JPH0242218A - Viscous fluid coupling - Google Patents

Abstract

PURPOSE:To reduce useless power for driving an input shaft by fitting a disc on an output shaft which rotates coaxially with the input shaft, and by charging viscous oil between the disc and one end face of a piston. CONSTITUTION:A casing 1a is fixed to an input shaft 1a associated with an engine or the like. A disc 3a is fitted on an output shaft 3, and highly viscous oil such as silicone oil or the like is charged in a chamber 1f. The pressure of viscous oil in the chamber 1f causes the disc 3a to move away from one end face 2b of a piston 2 as the rotational speed of the input shaft 1a increases. Even though the rotational speed of the input shaft 1a becomes high, the rotational speed of the output shaft does not increase so high. Thus, it is possible to reduce useless power for driving the input shaft.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a viscous fluid coupling for use as a fan coupling or the like in an internal combustion engine.

[Prior Art] In order to cool the internal combustion engine itself, an internal combustion engine used in an automobile cools its cooling water using an air flow generated by the drive of a fan. The system employs a configuration that is driven by.

However, when the fan driven by the internal combustion engine is directly connected and driven by the internal combustion engine, the fan's cooling usage becomes excessive when the internal combustion engine rotates at high speed. This means that the output power from the internal combustion engine is wasted.

For this reason, conventionally, a fan coupling is interposed between the fan driven by the internal combustion engine and the output shaft of the internal combustion engine. The structure is such that the rotation speed does not reach a certain level.

That is, the configuration of the fan coupling is such that the casing of the fan coupling is driven by an internal combustion engine, the casing is provided with a disc or side wall, and the disc or side wall is connected to the casing of the fan coupling. A viscous oil is interposed between the disc and another disc facing the fan Φ coupling and fitted onto the output shaft of the fan Φ coupling, and a fan for cooling the internal combustion engine is linked to the output shaft.

With this configuration, when the internal combustion engine drives the fan coupling, the fan is driven by the viscous force of the viscous oil filled in the fan coupling. Ru.

Therefore, as the rotational speed of the internal combustion engine increases, the shear generated in the viscous oil in the fan-coupling when driving the fan through the viscous oil increases. The rotational speed remains at a low rotational speed below the rotational speed directly connected to the rotational speed of the internal combustion engine.

[Problems to be Solved by the Invention] However, in the conventional configuration of the fan coupling described above, the disc gap between the input shaft side and the output shaft side where the viscous leakage body is interposed is constant. When the internal combustion engine rotates at high speed, the driving force of the fan through the viscous fluid is still large, and the fan is rotated to an unnecessary rotation speed during high speed rotation, resulting in wasted output power of the internal combustion engine. There is a problem that is causing this.

An object of the present invention is to provide a viscous fluid joint that completely solves the above-mentioned problems.

[Features for Solving the Problems] The invention of PiSl has the following features.

In the casing fixed to the input shaft, a piston is fitted into a cylinder cut in the axial direction of the input shaft so as to be able to slide in the axial direction; A spring biasing force is applied toward a disc inside the chamber provided in the casing, and the disc is fitted onto an output shaft that rotates on the same axis as the input shaft.

A gap between the piston and the end surface facing the disc is filled with viscous oil.

As a result, when the rotation speed of the input shaft increases, the pressure of the viscous oil filled between the disk and the end face of the piston increases, and this increased pressure suppresses the piston until it reaches a position in equilibrium with the spring force. let

In other words, the gap between the disk and the piston end surface becomes wider due to the piston's suppressed shift, which weakens the viscous force in the rotational force direction of the viscous oil that is generated between the piston end surface and the disk. As a result, above a predetermined rotational speed, the viscous force in the rotational direction between the piston end face and the disc becomes almost zero, and the remaining wall part of the casing faces the other wall part. The rotational force on the input shaft side is transmitted to the output shaft side via the viscous oil between the disc part and the disc part.

Regarding the second invention, in addition to the first invention, a displacement chamber is formed by a cylinder and a piston, separately from the part enclosing the disc, and the disc is disposed inside and the viscous oil is disposed inside. The filling chamber and the displacement chamber are communicated through a hole bored at a position with a smaller diameter than the outer diameter of the disk.

As a result, as the rotational speed of the input shaft increases, the pressure of the viscous oil increases as in the first invention, and this pressure increase pushes the piston to move against the spring biasing force, causing the inside of the room to move. The viscous oil will be absorbed into the displacement chamber.

This means that as the rotation of the input shaft increases, the amount of viscous oil in the chamber decreases, and the wetted area between the casing wall and the disk in the chamber due to the viscous oil decreases, causing the input shaft to move from the output shaft to the output shaft. The amount of torque transmitted to the side will decrease.

In addition, in the above action, the viscous oil in the portion located on the outer diameter side from the position of the perforation does not flow out from the perforation to the displacement chamber due to the rotational centrifugal force, so the viscous oil in that portion is It contributes to torque transmission from the casing side to the disk side.

[Example] Hereinafter, the present invention will be explained based on Examples.

FIG. 1 shows a side sectional view of a viscous fluid joint as an embodiment of the present invention.

In FIG. 1, a casing 1 is fixed to an input shaft 1a that is linked to an engine, etc., and a circular plate 3a is fitted to an output shaft 3 that is rotatably supported by the casing l and linked to a cooling fan, etc.
A chamber 1f provided in the casing 1 and enclosing the disc 3a is filled with high viscosity oil such as silicone oil, and a donut-shaped cylinder 1b cut in the casing 1 is capable of sliding in the axial direction. The same donut-shaped piston 2 is fitted into the piston 2, and the spring 2a applies a biasing force to the piston 2 in the direction of the disc 3a.

Note that the chamber 1f communicates with the atmosphere via a breather 1e, and the chamber 2C communicates with the atmosphere via a breather (not shown). Further, in actual design, the breather 1e is provided at a position as close to the rotation center of the input shaft 1a as possible.

The operation of the configuration of the embodiment of the present invention described above will be explained below.

When the input shaft 1a rotates, the casing 1 also rotates, and due to the centrifugal force of the rotation, the viscous oil filling the chamber If is
Filling the gap IC1 between the casing 1 and the disk 3a or the gap 1d between the disk 3a and the piston 2, as a result,
Viscous resistance in the rotational direction occurs in the viscous oil in the gaps 1c and 1d, and the viscous resistance rotates the disk 3a, thereby driving the output shaft 3.

In the above action, when the casing 1 rotates, the pressure of the viscous oil increases due to the centrifugal force of the rotation, and the pressure increase is proportional to the square of the rotational speed of the casing 1.

When the pressure of the viscous oil increases in this way, the piston 2 is forced to shift to the right by the pressure, and the shifting position is determined by the value of the increased pressure and the spring constant of the spring 2a.

That is, since the pressure of the viscous oil increases in proportion to the square of the rotation speed in the casing 1, the piston 2 moves to the right in proportion to the square of the rotation speed in the input shaft 1a. and the end surface 2b of the piston 2
This means that the gap 1d between the two increases in proportion to the square of the rotational speed of the input shaft 1a.

Moreover, in this case, the magnitude of torque transmission from the casing 1 to the disc 3a has a property of decreasing in proportion to the gap IC or the interval 1d.

As a result, as the casing 1 rotates, the amount of torque transmitted between the end surface 2b of the piston 2 and the disk 3a through the viscous oil becomes smaller as the rotational speed of the input shaft 1a increases. Eventually, when the rotational speed reaches a predetermined rotational speed or higher, almost no torque is transmitted, and at rotational speeds higher than that, the gap between the casing 1 and the disk where the piston 2 is not present remains. 3a, torque is transmitted from the casing 1 side to the disc 3a via the viscous oil therebetween.

Moreover, when the rotational speed of the input shaft 1a decreases, again,
The pressure of the viscous oil returns to the original pressure corresponding to each rotational speed, and as a result, the viscous oil returns to the position corresponding to the original rotational speed, and the viscous oil is released by gravity. 1eJ! It accumulates in the lower position.

Although the piston 2 in the above embodiment has a donut shape, a plurality of pistons each having a normal circular cross section are arranged at equally divided positions on the circumference of the casing 1. It is also possible to have a configuration in which

However, if the piston 2 is shaped like a donut as shown in Figure 1, the end surface of the piston 2 facing the first disk 3a
There is an advantage that b can be effectively widened.

FIG. 2 shows another embodiment of the present invention with respect to FIG. 1.

The first difference in the configuration of FIG. 2 from FIG. 1 is that there is a gap 1d' (
The wall surface 1g forming the gap 1d (corresponding to the gap 1d in FIG. 1) is the end surface 2b of the piston 2 in FIG. 1, but in FIG. 2 it is the wall surface Ig fixed to the casing l'. It is something that

The second difference between FIG. 2 and FIG. 1 is that a cylinder 1b is cut out on the right side of the wall surface 1g, and the piston 2 is slidably fitted into the cylinder 1b. A spring 2a is attached to the piston 2 toward the displacement chamber 2d.
The perforation 1h is interposed between the gap 1d' and the displacement chamber 2d, and the diameter of the perforation 1h is shorter than the outer diameter of the disk 3a. There is.

Other parts in FIG. 2 are the same as in FIG. 1, and members with the same reference numerals as in FIG. 1 in FIG. 2 indicate the same materials as in FIG. 1.

The operation of the configuration shown in FIG. 2 will be explained below.

As the input shaft 1a rotates, the pressure of the viscous oil increases in the chamber lf, as in FIG.
The pressure of the viscous oil in d also increases.6 As a result, the increased pressure in the displacement chamber 2d presses and shifts the piston 2 to the right against the urging force of the spring 2a. Pushed away room 2d
The viscous oil in the chamber lf flows into the chamber lf.

As a result, the viscous oil that filled the chamber lf when the rotational speed of the input shaft 1a was low gradually forms a cavity radially outward from the center of rotation as the rotational speed increases. As can be understood from the above explanation, increases in proportion to the square of the rotational speed of the input shaft 1a, and when the rotational speed reaches a predetermined value, the gaps IC and ld' up to the diameter where the perforation ih is located increase. The viscous oil in the air will be replaced by air.

However, above that predetermined rotational speed.

The viscous oil that exists on the outer diameter side of the hole 1h moves radially inward than the hole ih due to the rotational centrifugal force! Therefore, at the predetermined rotational speed or higher, the viscous oil remains filled radially outward from the perforation 1h, and the gap 1c from the casing 1° remains constant, and the gap 1c remains constant. Torque is transmitted to the disc 3a via the viscous fluid present at and Ld'.

In addition, in the above action, from the casing 1' to the disc 3a
The capacity of torque transmission to the disc 3a is proportional to the area (wetted area) of the portion of the disc 3a where the viscous oil exists in the gap 1c or ld'.

Therefore, as the rotational speed of the input shaft 1a increases,
As it rises, the wetted area of viscous oil between the disc 3a and the casing 1' decreases, which means that the input shaft 1a
As the rotational speed of the input shaft 1a increases, the rotational speed difference between the input shaft 1a and the output shaft 3 increases, and compared to the increase in the rotational speed of the input shaft 1a, the rotational speed of the output shaft 3 does not increase as much. Become.

Further, when the input shaft 1a reaches the above-mentioned predetermined rotational speed or higher,
Disc 3 from the casing 1' side via viscous oil at the outer diameter part from the perforation 1h in the gaps 1c and ld'
Torque is transmitted to the a side.

In addition, in the embodiments shown in FIGS. 1 and 2 above, the load that is interlocked with the output shaft 3 is a load other than the cooling fan,
For example, a load such as a hydraulic pump that does not need to increase the amount of oil in proportion to the rotational speed of the human-powered shaft 1a may be linked.

[Effects of the Invention] As can be clearly seen from the above explanation, the effects of the present invention are as follows.

1) In the first invention in the EIRI diagram, the chamber if
The pressure of the viscous oil at increases the rotational speed of the input shaft 1a, and acts to separate the end surface 2b of the piston 2 from the disc 3a, widening the gap 1d for the viscous oil that contributes to torque transmission. As a result, even if the rotational speed of the input shaft 1a increases to high speed, it is possible to design the output shaft 3 so that the rotational speed of the output shaft 3 does not increase by that much.

This is because conventionally, power was unnecessarily transmitted from the input shaft 1a side to the output shaft 3 side.
This makes it possible to reduce unnecessary excessive power transmission, and contributes to reducing the wasted power that drives the input shaft 1a.

2) In the second invention in FIG. 2, the input shaft 1a
As the rotational speed increases, the viscous oil in the chamber 1f is displaced into the displacement chamber 2d, and the wetted area between the disc 3a and the casing l' decreases.

2. Similar to the effect of the first invention, it is possible to suppress the rotational speed of the output shaft 3 to be lower than the rotational speed hill 4 of the input shaft 1a.

[Brief explanation of the drawing]

FIG. 1 shows a side cross-sectional view of a viscous fluid joint as one embodiment of the present invention, and FIG. 2 shows a side cross-sectional view of a viscous fluid joint of another embodiment of the present invention. It is something. The main symbols used in the examples are as follows. 1 and 1゛: Casing, 1a: Input shaft 1b = cylinder, IC11d, 1d': gap, lf: chamber, 1g: side wall, 1h: perforation, 2: piston,
2a spring, 2d: displacement chamber, 3: output shaft, 3a: disc. Patent applicant Sanwa Seiki Co., Ltd. Representative Etsushi Nishikai Figure 1

Claims (1)

[Claims] 1. A piston fits into a cylinder cut in the axial direction of the input shaft in a casing fixed to the input shaft so as to be able to slide in the axial direction. , a spring biasing force is applied in the axial direction toward the side of a disk inside the chamber provided in the casing, and the disk is fitted onto the output shaft rotating coaxially with the input shaft, and A disk and
A viscous fluid joint characterized in that viscous oil is filled between the piston and the end surface facing the disk. 2. A chamber is provided in the casing fixed to the input shaft, enclosing a disk fitted to the output shaft that rotates coaxially with the input shaft, and the side wall of the chamber is parallel to the disk. A cylinder is provided facing the casing, and on the axially opposite side of the chamber with the side wall as a boundary, a cylinder is fixed to the casing and fitted with a piston so as to be slidable in the axial direction. A spring biasing force is applied to the piston toward a displacement chamber formed between the side wall and the piston in the cylinder, and a hole is bored in the side wall at a position on a diameter shorter than the outer diameter of the disk. The perforation communicates the chamber with the displacement chamber, and the chamber is filled with viscous oil in an amount equal to or less than the volume of the chamber when the input shaft is not rotating. Viscous fluid fitting.