JP2001330075A - Shock absorber with height adjustment function - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To quickly detect overheating of a heater due to outgassing or the like, and to prevent seizure or burning of peripheral components from occurring. SOLUTION: An electric current is supplied when the vehicle height decreases, and heat is generated.
The heat medium causes the pressure medium to expand by heating, thereby increasing the pressure in the pressure chamber 17 and relatively displacing the cylinder 1 and the piston rod 2 in the direction in which the vehicle height increases. When the temperature rises above the set level, the relay 27 is turned off to cut off the current supplied to the heater 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shock absorber having a vehicle height adjusting function provided between a vehicle body and an unsprung member of an automobile.

[0002]

2. Description of the Related Art A shock absorber includes a cylinder and a piston rod having one end attached to a piston that slides in the cylinder and movably inserted into the cylinder. One is connected to the vehicle body while the other is connected to the unsprung member, so that a damping force against vibration of the unsprung member can be obtained.

On the other hand, a cylinder for adjusting the vehicle height is interposed between the shock absorber and the vehicle body, and when the vehicle height decreases, a pressure fluid is supplied from a pressure source to this cylinder to increase the vehicle height. In such a manner, the vehicle height can be adjusted as described above.

In this case, since a pump driven by the engine is used as the pressure source, the load on the engine is large and the fuel efficiency is deteriorated.

On the other hand, conventionally, a vehicle height adjusting section in which a pressure medium which changes gas and liquid is sealed in a pressure chamber is provided, and the vehicle is raised by heating the pressure medium using a heater. A shock absorber with a vehicle height adjustment function that adjusts the vehicle height in a direction has been proposed.

[0006]

However, in a conventional shock absorber with a vehicle height adjusting function using such a heater, although the pressure medium is sealed in the pressure chamber, the pressure medium is sealed due to an abnormality in the pressure chamber. In addition to gas leakage, the vehicle height may not rise due to overloading that exceeds the vehicle height adjustment capability.If the heater continues to generate heat in such a situation, damage to surrounding components may occur. For example, there is a problem that circuit components such as a semiconductor device for a vehicle height adjustment circuit are burned.

SUMMARY OF THE INVENTION The present invention solves the above-described problems, and quickly detects overheating of a heater due to outgassing or the like, and prevents such a situation in which seizure or burning of peripheral components can be avoided. It is an object of the present invention to obtain a shock absorber with a vehicle height adjustment function that can keep the vehicle.

[0008]

In order to achieve the above object,
A shock absorber with a vehicle height adjusting function according to the present invention is formed between a cylinder and a piston rod and a case, and receives pressure when a vehicle is lowered and generates heat when a vehicle height is lowered. And a heater that heats and expands the pressure medium to increase the pressure in the pressure chamber, and relatively displaces the cylinder and the piston rod in the direction in which the vehicle height increases. When the current exceeds the threshold, the relay is turned off to cut off the current supplied to the heater.

In the shock absorber with a vehicle height adjusting function according to the present invention, after the relay is turned off, even if the temperature sensor switch is closed, the current to the heater is cut off until the starter switch of the engine is turned on again. Is maintained.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a partially cutaway front view showing a shock absorber with a vehicle height adjusting function of the present invention. In the figure, reference numeral 1 denotes a cylinder serving as a main body of a shock absorber. One end of a piston rod 2 is attached to a piston that slides in the cylinder 1.

An eye 1a provided at the upper end of the cylinder 1 can be attached to the vehicle body.
An eye 2a provided on a lower cap (not shown) integral with the lower end of the spring can be attached to the unsprung member.

A rod guide 3 is fitted into a lower part of the lower end of the piston rod 2, and a holder 4 is inserted through the lower end of the piston rod 2 so as to abut the lower end of the rod guide 3. The holder 4 is fixed to the piston rod 2 together with the rod guide 3 by a nut 5 screwed into the lower end.

The lower end of the piston rod 2 and the holder 4 are provided with mounting holes for fitting a heater plug described later as a heater.

A lower end of a case 6 is hermetically fixed to an upper surface of an outer peripheral portion of the holder 4. A substantially upper half of the case 6 covers an outer periphery of a substantially lower half of the cylinder 1 at a predetermined gap G. ing.

A holder, a collar, and a sealing member (all not shown) are provided at the upper end of the case 6 so as to airtightly close the gap G.

For this reason, the case 6 can be slid airtightly with respect to the cylinder 1.

The lower end of an outer shell 7 surrounding the outer periphery of the case 6 is attached to the outer periphery of the holder 4, and the upper end of the outer shell 7 is fixed to the collar.

At the lower end of the outer shell 7, the lower cap integrally having the eye 2a is attached.

Further, a cylindrical resin cover 8 is attached to the outer periphery of the outer shell 7 by screws 9, and the upper end of the resin cover 8 is fixed to the collar (not shown).

The screw 9 is inserted into a boss member 10 whose one end is fitted into a mounting hole at the lower part of the resin cover 8, and the tip of the screw 9 is screwed into the outer shell 7.

A rectangular frame portion 8a as viewed from the side is projected below the resin cover 8, and one end of the circuit board 11 is horizontally held in the frame portion 8a as shown in FIG. Is fixed to the boss portion 14 by screws 13.

The mounting plate 12 is made of a metal material such as aluminum having good heat conductivity, and has a heat radiating effect of a heater current control FET (field effect transistor) 15 mounted on the mounting plate 12. .

The FET 15 is connected to a circuit pattern on the circuit board 11.

Reference numeral 16 denotes a heater plug as a heater for heating the pressure medium, which penetrates the resin cover 8 and the outer shell 7 in the frame portion 8a, and is inserted into the end of the piston rod 2 and the mounting hole of the holder 4. It is held horizontally.

The holder 4 has a notch 4a opening upward.
The end of the heating rod 16a of the heater plug 16 faces the notch 4a.

Further, the notch 4a communicates with a pressure chamber 17 in the case 6 below the cylinder 1, and the gap G also communicates with the pressure chamber 17.

In the pressure chamber 17, gas-liquid changes, for example,
A low-boiling pressure medium, such as the CFC substitute gases R134a and R152a, is sealed, and is directly heated by the heating rod 16a of the heater plug 16 to expand and act to increase the internal pressure of the pressure chamber 17.

The rise of the internal pressure causes the cylinder 1 to be pushed upward with respect to the piston rod 2.

Further, the heater plug 16 and the pressure chamber 1
The pressure medium 7 and the pressure medium constitute a vehicle height adjusting means A together with a magnet and a reed switch described later.

A reed switch 18 and a lead wire 19 for transmitting an on / off signal by the on / off operation of the reed switch 18 are embedded in the resin cover 8 from the middle to the lower portion.

Then, for the reed switch 18,
A cylinder cover 20 whose upper part is attached to the cylinder 1 and covers the outer peripheral surfaces of the cylinder 1 and the resin cover 8.
A magnet 21 is mounted inside the box, and the magnet 21 is vertically opposed to the reed switch 18.

A cord 23 for supplying a current from an external power supply to the heater plug 16 and the like is inserted into a part of the frame portion 8a through a rubber bush 22 penetrating inside and outside the frame portion 8a.

Although not shown, a thermistor for compensating the temperature of the circuit is provided in the frame 8a as required.

A resin lid 24 covers the opening of the frame 8a, and is fixed by screws 25.

FIGS. 2 and 3 are a front view and a partially cutaway side view conceptually showing the positional relationship between the reed switch 18 provided on the resin cover 8 and the magnet 21 provided on the cylinder cover 20. It is.

Here, the reed switch 18 is arranged in a direction in which the reed axis becomes horizontal.
8 is connected via a lead wire 19 to an electric circuit section 26 including the FET 15, thermistor, resistor and the like.

As the magnet 21, a flexible and thin rubber magnet is used as a whole, which is adhered to the inner peripheral surface of the cylinder cover 20.

As shown in the figure, the magnetizing pattern of the magnet 21 is divided into an S pole and an N pole in the direction shown in the drawing with respect to the lead axis direction P of the reed switch 18. Is subjected to single-sided two-pole magnetization.

That is, the magnet 21 has a predetermined length in the axial direction of the piston rod 2, and has S and N poles formed in a direction substantially orthogonal to the axial direction, and the S and N poles are formed. The surface faces the reed switch 18.

FIG. 5 shows a circuit for preventing overheating of the heater plug 16, and FIG. 6 shows a timing chart of signals in respective parts of the circuit.

In FIG. 5, reference numeral 27 denotes a heater plug 16
A relay switch 27a of the main relay 27 is connected between the heater plug 16 and the ignition power supply IG via a fuse 30, and a relay coil 27b is connected to a temperature sensor switch. 28 and an ignition power supply IG are connected via a starter switch 31 of the engine.

The heater plug 16 is connected to a terminal of the relay coil 27b opposite to the terminal to which the temperature sensor switch 28 is connected via a backflow prevention diode 29.

Here, the temperature sensor switch 28 constantly monitors the temperature of the heater plug 16 and opens when the temperature of the heater plug 16 exceeds a set value.
On the other hand, for example, a temperature-sensitive reed switch is used which has a function of closing when the temperature drops below a set value.

This temperature-sensitive reed switch is formed by attaching a temperature-sensitive ferrite between a pair of ferrite magnets, and functions to change the magnetic field of the ferrite magnet with respect to the reed switch 18 according to the temperature detected by the temperature-sensitive ferrite. I do.

The temperature sensor switch 28 prevents overheating of the heater plug 16 as described later.

Next, the operation will be described. First, when the load acting on the vehicle body is small, the distance between the vehicle body and the unsprung member is kept sufficiently large, and as shown in FIG. Project from the inside of the cylinder 1 in the extension direction by a considerable amount.

Therefore, the resin cover 8 on the piston rod 2 side is connected to the cylinder cover 20 attached to the cylinder 1.
It protrudes greatly from the inside in the extension direction.

As a result, the magnet 21 is largely separated from the reed switch 18 in the vertical direction, and the reed switch 18 is not affected by the magnetic field of the magnet 21 (or is less affected by the magnetic field), and maintains the switch-off state. I have.

In the off state of the reed switch 18,
Since the FET 15 is off in the circuit, the heater plug 16
Is cut off, and the heating of the heater plug 16 is not controlled.

On the other hand, the load acting on the vehicle body increases,
When the vehicle body falls below the set level, the piston rod 2 enters the cylinder 1 and the resin cover 8 also enters the cylinder cover 20 as shown in FIG. Are turned on under the influence of the magnetic field of the magnet 21.

As a result, the FET 15 is turned on, and a current is supplied to the heater plug 16 from an external power supply.
The heating rod 16a of the heater plug 16 is heated under the control by the ET 15.

Since the heating rod 16a faces the notch 4a of the holder 4 and directly heats the pressure medium in the pressure chamber 17, the pressure medium rapidly expands by this heating, and the internal pressure of the pressure chamber 17 rises. Let it.

The cylinder 1 moves upward with respect to the case 6 on the piston rod 2 side due to the increase in the internal pressure of the pressure chamber 17.

For this reason, the vehicle body to which the eye 2b is attached rises with respect to the unsprung member to which the eye 2a is attached, and this rise continues until the reed switch 18 is turned off by being no longer affected by the magnet 21. As a result, the vehicle stops at the set level rising position.

In this way, the vehicle body is held at a predetermined level.

In such a shock absorber, a thin reed switch 18 is attached to the magnet 21.
Since a rubber magnet that generates a magnetic field sufficient to turn on the cover is used, it can be easily mounted on the inner periphery of the cylinder cover 20 and is not bulky. It is not necessary to make the outer diameter of the cylinder 20 larger than necessary.

The rubber magnet is a composite of a ferrite magnet powder and a synthetic rubber, imparts strong magnetic anisotropy, and has flexibility and elasticity.

The present invention has a circuit for preventing overheating of the heater plug 16 as shown in FIG.

When the pressure medium is reduced due to gas leakage due to an abnormality in the pressure chamber 17, the rod portion 16a of the heater plug 16 does not come into contact with the pressure medium, and the heat generation temperature rises rapidly during the vehicle height adjustment operation. I do.

Also, in the case of overloading, the reed switch 1
8 keeps on and the heater is overheated. In such a case, if this temperature is detected by the temperature sensor switch 28 and the current is interrupted, overheating of the heater plug 16 and peripheral components can be prevented.

That is, in the circuit of FIG.
As shown in FIG. 6A, when the ignition power supply IG is turned on and then the starter switch 31 of the engine is closed as shown in FIG. 6B, when the temperature of the heater plug 16 is lower than the set value, The main relay 27 is shown in FIG.
It operates as shown in FIG.

That is, a current flows through the relay coil 27b via the starter switch 31 and the temperature sensor switch 28.

Therefore, the relay switch 27a is turned on, the current is supplied from the ignition power supply IG to the heater plug 16 via the fuse 30, and the heater plug 16 generates heat to heat the pressure medium.

Thereafter, even if the starter switch 31 returns to off, the relay switch 27a is kept on by the self-holding circuit.

On the other hand, if the temperature near the heater plug in the pressure chamber 17 or directly the temperature of the heater plug 16 rises above the set level due to the above-mentioned outgassing or overloading, the temperature sensor switch 28 is FIG.
It is automatically opened as shown in (d).

Therefore, the supply current is cut off and the relay coil 27b is deenergized, the relay switch 27a is opened, and the current supply from the ignition power supply IG to the heater plug 16 is cut off.

Accordingly, the heater plug 16 does not become overheated any more, but gradually lowers below the set temperature.

In the above-described embodiment, the case where a magnet subjected to single-sided two-pole magnetization is used as the magnet 21 is shown. However, in the present invention, the magnet 21 basically has a predetermined length in the axial direction of the piston rod 2. The surface on which the S and N poles are formed in a direction substantially orthogonal to the axial direction is the reed switch 1.
Since it is only necessary to face the magnet 8, it is also possible to use a magnet that has been subjected to axial (two-sided) two-pole magnetization.

Further, at the time of assembling the shock absorber, positioning marks are provided on the cylinder cover 20 and the resin cover 8 to which the magnets 21 are attached so that the magnets 21 can face the reed switch 18. Is desirable.

[0070]

As described above, according to the present invention, the cylinder and the piston rod are formed between the case and
An electric current is supplied when the vehicle height decreases and heat is generated when the vehicle height is lowered, and the pressure medium is heated and expanded by this heat to increase the pressure in the pressure chambers. A heater for relatively displacing in the ascending direction, so that the temperature sensor switch turns off the relay when the temperature of the heater rises above the set level, thereby interrupting the current supplied to the heater. Therefore, when the pressure medium is outgassed in the pressure chamber or when the pressure medium is overloaded, the heater can be prevented from being overheated, and therefore, seizure and burnout of peripheral parts of the heater can be prevented. The effect is obtained.

Further, according to the present invention, after the relay is turned off, even if the temperature sensor switch is closed, the current to the heater is kept shut off until the starter switch of the engine is turned on again. In addition, the vehicle height can be adjusted only immediately before the vehicle starts running, and the danger caused by the vehicle height adjustment during vehicle running can be avoided.

[Brief description of the drawings]

FIG. 1 is a partially cutaway front view of a shock absorber with a vehicle height adjusting function according to an embodiment of the present invention.

FIG. 2 is a front view of a shock absorber with a vehicle height adjusting function conceptually showing a positional relationship between a magnet and a reed switch in FIG. 1;

3 is a side view of the shock absorber with a vehicle height adjusting function of FIG.

FIG. 4 is a side view showing an operation state of the shock absorber with a vehicle height adjusting function of FIG. 3;

FIG. 5 is a circuit diagram showing a circuit for preventing overheating of a heater plug according to the present invention.

FIG. 6 is a timing chart showing signals of respective parts of the circuit of FIG. 5;

[Explanation of symbols]

 1 Cylinder 2 Piston rod 6 Case 16 Heater plug (heater) 17 Pressure chamber 18 Reed switch 28 Temperature sensor switch

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yukio Hayakawa 1-4-1 Chuo, Wako-shi, Saitama F-term in Honda R & D Co., Ltd. (Reference) 3D001 DA03 DA15 DA16 DA15 EA01 EA45 EB00 EC09 ED02 3J069 AA09 BB10 CC40 DD11 DD13 EE70

Claims (2)

[Claims] 1. A cylindrical case having one end hermetically connected to a piston rod and the other end slidably in contact with the outer periphery of a cylinder, and formed between the cylinder and the piston rod and the case. A pressure chamber containing a pressure medium,
When a vehicle height is lowered, an electric current is supplied to generate heat, and the heat is used to heat and expand the pressure medium to increase the pressure in the pressure chamber, thereby relatively displacing the cylinder and the piston rod in a direction in which the vehicle height increases, and a heater. A shock absorber with a vehicle height adjusting function, comprising: a temperature sensor switch for turning off a relay to cut off a current supplied to the heater when the temperature of the heater rises above a set level. 2. After the relay is turned off, even if the temperature sensor switch is closed, the cut-off state of the current to the heater is maintained until the starter switch of the engine is turned on again. Shock absorber with vehicle height adjustment function described in 1.