1 in this embodiment. Since it can be used even if the axial direction of the crankshaft 10 is reversed 180 degrees, the degree of freedom of work in engine assembly and processing is increased, and the weight balance of the members is good, so work safety and work when carrying the members It can also contribute to the improvement of efficiency.

Further, the weight balance of the crankshaft 10 and the weight balance of the engine 1 using the crankshaft 10 are good, so that the vibration of the entire engine 1 can be reduced. In particular, since the crankshaft 10 is point-symmetric with respect to the center in the axial direction, the vibration in the axial direction of the crankshaft 10 can be canceled out more efficiently. The oil pump (not shown) for supplying oil to each part of the engine 1 is usually driven by the rotation of the crankshaft 10, but in the present invention, the oil pump is electric or electric. , The oil pump may be driven by the same mechanism as the rotation transmission unit A for the cam.

The crankshaft 10 in FIG. 1 is a crankshaft of a 4-cylinder engine for a gasoline vehicle, and is the first crank journal 11, the first crank pin 12, and the second crank journal 11 (intermediate journal portion 11) from the left side. '), No. 2 crank pin 12, No. 3 crank journal 11 (intermediate journal part 11'), No. 3 crank pin 12, No. 4 crank journal 11 (intermediate journal part 11'), No. 4 crank pin It is equipped with the 12th and 5th crank journals 11. Then, each crank journal 11 and the crank pin 12 are joined by a crank arm 13, the crank journals 11 are arranged in parallel on the same axis, and the sliding surfaces of the crank journals 11 are arranged linearly. There is. Further, crank pins 12 are arranged in parallel on the same axis at positions predetermined away from the axis of the crank journal 11. Further, another crank pin 12 group is arranged in parallel on the same axis at a position (180 °) opposite to the crank pin 12 group on one side of the axis of the crank journal 11. As a result, the sliding surface (outer peripheral surface) of the crank pin 12 is located at a predetermined position around the axis of the crank journal 11. Further, a fillet portion is formed between the side surface of the crank arm 13 and the axial end of the crank journal 11, and a fillet portion is also formed between the side surface of the crank arm 13 and the axial end of the crank pin 12.

In this embodiment, since the cam rotation transmission unit A is arranged between the first flywheel 20 and the cylinder block 2 and on the cylinder head 6, the cam rotation transmission unit A is not exposed to the outside. Further, the first flywheel 20 is protected by a cover or the like attached to the end surface of the engine 1.

Regarding the cam rotation transmission unit A, in order to make the rotation speed of the cam shaft 7 = the rotation speed of the crankshaft 10 × 1/2, when an intermediate gear 23 made of a worm is used,
Camshaft rotation speed = intermediate gear rotation speed / worm reduction ratio = (crankshaft rotation speed x flywheel outer gear gear number)
/ (Number of teeth in intermediate gear x worm reduction ratio)
It can be dealt with by. In the case of the cam rotation transmission unit A using such a worm, the rotation of the camshaft 7 is not transmitted in the opposite direction to rotate the worm due to the small backlash characteristic of the worm.

In this embodiment, the rotation of the first flywheel 20 is transmitted to both camshafts 7 constituting the intake system cam 7a and the exhaust system cam 7b. As a modification thereof, for example, the first fly The rotation of the wheel 20 may be transmitted only to the intake system cam 7a, and the rotation of the second flywheel 30 may be transmitted only to the exhaust system cam 7b. Alternatively, conversely, the rotation of the first flywheel 20 may be transmitted only to the exhaust system cam 7b, and the rotation of the second flywheel 30 may be transmitted only to the intake system cam 7a. In this case, the cam rotation transmission unit A is arranged on each of the first flywheel 20 and the second flywheel 30.

Further, in this embodiment, the configuration of the present invention has been described by taking as an example a 4-cylinder engine having four cylinders in series as the engine 1, but the present invention is not limited to this embodiment. The present invention can also be applied to other types of engines 1 having different numbers and arrangements of cylinders. Further, in this embodiment, the configuration of the present invention has been described by taking the longitudinal engine vehicle C having the rear wheels as the driving wheels as an example, but the transverse engine vehicle having the front wheels as the driving wheels, and the front and rear wheels as the driving wheels. The present invention can also be applied to a four-wheel drive vehicle. Further, the present invention can be applied not only to an in-line engine but also to a V-type engine by arranging a cam rotation transmission unit A having the above configuration for each bank.

1 Engine 2 Cylinder block 3 Combustion chamber 4 Piston 5 Cylinder 7 Cam (camshaft)
7a Intake system cam 7b Exhaust system cam 8 Intake / exhaust valve 9 Connecting rod 10 Crankshaft 11 Crankjourna 12 Crankpin 13 Crankarm 14 Crankshaft bearing 15 Flywheel mounting part 20 First flywheel 20a, 30a Outer gear 21 Flywheel side Gear 22 Transmission shaft 23 Intermediate gear (worm)
24 Cam side gear 30 2nd flywheel A Rotation transmission unit for cam B Rotation transmission unit for traveling

Claims (5)

A cylinder formed in a cylinder block, a piston housed in the cylinder so as to be able to move forward and backward, a combustion chamber formed above the piston in the cylinder, and a suction chamber that opens and closes an intake / exhaust passage leading to the combustion chamber. It includes an exhaust valve, a cam that operates the intake / exhaust valve, and a crankshaft that converts the forward / backward movement of the piston into a rotational movement.
The crankshaft connects a crank journal rotatably supported around the axis via a crankshaft bearing to the cylinder block, a crank pin to which the piston is connected via a connecting rod, and the crank journal and the crank pin. A crank arm and flywheel mounting portions provided at both ends of the crank journal in the axial direction are provided.
A first flywheel that is fixed to the flywheel mounting portion at one end in the axial direction and transmits rotation to the cam.
A second flywheel that is fixed to the flywheel mounting portion at the other end in the axial direction and transmits rotation to the crankshaft.
Engine equipped with. The engine according to claim 1, wherein the rotation of the first flywheel is transmitted to auxiliary machinery included in the engine. The cam includes an intake system cam that operates an intake valve and an exhaust system cam that operates an exhaust valve.
The intake cam side gear connected to the camshaft of the intake system cam and
The exhaust cam side gear connected to the camshaft of the exhaust system cam and
The engine according to claim 1 or 2, further comprising an intermediate gear that is interposed between the intake cam side gear and the exhaust cam side gear and transmits the rotation of the first flywheel to the cam. The engine according to any one of claims 1 to 3, wherein the crankshaft is composed of a member having point symmetry with the center in the axial direction interposed therebetween. The rotation transmission to the cam is performed via the rotation transmission unit for the cam.
The rotation transmission unit for the cam
A flywheel-side gear that meshes with an outer peripheral gear formed along the outer circumference of the first flywheel or the second flywheel.
The cam side gear connected to the cam and
An intermediate gear that transmits the rotation of the flywheel side gear to the cam side gear,
The engine according to any one of claims 1 to 4.

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