Brakes – Internal-resistance motion retarder – With heat exchanger
Reexamination Certificate
1998-10-05
2001-01-09
Schwartz, Christopher P. (Department: 3613)
Brakes
Internal-resistance motion retarder
With heat exchanger
Reexamination Certificate
active
06170621
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a vehicular damper with a vehicle height adjusting function which is applied to a vehicle such as a motor vehicle. In this specification, the term “vehicular damper” means a damper for use in a vehicle.
2. Description of the Related Art
A vehicular damper is provided with a damper main body, and a damper rod which is inserted into the damper main body so as to be movable up and down. One of the damper main body and the damper rod is connected to an unsprung member, and the other thereof is connected to a vehicle body so that a damping force against the vibrations of the unsprung member can be obtained.
In case a function of adjusting the vehicle height (also called a vehicle height adjusting function) is added to the damper, the following arrangement is employed. Namely, a cylinder for adjusting the vehicle height is interposed between the vehicle body and the damper. A pressure fluid from a pressure source is supplied to the cylinder, whereby the vehicle height is adjusted. As this pressure source, a pump to be driven by an engine of the vehicle is normally used. In this arrangement, however, the energy consumption increases and the specific fuel consumption becomes poor. As a solution, in order to enable to supply the pressure fluid without consuming the energy of the engine, there is proposed in Japanese Published Unexamined Patent Application No. 150615/1997 an art in which a heat-pressure conversion type of pressure source utilizing the waste heat of an engine is used.
This pressure source is provided with: a pressure chamber hermetically containing therein a pressure medium which changes its state between a liquid state and a gaseous state; a heating chamber for passing therethrough a heating medium which is heated by the heat generated by a driving source of the vehicle; and a fluid chamber which is contained in the pressure chamber so as to be expanded and contracted. By the rise in the internal pressure in the pressure chamber as a consequence of evaporation of the pressure medium, the pressure chamber is compressed. The pressurizing fluid is thus supplied from the fluid chamber to the vehicle height adjusting cylinder.
The above-described heat-pressure converting type of pressure source must, like the pressure source to be driven by the engine, be mounted on the vehicle body separately from the damper. Therefore, it is troublesome to mount it on the vehicle body.
In view of the above-described point, the present invention has an object of assembling the pressure source integrally with the damper to thereby improve the ease within which the damper can be mounted on the vehicle body.
SUMMARY OF THE INVENTION
In order to attain the above and other objects, the present invention is a vehicular damper with a vehicle height adjusting function, having a damper main body and a damper rod which is vertically movably inserted into the damper main body, the damper comprising: a cylindrical case which is vertically movably provided on an outside of the damper main body and which is connected to the damper rod; a pressure chamber which is formed between the damper main body and the case and which is filled with a pressure medium which changes its state between a gaseous state and a liquid state; and a heating chamber which heats and evaporates the heating medium inside the pressure chamber by causing a heated heating medium to flow through the heating chamber.
When the heating medium flows through the heating chamber, the pressure medium is heated and evaporated whereby the internal pressure inside the pressure chamber increases. As a result, the case, i.e., the damper rod is pushed by the internal pressure in the pressure chamber to thereby move in the direction of extending relative to the damper main body. This brings about an increased vehicle height. The pressure source which is made up of the pressure chamber and the heating chamber is integrally assembled into the damper and, therefore, the mounting it to the vehicle body becomes easy.
In the above-described arrangement, when the ambient temperature changes, the internal pressure in the pressure chamber changes. As a result, the vehicle height is likely to vary depending on the ambient temperature. As a solution, it is preferable to provide a cover disposed on an outside of the case, the cover being arranged to move up and down depending on the ambient temperature.
When the cover moves up and down relative to the case, the area of the portion which is exposed, out of covering by the cover, to the outside varies, and the amount of heat dissipated from the exposed portion varies. Therefore, by moving the cover such that the area of the exposed portion increases with an increase in the ambient temperature, the increase in the input heat to the pressure chamber as a result of the increase in the ambient temperature is offset by the increase in the amount of heat of dissipation. As a result, there can be obtained a temperature compensation function to restrain the change in the internal pressure of the pressure chamber due to the ambient temperature, i.e., to restrain the change in the vehicle height.
It may also be arranged that the cover is moved up and down by the moving mechanism which is driven by a signal of a temperature sensor which detects the ambient temperature. However, if the cover is supported by a thermally deformable supporting member such as bimetal or the like to move it up and down, the temperature sensor and the moving mechanism become needless. This arrangement is therefore advantageous in seeking for a cost reduction.
Further, if an outer peripheral surface of the case is covered by a thermally insulating material, and a plurality of cooling fins are formed in that part of a vertically elongated outer peripheral surface of the case which is free from covering by the thermally insulating material such that, by the movement of the cover due to an increase in the ambient temperature, the cooling fins are exposed outside, the damper is less likely to be subject to the effect of the ambient temperature. Further, the degree of change in the amount of heat dissipation relative to the moving distance of the cover becomes large. As a result, the stroke of movement of the cover can be minimized. This arrangement is advantageous in seeking for a miniaturization of the damper.
In a damper of the type in which the damper rod is inserted into the damper main body from the upper side, the case, i.e., the damper rod which is connected to the case, is pushed upward relative to the damper main body by the internal pressure of the pressure chamber, resulting in an increases the vehicle height. In this case, if the heating chamber is formed to extend in a vertical direction along a peripheral wall portion of the damper main body such that a vertical overlapping length between the pressure chamber and the heating chamber decreases as a result of an upward movement of the case relative to the damper main body, accompanied by the upward movement of the case, the amount of heat input from the heating chamber to the pressure chamber decreases. As a result, when the vehicle height has reached a predetermined height, the internal pressure in the pressure chamber and the load from the upper side are balanced with each other, and the vehicle height is maintained at that height. In this manner, a levelling function can be obtained without using a special control mechanism. Further, if heating chamber is divided into at least two chambers, and if the heating chamber is arranged to be switchable between a state in which the heating medium flows only into a lower chamber and a state in which the heating medium flows also into an upper chamber, the amount of heat input into the pressure chamber can be varied by the switching. The vehicle height can advantageously be switchable into a plurality of stages.
REFERENCES:
patent: 3067841 (1962-12-01), Kendall
patent: 5601164 (1997-02-01), Ohsaki
patent: 5927071 (1999-07-01), Asanuma et al.
patent: 07308661
Hayakawa Yukio
Nakahara Kiyoshi
Armstrong, Westerman Hattori, McLeland & Naughton
Bartz C. T.
Honda Giken Kogyo Kabushiki Kaisha
Schwartz Christopher P.
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