JPH10318316A - Stay damper having section producing no extensional force - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it so as to have such a section as producing no extensional force near the door closing position of a back door. SOLUTION: A projection 113A provided with sealability is projectingly installed at the oil chamber side (or a piston nut) of a free piston 113, while a piston nut 109 (or the free piston) being equipped with a hollow hole 109A on the inside and installed with a check valve 110 to open merely in a direction exhausting to the outside from the hollow hole 109A will not make pressure in both oil chambers A and B act in the hollow hole 109A by means of the check valve 110 in a fitting section extending a piston rod 101 from a door closing state being fitted in the projection 113A. With this constitution, any extensional force is made so as to be produced there.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stay damper utilizing a gas reaction force having a section where no extension force is generated.

[0002]

2. Description of the Related Art In recent years, most vehicles having a back door BD as shown in FIG. 3 (C) provide a small amount of damping force in the vicinity of the extended end to assist the opening / closing force of the back door BD. Is used. Fig. 3 shows the structure of the stay damper SD.
Explaining in (A), a non-return valve 7 and a piston 8 which are vertically movably guided by a rear projection of the piston 8 are inserted into a lower end spigot portion 1A of the piston rod 1, and a piston nut 9 is provided. Has been concluded. The piston 8 is housed in the cylinder 2 so as to be vertically movable,
The interior of the cylinder is defined by a piston 8 into an upper chamber A and a lower chamber B.

The piston rod 1 is slidably guided by a rod guide 3 fixed to the lower end of a cylinder 2, and seals a lower chamber B with a seal 4. The sealing of the gas and the hydraulic oil 12 into the cylinder is performed via the plug 13, and after the sealing, the mounting member 10 is completely sealed by welding. The stopper 5 is fixed to the cylinder 2 by tightening the outer surface center portion, and restricts the maximum extension of the stay damper by abutting the valve stopper 6 when the piston rod 1 extends. Here, piston rod 1
Is a repulsive force calculated by a product of the cross-sectional area of the piston rod itself and the gas pressure of the upper chamber A, and is constantly urged in the extension direction.

The piston 8 is provided with a piston port 8A for communicating the upper chamber A and the lower chamber B, and a rear seat surface 8B provided below the piston port 8A has
A non-return valve 7 having an orifice 7A for regulating a communication area between the piston upper and lower chambers when the piston rod 1 is extended is seated. When the piston rod 1 contracts, the non-return valve 7 rises from the rear seat surface 8B, and the entire gap between the rear seat surface 8B and the non-return valve 7 has an opening area larger than the piston port 8A. Is the area of the orifice 7A during expansion and the area of the piston port 8A during contraction.

As shown in FIG. 3 (B), if the piston rod 1 is mounted on the vehicle such that the piston rod 1 is at the lower side when the back door is closed, the hydraulic oil 12 stays in the lower chamber B. The piston 8 is gradually immersed in the hydraulic oil 12 so as to cover the orifice 7A, and the hydraulic oil 12 remaining on the lower chamber B side when the back door is closed passes through the orifice 7A from the lower chamber B to the upper part. Move to room A. Such a method of attaching the stay damper to the back door is called a reversing type. Since the passage resistance when the hydraulic oil 12 passes through the orifice 7A is larger than that when the gas passes through the orifice 7A due to the difference in the viscous resistance, the opening speed near the extended end becomes a buffered gentle speed, The impact at the extended end is reduced.

[0006]

The stay damper is shown in FIG.
When shifting from the open position indicated by the phantom line to the closed position indicated by the solid line in FIG.
And the pressure in the gas chambers A and B rises. This pressure is greatest when the piston rod 1 has penetrated the cylinder 2 as far as possible, i.e. in the closed position. In the closed position, the repulsive force of the stay damper obtained by multiplying this pressure by the cross-sectional area of the piston rod 1 is concentrated on the support point of the back door BD. In summer when the temperature is high, the gas pressure rises and the elongation force increases, so when traveling on a rough road in this state, in addition to the above repulsive force, a shock from the road surface is added, and the support point Is severe.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a stay damper having a section in which no extension force is generated in the vicinity of a closing position of a back door BD.

[0007]

To solve the above-mentioned problems, a means adopted by the present invention is to provide a gas chamber having a free piston slidably housed in a cylinder and a high-pressure gas sealed in the cylinder. And an oil chamber filled with hydraulic oil, a piston is slidably housed in the oil chamber, and a piston rod fastened by a piston nut to this piston is made to protrude and retract from the cylinder.
A non-return valve that has a projection provided with a seal on one of the oil chamber side and the piston nut of the free piston and has a hollow inside and is opened only in a direction of discharging from the hollow outside. In the fitting section in which either the mounted piston nut or the free piston extends the piston rod from the closed state in which the protrusion is fitted, the pressure of the oil chamber acts in the hollow hole by the check valve. By doing so, no extension force was generated. "

[0008]

FIG. 1 shows a first embodiment of the present invention. First, the structure will be described. Above the cylinder 102, a free piston 113 fitted with a seal 114 is accommodated, and oil chambers A and B and a gas chamber C in which high-pressure gas is sealed are provided.
And are divided. On the oil chamber side of the free piston 113, a projection 113A having a sealing property is formed so as to protrude by mounting a seal 112 or the like. The upper chamber A and the lower chamber B serving as oil chambers defined below the free piston 113 are filled with hydraulic oil and pressurized by the pressure of the high-pressure gas sealed in the gas chamber C.

The piston 8 is slidably housed in the oil chamber below the free piston 113, and defines the interior of the oil chamber into an upper chamber A and a lower chamber B. The upper end of a piston rod 101 is fastened to the piston 8 by a piston nut 109 and protrudes downward slidably by a rod guide 3 fixed to the lower end of a cylinder 102. A seal is provided between the upper end portion of the piston rod and the threaded surface of the piston nut by applying a seal or applying an adhesive, or the like.

The piston 8 is provided with a piston port 8A for communicating the upper chamber A and the lower chamber B, and a rear seat surface 8B provided below the piston port 8A is provided with a piston rod 101 when the piston rod 101 is extended. A non-return valve 7 having an orifice 7A for regulating a communication area between the piston upper and lower chambers A and B is seated. When the piston 8 slides, the hydraulic oil in the piston upper and lower chambers A and B
It passes through 8A and generates a predetermined damping force.

The inside of the piston nut 109 is a hollow hole 10.
9A, the side facing the free piston 113 is smooth-chamfered, and the projection 1 of the free piston 113 is formed.
13A is easily fitted. Piston nut 109
A groove 109B is provided on the outer surface of the lower end of the hole, and a through hole 109C is opened in the groove from the upper chamber A through the hollow hole 109A.
A rubber band 110 that functions as a check valve that is provided with a tight allowance for the groove 109B and opens only in a direction of discharging from the inside of the hollow hole 109A to the outside is fitted so as to cover the through hole 109C.

In a section in which the hollow hole 109A of the piston nut 109 and the projection 113A of the free piston do not fit, the stay damper SD generates a repulsive force calculated by multiplying the pressure of the upper chamber A by the cross-sectional area of the piston rod 101. , And is always urged in the extension direction to support the weight of the back door BD. When the back door is operated in the closing direction, the piston rod 101 contracts, and in conjunction with this, the free piston 113 also moves upward.

When the outer diameter d of the piston rod 101 and the inner diameter D of the cylinder 102 are set, the moving amount L of the free piston is equal to the moving amount Lp of the piston rod.
It moves up and down in a fixed relationship such that L = Lp · d ² / D ² .
Since there is a difference in the relative movement amount of Lp−L = (1−d ² / D ² ) Lp between the ^two , when the door is closed, the projection 113A of the free piston is inserted into the hollow hole 109 of the piston nut.
A can be designed to fit. The hollow hole 109A of the piston nut corresponds to the projection 113 of the free piston.
When the hydraulic oil is fitted into the hole A, the hydraulic oil in the hollow hole 109A is confined, and the rubber band 110 is pushed open from the through hole 109C and flows out to the upper chamber A.

Immediately before the back door BD is completely closed, the stay damper is fully compressed, and when the stay damper is attached to the back door so as to extend slightly when the door is completely closed, the hollow hole 109A becomes smaller than the minimum volume in the closed state. Although the volume slightly increases, since the through hole 109C is closed by the rubber band 110 acting as a check valve, the inside of the hollow hole 109A has a negative pressure. In this case, if the area inside the hollow hole 109A is set to be the same as the cross-sectional area of the piston rod 101, the upper chamber A will be inside the hollow hole 109A despite being pressurized by the pressure of the gas chamber C. Since no pressure is applied, no extension force is generated. The effect of blocking the pressure to the inside of the hollow hole can be obtained by providing a sealing property on either the projection side or the hollow hole side.
The seal 112 may be attached to the hollow hole side instead of the attachment of the seal 112 to the protrusion side shown in FIG.

When an operating force is applied in the direction of opening the back door to extend the piston rod, the piston nut 109 gradually withdraws from the projection 113A of the free piston.
The negative pressure in the hollow hole 109A gradually increases as it leaves, but the negative pressure is at most -1 atm. Therefore, even with a general stay damper having an outer diameter of the piston rod of 10 mm, the operating force that increases in this section is not increased. The value is less than 1 kgf.
When the hollow hole 109A of the piston nut is separated from the projection 113A of the free piston, the pressure of the upper chamber A is applied to the piston rod 101, and the normal repulsive force is restored.

In this case, the section J in which no extension force is generated is
This is a stroke from when the door is closed to when the hollow hole 109A of the piston nut is separated from the projection 113A of the free piston. Hollow hole 1 of piston nut in closed state
Assuming that the length (fitting length in the design drawing) of the fitting 09A with the projection 113A of the free piston is j, J
= J · D ² / (D ² −d ² ). In a typical stay damper, the outer diameter d of the piston rod is 10 mm and the inner diameter D of the cylinder is 20 mm, J = 1.33j, and the actual fitting length j can be shortened with respect to the required section J. Space saving in the axial direction can be realized.

In this section, if a repulsive force is required to balance the weight of the back door BD, the inner area An of the hollow hole 109A may be smaller than the cross-sectional area Ar of the piston rod 101. Assuming that the repulsive force required when the pressure in the upper chamber is P is f, f = P (Ar-A
n) can be set freely from the relational expression. In a section where the hollow hole 109A of the piston nut 109 projects into the projection 113A of the free piston 113 due to the contraction of the piston rod 101, the hydraulic oil flows through the through hole 109C.
Since a damping force is generated when the vehicle passes through, the door closing speed in this section can be further reduced, so that the impact at the time of closing the door can be reduced.

As is clear from the above description, the repulsive force of the stay damper can be set to zero or an arbitrary magnitude in the closed state of the back door. Since the impact applied to the mounting portion can be reduced, the design around the mounting portion becomes easy.

In the second embodiment of the present invention shown in FIG. 2, the projection 209A is formed to protrude toward the piston nut 209, while the hollow hole 213 is formed.
A is formed on the oil chamber side of the free piston 213. With the contraction of the piston rod 201, the seal 112
When the protrusion 209A of the piston nut having the sealing property is inserted into the hollow hole 213A of the free piston by mounting the oil, the hydraulic oil in the hollow hole 213A of the free piston becomes the oil sump 213B, the communication hole 213C, and the through hole 213D. , The rubber band 210 acting as a check valve is pushed open and flows out to the upper chamber A. The steel ball 213E is used to seal the gap between the gas chamber C and the oil chamber A by driving the free piston 213 after drilling the communication hole 213B, and the purpose can be achieved by welding or screwing a sealing plug. .

As a result, in the closed state, as in the first embodiment, the pressure in the upper chamber A is not applied to the inside of the hollow hole by the check valve.
9A can be prevented from generating an extension force in a section where the free piston 213 fits into the hollow hole 213A.

[0021]

As described above, according to the present invention, the repulsive force of the stay damper can be set to zero or an arbitrary magnitude in the closed state of the back door. Since the impact applied to the mounting portion of the back door can be reduced, the design around the mounting portion becomes easy. In addition, the hollow 109A of the piston nut (in the second embodiment, the protrusion 20
9A) is fitted into the protrusion 113A of the free piston (hollow hole 213A in the second embodiment), and the hydraulic oil flows through the through hole 109C (213 in the second embodiment).
Since a damping force is generated when passing through D), the closing speed of this section can be made even slower, so that the impact at the time of closing the door can be further reduced.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a stay damper according to a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of a stay damper according to a second embodiment of the present invention.

FIG. 3A is a longitudinal sectional view of a stay damper according to the related art. (B) It is explanatory drawing which shows the movement of the hydraulic oil in a stay damper accompanying opening and closing of a back door. (C) It is explanatory drawing of the attachment state to an inversion type back door.

[Explanation of symbols]

 A Oil chamber (upper chamber) B Oil chamber (lower chamber) C Gas chamber SD Stay damper 8 Piston 101, 201 Piston rod 102 Cylinder 109, 209 Piston nut 109A Hollow hole (of piston nut) 110, 210 Check valve (rubber band) 113,213 Free piston 113A Projection (of free piston) 209A Projection (of piston nut) 213A Hollow hole (of free piston)

Claims (2)

[Claims] 1. A free piston is slidably housed in a cylinder, and the cylinder is divided into a gas chamber filled with high-pressure gas and an oil chamber filled with hydraulic oil, and is slidable in the oil chamber. In a stay damper in which a piston is housed and a piston rod fastened by a piston nut to the piston is protruded from the cylinder so as to be able to protrude and retract from the cylinder, a projection having a sealing property is provided on the oil chamber side of the free piston. A piston nut having a hollow inside and a check valve mounted only in the direction of discharging from the hollow to the outside is fitted to extend the piston rod from a closed state in which the free piston is fitted to the projection of the free piston. In the joint section, by not applying the pressure of the oil chamber in the hollow hole by the check valve,
A stay damper characterized in that no extension force is generated. 2. A free piston is slidably housed in a cylinder, and the cylinder is divided into a gas chamber filled with high-pressure gas and an oil chamber filled with hydraulic oil, and is slidable in the oil chamber. A piston rod fastened by a piston nut to the piston and protruding from the cylinder so as to be able to protrude and retract from the cylinder. While a check valve that opens only in the discharge direction is mounted, the piston rod extends from the closed state where the protrusion of the piston nut, which is provided upward and has sealing properties, is fitted in the hollow hole of the free piston. The stay damper is characterized in that in the fitting section to be made, the check valve does not apply the pressure of the oil chamber to the inside of the hollow hole so that no extension force is generated.