JP2000220465A - Gear train of engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the size and weight by providing a crank gear on a crankshaft, each balancer gear on a pair of balancer shafts, a first idler gear meshed with the crank gear and one balancer gear, and a second idler gear meshed with the first idler gear and the other balancer gear. SOLUTION: A serial 4-cycle diesel engine comprises two balancer shafts 2, 3 on the right and left sides and a gear train 10 for transmitting the rotation of a crankshaft 1 to each balancer shaft 2, 3 on the front part of an engine, Each balancer shaft 2, 3 is rotated in the mutually reverse directions at a speed 2 times the crankshaft 1 through the gear grain 10 to suppress the rotation secondary vibration of the engine. The gear train 10 comprises a crank gear 13 on the crankshaft 1, balancer bears 14, 15 on each balancer shaft 2, 3, a first idler gear 11 meshed with each gear 13, 15, and a second idler gear meshed with each gear 11, 14 to reduce the number of idler gears.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in an engine gear train.

[0002]

2. Description of the Related Art Some automotive engines and the like rotate a pair of balancer shafts having an unbalanced mass in opposite directions to each other in synchronization with the engine rotation to cancel the inertial force of a piston or the like (for example, JP-A-9-2101
No. 35 gazette).

A structure in which a balancer shaft is driven via a gear train composed of a plurality of gears has the advantage of higher rotational accuracy and reliability than a structure using a timing belt or a chain.

[0004] The gear train shown in FIGS.
Each of them has a conventional structure, and each is constituted by six gears.

First, the gear train shown in FIG. 4 will be described. A crank gear 33 connected to the front end of the crankshaft, balancer gears 34 and 35 connected to the front end of each balancer shaft, the crank gear 33 and the balancer gear 34 First idler gear 31 interposed between
And a second idler gear 32 and a third idle gear 36 interposed between the crank gear 33 and the balancer gear 35. The rotation of the crank gear 33 is transmitted to the left balancer gear 34 via the first idler gear 31 and transmitted to the right balancer gear 35 via the second idler gear 32 and the third idler gear 36. As described above, since each balancer shaft differs in the number of idler gears to be relayed by one, the rotation directions thereof are opposite to each other.

In FIG. 4, reference numeral 37 denotes a pump gear connected to a front end of a rotary shaft of a fuel injection pump (not shown).
The pump gear 37 meshes with the third idler gear 36 and transmits the rotation of the crankshaft to the rotation shaft of the fuel injection pump.

Next, the gear train shown in FIG. 5 will be described. A crank gear 43 connected to the front end of the crankshaft, balancer gears 44 and 45 connected to the front end of each balancer shaft, the crank gear 43 and the balancer gear 45 and a second idler gear 42 interposed between the crank gear 43 and the balancer gear 44.
And a third idle gear 46. The rotation of the crank gear 43 is transmitted to the right balancer gear 45 via the first idler gear 41 and transmitted to the left balancer gear 44 via the second idler gear 42 and the third idler gear 46. Also in this case, since the balancer shafts differ in the number of idler gears to be relayed by one, their rotation directions are opposite to each other.

In FIG. 5, reference numeral 47 denotes a pump gear connected to a front end of a rotary shaft of a fuel injection pump (not shown).
The pump gear 47 meshes with the third idler gear 46 and transmits the rotation of the crankshaft to the rotation shaft of the fuel injection pump.

Next, the gear train shown in FIG. 6 will be described. A crank gear 53 connected to the front end of the crankshaft, balancer gears 54 and 55 connected to the front end of each balancer shaft, the crank gear 53 and the balancer gear A first idler gear (oil pump driving gear) 51 interposed between the first idler gear 55 and a second idler gear 52 interposed between the crank gear 53 and the balancer gear 54
And third idle gear (fuel injection pump drive gear) 5
And 6. The rotation of the crank gear 53 is transmitted to the right balancer gear 55 via the first idler gear 51 and transmitted to the left balancer gear 54 via the second idler gear 52 and the third idler gear 56. Also in this case, since the balancer shafts differ in the number of idler gears to be relayed by one, their rotation directions are reversed. The third idle gear 57 is connected to a front end of a rotary shaft of a fuel injection pump (not shown), and also functions as a pump gear for driving the fuel injection pump.

[0010]

However, such a conventional engine gear train has six gears for reversing the two balancer shafts with each other. However, the weight of the apparatus has increased and the size of the apparatus has been increased.

In the gear train shown in FIG. 4, since the rotation of the crank gear 33 is transmitted to the pump gear 36 via the second idler gear 32 and the third idle gear 36, gear backlash and the like. Therefore, there is a problem that the error of the fuel injection timing due to the above increases.

The present invention has been made in view of the above problems, and has as its object to reduce the size and weight of a gear train of an engine that drives a balancer shaft.

[0013]

The first invention is applied to a gear train of an engine that transmits the rotation of a crankshaft to a pair of balancer shafts and rotates the balancer shafts in opposite directions.

A crank gear connected to the crankshaft, a pair of balancer gears connected to each balancer shaft, a first idler gear meshing with the crank gear and one balancer gear, a first idler gear and the other balancer gear And a second idler gear meshing with the second idler gear.

According to a second aspect of the present invention, in the first aspect, a pump gear is provided which is coupled to a rotary shaft of the fuel injection pump, and the pump gear meshes with the first idler gear.

According to a third aspect, in the second aspect, a camshaft for driving at least one of an intake valve and an exhaust valve to open and close, a cam sprocket connected to the camshaft, and a rotary shaft of the fuel injection pump are provided. Pump sprocket, and a chain that is wound around the pump sprocket and the cam sprocket.

[0017]

According to the first aspect of the invention, the rotation of the crank gear is transmitted to one balancer gear via the first idler gear, and is transmitted to the other balancer gear via the first idler gear and the second idler gear. Conveyed to. Since each balancer shaft differs in the number of idler gears to be relayed by one, the rotation directions thereof are opposite to each other.

The first idler gear has a function of inverting and transmitting the rotation of the crank gear to one of the balancer gears,
The function of transmitting the rotation of the crank gear to the other balancer gear in the same rotation direction via the second idler gear is achieved. For this reason, the gear train can be composed of five gears, and the number of gears can be reduced by one as compared with the conventional device. By reducing the number of gears in the gear train in this way, it is possible to reduce mechanical noise, reduce friction loss, reduce engine weight, and reduce product cost.

In the second invention, the rotation of the crankshaft is transmitted to the fuel injection pump via the crank gear, the first idler gear and the pump gear, and pressurizes high-pressure fuel to the injector of each cylinder at a predetermined timing. Thus, by minimizing the number of idler gears that transmit rotation to the fuel injection pump, errors in fuel injection timing due to gear backlash and the like can be reduced. As a result, while maintaining the performance of the engine, the vibration of the engine can be suppressed.

In the third aspect, the rotation of the crankshaft is transmitted to the camshaft via the crank gear, the first idler gear, the pump gear, the pump sprocket, the chain, and the cam sprocket to open and close the intake and exhaust valves. As a result, the length of the chain can be reduced, the power loss of the engine can be reduced, and the weight of the engine can be reduced.

[0021]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

As shown in FIG. 3, the in-line four-cylinder diesel engine includes two balancer shafts 2 and 3 on the left and right sides of a cylinder block 4 in parallel with the crankshaft 1.
Each balancer shaft 2, 3 is rotatably supported by a cylinder block 4 via a bearing (not shown).

As shown in FIG. 2, a gear train 10 for transmitting the rotation of the crankshaft 1 to the balancer shafts 2 and 3 is provided at the front of the engine. During operation of the engine, the balancer shafts 2 and 3 rotate in opposite directions at twice the speed of the crankshaft 1 via the gear train 10, and the centrifugal force acting on the respective unbalance masses 2a and 3a causes the pistons and connecting rods to rotate. Counteracts inertial force and suppresses secondary rotational vibration of the engine.

As shown in FIG. 1, the gear train 10
A crank gear 13 connected to the front end of the crankshaft 1, balancer gears 14 and 15 connected to the front ends of the balancer shafts 2 and 3, a first idler gear 11 meshing with the crank gear 13 and the balancer gear 15,
The first idler gear 11 and the second idler gear 12 meshing with the balancer gear 14 are provided. That is, the first idler gear 11 is interposed between the crank gear 13 and the balancer gear 15, and the second idler gear 12 is interposed between the first idler gear 11 and the balancer gear 14.

In this embodiment, in FIG. 1, the balancer shaft 2 rotates counterclockwise and the balancer shaft 3 rotates clockwise. However, the balancer shaft 2 is rotated clockwise and the balancer shaft is rotated. 3 may be rotated counterclockwise.

The number of teeth of each of the balancer gears 14 and 15 is set to １ ／ of the number of teeth of the crank gear 13. Thereby, each balancer shaft 2, 3 rotates at twice the speed of the crankshaft 1.

1 and 2, reference numeral 16 denotes a pump gear connected to the front end of a rotary shaft of a fuel injection pump (not shown). The pump gear 16 meshes with the first idler gear 11, and transmits the rotation of the crankshaft 1 to the rotation shaft of the fuel injection pump. The number of teeth of the pump gear 16 is the crank gear 1
3 is set to twice the number of teeth. Thus, the rotation axis of the fuel injection pump rotates at half the speed of the crankshaft 1, and pumps high-pressure fuel to the injector of each cylinder at a predetermined timing.

In FIG. 2, reference numeral 17 denotes a cam sprocket. A cam shaft for opening and closing the intake / exhaust valves is provided on a cylinder head (not shown).
Is coupled to the front end of the camshaft. A pump sprocket 18 together with a pump gear 16 is provided on a rotary shaft of the fuel injection pump.
Are coupled, a chain 19 is wound around the pump sprocket 18 and the cam sprocket 17, and the rotation of the crankshaft 1 is transmitted to the camshaft. In FIG. 2, reference numeral 21 denotes a chain tensioner which is pressed against the chain 19 to apply a predetermined tension.

The operation is described below, with the above configuration.

The rotation of the crank gear 13 is transmitted to the right balancer gear 15 via the first idler gear 11 and the first idler gear 11 and the second idler gear 1 are transmitted.
2 is relayed to the balancer gear 14 on the left. Since the balancer shafts 2 and 3 differ in the number of idler gears to be relayed by one, the rotation directions of the balancer shafts 2 and 3 are opposite to each other. In this way, the balancer shafts 2 and 3 rotate in reverse in synchronization with the rotation of the crankshaft 1, so that
The centrifugal force acting on each of the unbalance masses 2a and 3a cancels the inertial force of the piston, the connecting rod, and the like, thereby suppressing the rotational secondary vibration of the engine.

The first idler gear 11 has a function of inverting and transmitting the rotation of the crank gear 13 to the right balancer gear 15 and a function of transmitting the rotation of the crank gear 13 to the left balancer gear 14 via the second idler gear 12. Fulfill the function of transmitting. For this reason, the gear train 10 can be composed of five gears, and the number of gears can be reduced by one as compared with the conventional device. By reducing the number of gears in the gear train 10 in this manner, reduction of mechanical noise, reduction of friction loss,
The engine weight is reduced and the cost of the product is reduced.

A support shaft rotatably supporting the first idler gear 11 via a bearing (not shown) is fastened to the cylinder block 4 via a bolt. Since the bolt for fastening the support shaft is located directly above the bearing of the crankshaft 1, if the diameter of the first idler gear 11 is small, a cap for fastening the bearing (bearing cap) of the crankshaft 1 to the cylinder block 4. There is a possibility that the rigidity of the cylinder block 4 is reduced due to interference with bolts or the like. In response to this, the outer diameter of the first idler gear 11 is set large,
The bolt for fastening the support shaft is sufficiently separated from the cap bolt. By reducing the number of idler gears having a large diameter in this manner, the effect of reducing the mechanical noise, the effect of reducing the friction loss, and the effect of reducing the engine weight are increased.

In the fuel injection pump, the rotation of the crankshaft 1 is transmitted via the crank gear 13, the first idler gear 11, and the pump gear 16, and pumps high-pressure fuel to the injector of each cylinder at a predetermined timing. By minimizing the number of idler gears that transmit rotation to the fuel injection pump in this way, errors in fuel injection timing due to gear backlash and the like can be reduced, and engine vibration can be suppressed.

The rotation of the crankshaft 1 is controlled by the crankshaft 13, the first idler gear 11, the pump gear 16 and the pump sprocket 18.
Is transmitted through the chain 19 and the cam sprocket 17 to open and close the intake / exhaust valve, thereby shortening the length of the chain 19, minimizing the power loss of the engine, and reducing the engine weight.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a gear train showing an embodiment of the present invention.

FIG. 2 is a front view of the gear train.

FIG. 3 is a schematic front view of a balancer shaft and the like.

FIG. 4 is a configuration diagram of a gear train showing a conventional example.

FIG. 5 is a configuration diagram of a gear train showing a conventional example.

FIG. 6 is a configuration diagram of a gear train showing a conventional example.

[Explanation of symbols]

 Reference Signs List 1 crankshaft 2 balancer shaft 3 balancer shaft 4 cylinder block 10 gear train 11 first idler gear 12 second idler gear 13 crank gear 14 balancer gear 15 balancer gear 16 pump gear 17 cam sprocket 18 pump sprocket 19 chain

Claims (3)

[Claims] An engine gear train for transmitting rotation of a crankshaft to a pair of balancer shafts and rotating the balancer shafts in opposite directions, wherein: a crank gear coupled to the crankshaft; and the balancer shafts. And a second idler gear meshing with the crank gear and one balancer gear, and a second idler gear meshing with the first idler gear and the other balancer gear. . 2. The engine gear train according to claim 1, further comprising a pump gear coupled to a rotation shaft of a fuel injection pump, wherein the pump gear meshes with the first idler gear. 3. A camshaft for driving at least one of an intake valve and an exhaust valve to open and close; a cam sprocket coupled to the camshaft; a pump sprocket coupled to a rotary shaft of the fuel injection pump; and the pump sprocket. 3. The engine gear train according to claim 2, further comprising: and a chain wound around the cam sprocket.