JP2002235819A - Tensioner for timing belt for outboard engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a hydraulic damper from being brought into a poor operation state when a tensioner for an automobile engine is applied to an outboard engine. SOLUTION: A support member 40 is provided to rotatably support a roller 38 spliced to a timing belt 31 and be oscillatorily supported to an engine body. A first compression coil spring 44 is provided to energize the support member 40 to the timing belt 31 side. The support member 40 is provided with a hydraulic reducer 41 of which a hydraulic cylinder 48 making contact with one end of a piston rod 50 consists. The hydraulic damper 41 is disposed such that the piston rod 50 and a pointer 50 point the rear side in the running direction of the timing belt 31 from a spliced part between the roller 38 and the timing belt 31.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a timing belt tensioner for an outboard motor having a hydraulic damper.

[0002]

2. Description of the Related Art Conventionally, as a tensioner which abuts on a timing belt of an outboard motor to apply tension thereto, for example, as disclosed in JP-A-7-77254, a roller which abuts on a timing belt is used. Some are supported swingably on the engine body. In the tensioner disclosed in this publication, the roller is rotatably supported by a bracket, and the bracket is swingably mounted on the engine body.

[0003] By loosening a bolt for fixing the bracket to the engine body and changing the swing angle, the amount by which the roller presses the timing belt (the tension of the timing belt) can be adjusted. However, the position of the roller could not be changed during the operation of the engine. For this reason, the tension of the timing belt cannot always be set to an optimum value. This is because the distance between the crankshaft and the camshaft becomes longer due to thermal expansion after the engine is started.

Such a problem can be solved to some extent by using a tensioner for an automobile engine having an automatic tension adjusting function. As a tensioner of this kind, a roller attached to a timing belt is rotatably supported by a support member, and the support member is swingable to an engine body via a swing shaft eccentric with respect to the axis of the roller. Some have been supported.

In this tensioner for an automobile engine, the supporting member is urged toward the timing belt by a compression coil spring so that the tension of the timing belt is substantially constant even when the distance between the crankshaft and the camshaft changes. Can be kept. If a structure in which the support member and the roller are urged by a compression coil spring is employed, the roller and the support member may vibrate due to disturbance such as rapid rotation fluctuation. Therefore, the tensioner is provided with a hydraulic damper. This hydraulic damper is constituted by a hydraulic cylinder in which one end of a piston rod is brought into contact with the support member. When the piston is pressed by the support member together with the piston rod, resistance is generated by an internal throttle and vibration occurs. Is attenuated.

[0006]

However, if the tensioner for an automobile engine constructed as described above is diverted to an outboard motor, the hydraulic damper may not operate. This is because the outboard motor is often used at sea, and the timing belt may be exposed to seawater. In other words, the seawater blown off by the timing belt belt adheres to the piston rod of the hydraulic damper, and this piston rod is corroded or salt deposits on the sliding surface, so that the piston sticks to the cylinder. It is.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and it is an object of the present invention to prevent a hydraulic damper from malfunctioning when a tensioner of an automobile engine is used for an outboard motor. With the goal.

[0008]

In order to achieve this object, a timing belt tensioner for an outboard motor according to the present invention rotatably supports a roller attached to a timing belt and swingably supports an engine body. Tensioner for a timing belt, comprising: a support member that has been moved, a spring member that urges the support member toward the timing belt, and a hydraulic damper that includes a hydraulic cylinder having one end of a piston rod abutted against the support member. The piston rod of the hydraulic damper is directed to the rear side in the running direction of the timing belt from the contact portion between the roller and the timing belt.

According to the present invention, the seawater blown off by the timing belt scatters in a direction away from the piston rod of the hydraulic damper.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of an outboard motor according to the present invention will be described below in detail with reference to FIGS. 1 is a side view of an outboard motor according to the present invention, FIG. 2 is an enlarged side view showing an engine part, FIG. 3 is a plan view of the engine, and FIG.
Is an enlarged view of the tensioner, which is drawn with the interior partially broken.

In these figures, what is indicated by reference numeral 1 is an outboard motor according to this embodiment. Reference numeral 2 denotes an upper casing of the outboard motor 1, 3 denotes a lower casing, 4 denotes a propeller, 5 denotes a tilt mechanism, 6 denotes an upper cowling, 7 denotes a lower cowling, and 8 denotes a hull.

The upper casing 2 has an engine 11 mounted on its upper end via a guide exhaust 2a. The engine 11 is a four-stroke V-type DOHC six-cylinder engine, and includes a cylinder body 12 and a crankcase 1.
3 support the crankshaft 14 (see FIG. 3) so that the axial direction thereof is directed in the vertical direction.
Is mounted in a state where it is released toward the rear of the outboard motor.

As shown in FIG. 3, the cylinder head 15 of the engine 11 has an intake device 16 to be described later connected to an end outside the V bank. 3, reference numeral 17 denotes a crankcase cover attached to the front side of the outboard motor of the crankcase 13, and reference numeral 18 denotes a head cover.

The intake device 16 is provided for each bank of the engine 11. An intake silencer 21 disposed in front of the engine 11 and an intake silencer 21
An intake pipe 22 extending rearward from the side of the engine 11;
A rear end (downstream end) of the intake pipe 22 is connected thereto, and is constituted by a throttle valve device 23 fixed to the cylinder head 15 and the like. ing.

As shown in FIG. 2, the intake silencer 21 is formed so as to extend vertically in front of the engine 11 and is supported by the crankcase cover 17.
The intake pipe 22 is formed integrally with an outer end of the intake silencer 21 in the left-right direction. The intake pipes 22 are formed for the respective cylinders and arranged vertically. That is,
The three intake pipes 22 are connected to one intake silencer 21, and the intake air is guided to the throttle valve device 23 via these intake pipes 22. Note that an intake inlet 21a (see FIG. 2) of the intake silencer 21 is formed so as to suck air from a space between the three intake pipes 22.

The throttle valve device 23 has a throttle valve 24 (see FIG. 2) and an injector 25 (see FIG. 3) for each cylinder. That is, the throttle valve 2
Four and four injectors 25 are arranged side by side in the vertical direction. The injector 25 injects fuel into the intake passage. Fuel is supplied from a vapor separator tank indicated by reference numeral 26 in FIGS. 2 and 3 by a high-pressure pump (not shown) in this tank.

As shown in FIG. 3, a timing belt 31 for transmitting the rotation of the crankshaft 14 to a valve train (not shown) in the cylinder head 15 is provided at the upper end of the engine 11.
, A flywheel magneto 32 and an engine cover 33 that covers the upper end of the engine body from above together with these two members. The valve gear has a well-known structure, and has a driven pulley 35 fixedly attached to an exhaust camshaft 34 and the timing belt 31
When the driven pulley 35 rotates, the exhaust camshaft 34 and the intake camshaft (not shown) rotate synchronously by the interlocking chain at the lower end, and the intake camshaft 34 and the intake valve (not shown) are rotated. The exhaust valve is driven.

The timing belt 31 is connected to the crankshaft 14.
Drive pulley 36 fixed to the exhaust camshaft 3 of both banks
The tensioner 37 is wound around the driven pulleys 35 provided on the right side of the outboard motor 4 on the right bank of the outboard motor of the cylinder body 12. The rotation direction of the timing belt 31 is clockwise in FIG.

As the tensioner 37, the one used for an automobile engine is diverted. As shown in FIG. 4, a roller 38 abutting on the timing belt 31 and a roller 38 disposed inside the roller 38 are provided. A support member 40 rotatably supported by a bearing 39, and a cylinder member 1 disposed between the support member 40 and the cylinder body 12.
2, a hydraulic attenuator 41, an oscillating shaft 42 that penetrates through the support member 40 and the hydraulic attenuator 41 and is screwed to the cylinder body 12.

The roller 38 is formed as an outer ring of the bearing 39, and is provided with electroless nickel plating over the entire outer peripheral surface. The support member 40 is formed of a sintered material, and a swing shaft 42 is slidably fitted at a position eccentric with respect to the axis of the roller 38, and the swing shaft 42 swings on the cylinder body 12. Have been supported. The upper surface of the support member 40 is subjected to a so-called parkerizing treatment to improve corrosion resistance.

The support member 40 has a spring receiving recess 43 formed therein, and a first compression coil spring 44 for urging the roller 38 toward the timing belt 31 together with the support member 40 is loaded. are doing. To elaborate,
The pin 45 of the hydraulic attenuator 41 faces the recess 43, and the pressing element 46 in contact with the pin 45 and the recess 4
The first compression coil spring 44 is elastically mounted between the first compression coil spring 44 and the third pressure receiving surface 43a. The first compression coil spring 44 urges the support member 40 together with the roller 38 in the counterclockwise direction about the swing shaft 42 in the drawing, and the roller 38
Is pressed against the timing belt 31.

The hydraulic attenuator 41 integrally forms an arm 47 projecting laterally from the roller 38 and has a hydraulic cylinder 48 formed therein. The arm 47 is inserted through the projecting end of the arm 47. It is fixed to the cylinder body 12 by the fixing bolt 49 and the swing shaft 42.
The hydraulic cylinder 48 is formed such that a piston rod 50 protrudes from one end, and is filled with hydraulic oil in the cylinder and a second compression coil spring for urging the piston 51 in a direction in which the piston rod 50 protrudes. 52 is loaded.

The piston 51 is provided with a throttle 55 communicating between two oil chambers 53 and 54 in the cylinder defined by the piston 51. The hydraulic oil corresponding to the increase or decrease in the volume of the piston rod 50 penetrating through one oil chamber 54 enters and exits an oil tank (not shown).

The hydraulic cylinder 48 is provided with a piston rod 50 at the rear side in the running direction of the timing belt 31 from the contact portion between the roller 38 and the timing belt 31.
The protruding end of the piston rod 50 is brought into contact with a pin 56 formed integrally with the support member 40. The range of the abutting portion is indicated by reference numeral A in FIG.

According to the tensioner 37 configured as described above, the support member 40 advances toward the timing belt 31 by the elastic force of the first compression coil spring 44, and the roller 38
Is pressed against the timing belt 31. If the tensioner 37 vibrates due to rotation fluctuation during the operation of the engine, the vibration is attenuated by the hydraulic damper 41.
That is, when the tensioner 37 retreats, the support member 4
0 pin 56 is the piston rod 50 of the hydraulic cylinder 48
Is pressed, and the hydraulic oil flows through the throttle 55 of the piston 51 to generate resistance. When the tensioner 37 moves forward, the piston 51 is pressed by the second compression coil spring 52, and the piston rod 50 comes into contact with the pin 56 of the support member 40.

For this reason, in the tensioner 37, the timing belt 31 can be pressed and the vibration can be attenuated by the elastic force of the first compression coil spring 44.
Even if the inter-axis distance between the crankshaft 14 and the exhaust camshaft 34 changes, a constant tension can always be applied to the timing belt 31.

During sailing, seawater may enter the cowling, and seawater adhering to the timing belt 31 may be mist-shaped and scattered in the engine cover 33. However, in the tensioner 37 described above, the piston rod 50 of the hydraulic damper 41 is
The seawater blown off by the timing belt 31 is scattered in a direction away from the piston rod 50 of the hydraulic damper 41 and the piston Rod 5
0 does not adhere. Therefore, when diverting the tensioner of the automobile engine to the outboard motor 1, it is possible to prevent the hydraulic damper 41 from malfunctioning.

The tensioner 3 according to this embodiment
In No. 7, an electroless nickel plating is applied to the outer peripheral surface of the roller 38, and since the plating layer is formed hard and deep on the surface with which the timing belt 31 contacts, in other words, the surface that is easily worn, corrosion is caused by seawater. Not only can be prevented, but also the wear resistance can be improved. Since the upper surface of the support member 40 is also subjected to a surface treatment that increases the corrosion resistance, the corrosion resistance of the tensioner 37 can be further increased.

[0029]

As described above, according to the present invention, the seawater blown off by the timing belt is scattered in a direction away from the piston rod of the hydraulic damper, so that the seawater adheres to the piston rod. Can be prevented. For this reason, when diverting the tensioner of the automobile engine to the outboard motor, it is possible to prevent the hydraulic damper from malfunctioning. As a result, the tension of the timing belt can be kept constant, and the durability of the timing belt can be improved.

[Brief description of the drawings]

FIG. 1 is a side view of an outboard motor according to the present invention.

FIG. 2 is an enlarged side view showing an engine part.

FIG. 3 is a plan view of the engine.

FIG. 4 is an enlarged view showing a tensioner.

[Explanation of symbols]

1 outboard motor, 31 timing belt, 38 roller
Reference numeral 40: a support member; 41, a hydraulic damper; 44, a first compression coil spring; 50, a piston rod;

Claims (1)

[Claims] 1. A support member rotatably supporting a roller attached to a timing belt and swingably supported by an engine body, a spring member for urging the support member toward the timing belt, and the support member. A timing belt tensioner including a hydraulic attenuator comprising a hydraulic cylinder having one end of a piston rod abutted thereon, wherein the piston rod of the hydraulic attenuator is disposed between an abutting portion of the roller and the timing belt. A timing belt tensioner for an outboard motor, wherein the tension belt is directed rearward in the running direction of the timing belt.