JP7632336B2 - Actuator - Google Patents

Description

The present invention relates to an actuator that generates operating gas from combustion gas when activated, and is suitable for use in automobile safety devices mounted on vehicles, such as a hood lift-up device that lifts the vehicle's hood panel when catching a pedestrian.

Conventional actuators of this type include those used in hood lift-up devices that lift hood panels, and are configured as piston cylinder types that use combustion gas generated by igniting a gas generator when it is activated as the actuating gas (see, for example, Patent Document 1). In this actuator, the piston rod is configured to include a piston portion that can slide within the cylinder, and a rod portion that extends from the piston portion and protrudes outside the cylinder, and moves the vehicle's hood panel, which serves as a support material for receiving pedestrians, upward to a position where the pedestrian can be supported. When this actuator is activated, the piston rod moves the piston portion forward within the cylinder to the forward movement completion position, while the tip of the rod portion abuts against the hood panel, and lifts the hood panel.

JP 2014-133535 A

However, in conventional actuators, if the force of the hood panel's upward movement (in other words, the pushing force of the piston rod moving forward) is large, the area of the hood panel that the tip of the rod portion of the piston rod comes into contact with can be damaged, and this requires adjustments such as providing a reinforcing material at the area where the tip of the rod portion comes into contact, which increases the weight of the hood panel and is difficult to deal with simply.

The present invention aims to solve the above-mentioned problems and provide an actuator that allows easy adjustment of the pressing force of the piston rod during operation.

The actuator according to the present invention is an actuator configured such that a piston portion of a piston rod in a cylinder moves toward a ceiling portion of the cylinder by working gas consisting of combustion gas generated upon activation of a gas generator arranged at the bottom of the cylinder, and a rod portion of the piston rod extending so as to penetrate the ceiling portion is moved forward to move a pressed portion against which a tip end of the rod portion abuts,
the cylinder includes a throttle portion between the piston portion and the gas generator before activation, the throttle portion having a gas passage hole having an opening diameter smaller than an opening diameter of an inner circumferential surface of the piston portion that slides, through which the working gas passes,
The piston portion is
A main body portion that slides on the inner circumferential surface of the cylinder during operation;
a fitting portion that protrudes from the main body portion toward a bottom side of the cylinder and is fitted and inserted into the gas insertion hole so as to be removable from the gas insertion hole of the throttle portion when the working gas is discharged from the gas generator;
The present invention is characterized in that it is configured to include the following.

In the actuator according to the present invention, when the gas generator discharges the working gas during operation, the working gas presses the fitting portion as it tries to pass through the gas passage hole of the throttle portion, causing the fitting portion to leave the gas passage hole, and the working gas that has passed through the gas passage hole presses the piston portion including the fitting portion and the main body portion. At that time, the fitting portion pressed by the working gas at the beginning of operation is pressed by the pressure of the working gas according to the opening area of the gas passage hole into which it is inserted, and after the fitting portion leaves the gas passage hole, the piston portion including the fitting portion and the main body portion is pressed by the pressure of the working gas according to the opening area on the inner circumferential surface side of the cylinder in which the main body portion slides, causing the piston rod to move forward. That is, the pressing force (pressing load) of the piston rod at the beginning of operation is the value obtained by multiplying the opening area of the gas insertion hole by the pressure of the working gas, and is smaller than the value obtained by multiplying the opening area of the inner circumferential surface of the cylinder on which the entire piston part slides by the pressure of the working gas. Therefore, since the pressing load of the piston rod at the beginning of operation is small, the pressing load when the piston rod abuts the tip of the rod part against the pressed part after the fitting part leaves the gas insertion hole can be suppressed to a smaller value than when the pressure of the working gas acts on the opening area of the inner circumferential surface of the cylinder on which the entire piston part slides from the beginning of operation. In addition, even if the length of the gas insertion hole is long, it is possible to maintain the state of a small pressing load at the beginning of operation until the fitting part leaves the gas insertion hole significantly, compared to when the gas insertion hole is short, and the pressing load when the piston rod abuts the tip of the rod part against the pressed part thereafter can also be suppressed to a small value.

Therefore, in the actuator of the present invention, the pressure of the piston rod during operation can be easily adjusted simply by adjusting the opening area and length of the gas insertion hole into which the insertion portion is inserted.

In the actuator according to the present invention, the gas insertion hole of the throttle portion has a cylindrical inner circumferential surface along an axial direction of the gas insertion hole,
The fitting portion may be configured to include a sliding portion that is slidable on an inner circumferential surface of the gas insertion hole.

In this configuration, when the actuator is first activated, the sliding part of the insertion part slides a certain distance on the inner circumferential surface of the gas insertion hole, and the low pressing force (pressing load) of the piston rod at the beginning of activation can be maintained for a long period of time for that sliding distance, and the pressing force when the piston rod subsequently abuts the tip of the rod part against the pressed part can also be kept small.

In the actuator according to the present invention, the insertion portion may be configured to include an outer peripheral edge portion that abuts against the entire periphery of the ceiling side of the cylinder at the gas insertion hole, and an insertion portion that is inserted into the gas insertion hole with an outer diameter that gradually narrows from the outer peripheral edge portion.

In this configuration, when the fitting portion is released from the gas hole at the beginning of actuator operation, the outer peripheral edge of the fitting portion can quickly move away from the periphery of the gas hole, and the working gas that has passed through the gas hole can flow to the bottom side of the main body of the piston portion of the piston rod. In other words, the state of low pressing load on the piston rod due to the pressure of the working gas acting on the fitting portion at the beginning of actuator operation lasts for a short period of time, and the suppression of the pressing force when the tip of the rod portion of the piston rod is brought into contact with the pressed portion can be adjusted to be smaller.

The actuator according to the present invention may be used in a hood lift-up device in which the tip of the rod portion abuts against a rear side portion of a vehicle hood panel, which serves as a pressure receiving portion, to lift up the hood panel.

1 is an explanatory diagram showing a state before operation of a hood lift-up device in which an actuator according to an embodiment of the present invention is used; 1 is an explanatory diagram showing a state in which a hood lift-up device using an actuator according to an embodiment is in operation; FIG. 5A to 5C are schematic cross-sectional views of the actuator of the embodiment before and after actuation. FIG. 4 is a schematic enlarged cross-sectional view illustrating an initial stage of operation of the actuator of the embodiment. FIG. 11 is a schematic enlarged cross-sectional view illustrating an early stage of operation of a modified example of the actuator of the embodiment. FIG. 11 is a schematic enlarged cross-sectional view illustrating an initial stage of operation of another modified example of the actuator of the embodiment.

One embodiment of the present invention will be described below with reference to the drawings. As shown in Figures 1 to 3, the actuator 20 of this embodiment is used in a hood lift-up device U as a safety device for an automobile, and is disposed near the front side of the hinge mechanism 9 below the rear end 7c of the hood panel 7 of the vehicle V.

In this embodiment, a sensor capable of detecting or predicting a collision with a pedestrian is disposed on the front bumper (not shown) of the vehicle V, and when a control circuit (not shown) that receives a signal from the sensor detects a collision between the vehicle V and a pedestrian based on the signal from the sensor, the control circuit ignites a gunpowder (not shown) in a gas generator 38 (described later) of the actuator 20, and uses the resulting combustion gas as the operating gas G to extend the actuator 20 and operate the flip-up device U.

As shown in FIG. 1, the hood panel 7 covers the upper part of the engine room ER of the vehicle V, and is connected to the vehicle body 1 of the vehicle V by a hinge mechanism 9 arranged near the rear end 7c on both left and right edges of the vehicle V so that it can be opened and closed in a front-opening manner. The hood panel 7 is made of sheet metal made of aluminum alloy or the like, and is composed of an outer panel 7a on the upper surface side and an inner panel 7b located on the lower surface side and having improved strength than the outer panel 7a. The hood panel 7 is configured to be plastically deformable so that it can absorb the kinetic energy of a pedestrian when it receives it. In the embodiment, when the vehicle V collides with a pedestrian, the actuator 20 is activated, and as shown in FIG. 2, a deformation space D can be formed between the rear end 7c of the raised hood panel 7 and the engine room ER, so that the amount of plastic deformation during bending plastic deformation can be increased, and the hood panel 7 can absorb a large amount of the pedestrian's kinetic energy.

The hinge mechanism 9 is configured to include a hinge base 10 that is fixed to the mounting flange 2a on the body 1 side below the rear end 7c of the hood panel 7, and a hinge arm 12 that is supported by the hinge base 10 using a support shaft 11 and is connected to the underside of the rear end 7c of the hood panel 7. The mounting flange 2a is connected to the hood ridge reinforcement 2 on the body 1 side. The hinge mechanism 9 is configured to open around the support shaft 11 on the base end 12a side of the hinge arm 12 when the hood panel 7 is opened during normal use (see the two-dot chain line in Figure 1).

The hinge arm 12 has a tip-side mounting portion 12d that extends forward from the base end 12a and is fixed to the inner panel 7b. The mounting portion 12d has a contact portion 12e that receives the tip portion 53 (described later) on its underside when the actuator 20 is activated. Furthermore, the hinge arm 12 has a notch 12f near the mounting portion 12d to facilitate plastic deformation. When the rising tip portion 53 of the actuator 20 during activation contacts the contact portion 12e, the plastic deformation portion 12g near the notch 12f is plastically deformed, and together with the contact portion 12e and the mounting portion 12d, the rear end 7c of the hood panel 7 is raised to provide a deformation space D.

As shown in Figures 1 to 4, the actuator 20 is a piston cylinder type actuator, and is configured with a cylinder 22 having a gas generator 38 at its bottom 36, and a piston rod 40. The actuator 20 is held by a mounting bracket 18 fixed to the body 1 side of the vehicle V, and is disposed below the rear end 7c of the hood panel 7, specifically, below the abutment portion 12e.

The gas generator 38 uses a squib or micro gas generator that generates combustion gas to be used as the working gas G by igniting a specified explosive (not shown) when it is activated, and by burning the explosive itself or by burning a gas generating agent that is ignited by the explosive, and a connector 38b is provided on the base side exposed from the bottom 36 away from the tip 38a that discharges the working gas G, to connect a lead wire (not shown) that inputs an ignition electric signal from a specified control circuit. When the gas generator 38 inputs an ignition electric signal from a control circuit (not shown), it ignites and burns the built-in explosive, and if necessary, also burns the gas generating agent to generate combustion gas, which is discharged from the tip 38a as the working gas G and supplied to the piston part 41 side.

The cylinder 22 is configured such that a gas generator 38 is disposed on the bottom 36 side, a ceiling 23 on the tip (upper end) side away from the bottom 36 is provided with an insertion hole 24 through which a rod portion 52 of a piston rod 40 described later is inserted, and a peripheral wall portion 26 having an inner peripheral surface 26a through which the piston portion 41 of the piston rod 40 slides is provided between the bottom 36 and the ceiling 23. The cylinder 22 is formed by pressing a metal pipe such as a steel pipe, and a block material 25 made of a steel material or the like with an insertion hole 24 on the ceiling 23 side is fixed by crimping, and a gas generator 38 is disposed on the bottom 36 side, and the edge 36a is crimped to fix the gas generator 38.

The cylinder 22 has a tapered throttle section 28 formed immediately above the gas generator 38 between the body section 42 of the piston section 41 and the gas generator 38 before operation, to narrow the inner diameter. The throttle section 28 has a gas insertion hole 29 with an opening diameter d1 smaller than the opening diameter d2 of the inner circumferential surface 26a of the peripheral wall section 26. The inner circumferential surface 26a of the peripheral wall section 26 and the inner circumferential surface 29a of the gas insertion hole 29 are configured as circular openings.

The piston rod 40 is made of a steel material or the like and is configured to include a piston portion 41 disposed within the cylinder 22, and a rod portion 52 extending from the piston portion 41 and protruding through an insertion hole 24 in the ceiling portion 23 of the cylinder 22. The tip portion 53 of the rod portion 52 is formed by screwing a block material 54 made of steel or the like to the tip portion 52a of the rod portion 52.

The piston portion 41 is configured to include a cylindrical main body portion 42 that slides on the inner circumferential surface 26a of the peripheral wall portion 26 of the cylinder 22 during operation, and an insertion portion 46 that protrudes from the main body portion 42 toward the bottom portion 36 of the cylinder 22 and is fitted into the gas insertion hole 29 of the throttling portion 28 so as to be removable from the gas insertion hole 29 when the gas generator 38 discharges the operating gas G.

In this embodiment, the gas passage hole 29 of the constriction portion 28 is configured with a cylindrical inner peripheral surface 29a that is aligned with the axial direction XD of the gas passage hole 29, and the fitting portion 46 is configured with a cylindrical sliding portion 47 that can slide on the inner peripheral surface 29a of the gas passage hole 29.

The piston portion 41 has grooves 43, 48 on the outer circumferential surfaces 42a, 46a of the main body portion 42 and the sliding portion 47 of the insertion portion 46 to improve gas sealing, and sealing materials 44, 49 made of rubber or the like are provided.

In the actuator 20 of this embodiment, the lead wire from the control circuit (not shown) is connected to the connector 38b of the gas generator 38, and the cylinder 22 is attached and fixed to a portion of the vehicle V below the rear end 7c of the hood panel 7 using the mounting bracket 18, allowing the flip-up device U to be mounted on the vehicle V to which the hinge mechanism 9 has already been attached.

After the lift-up device U is mounted on the vehicle V, the actuator 20 operates, causing the gas generator 38 to generate the working gas G, and the pushing force of the working gas G causes the rod portion 52 of the piston rod 40 of the actuator 20 to protrude from the cylinder 22 as shown in Figs. 1 and 2, and the tip portion 53 at the upper end of the rod portion 52 abuts against the abutment portion 12e, pushing up the abutment portion 12e together with the rear end 7c of the hood panel 7. As a result, the rear end 7c side of the hood panel 7 is pushed up, ensuring a wide deformation space D, and the increased amount of plastic deformation allows the pedestrian to be accommodated with the impact mitigated.

In the actuator 20 of the embodiment, when the gas generator 38 discharges the working gas G during operation, as shown in Figures 4A and 4B, the working gas G attempts to pass through the gas insertion hole 29 of the throttling portion 28, pressing against the fitting portion 46 and causing the fitting portion 46 to separate from the gas insertion hole 29. Then, the working gas G that has passed through the gas insertion hole 29 presses against the piston portion 41, including the fitting portion 46 and the main body portion 42. At that time, the fitting portion 46, which is pressed by the working gas G at the beginning of operation, is pressed by the pressure of the working gas G according to the opening area S1 of the gas insertion hole 29 into which it is fitted, and after the fitting portion 46 leaves the gas insertion hole 29, the piston portion 41, which is the combination of the fitting portion 46 and the main body portion 42, is pressed by the pressure of the working gas G according to the opening area S2 on the inner surface 26a side of the cylinder 22 against which the main body portion 42 slides, and the piston rod 40 moves forward.

That is, the pressing force (pressing load) F1 of the piston rod 40 at the beginning of operation is a value (F1=S1×P) obtained by multiplying the opening area S1 of the gas insertion hole 29 by the pressure P of the working gas G, and is smaller than a value (F2=S2×P) obtained by multiplying the opening area S2 of the inner circumferential surface 26a of the cylinder 22, on which the entire piston portion 41 slides, by the pressure of the working gas G. In other words,
S2>S1,
The initial pressure load F1 = S1 x P is:
F2 is smaller than the value of S2×P (F1<F2).

Therefore, since the pressing load F1 of the piston rod 40 at the beginning of operation is small, the pressing load FX (see FIG. 2) when the piston rod 40 abuts the tip 53 of the rod portion 52 against the abutment portion 12e as the pressed portion after the fitting portion 46 leaves the gas insertion hole 29 can be suppressed to be smaller than when the pressure P of the working gas G acts on the opening area S2 of the inner circumferential surface 26a of the cylinder 22 on which the entire piston portion 41 slides from the beginning of operation. Also, even if the length dimension L (see FIG. 4) of the gas insertion hole 29 is increased, the state of the small pressing load F1 at the beginning of operation can be maintained for a long time until the fitting portion 46 leaves the gas insertion hole 29, compared to when the gas insertion hole 29 is made short, and the pressing load FX when the piston rod 40 abuts the tip 53 of the rod portion 52 against the abutment portion 12e as the pressed portion can also be suppressed to be small.

Therefore, in the actuator 20 of this embodiment, the pressing force FX of the piston rod 40 during operation can be easily adjusted simply by adjusting the opening area S1 and length dimension L of the gas insertion hole 29 into which the insertion portion 46 is inserted.

In the actuator 20 of this embodiment, the gas passage hole 29 of the restrictor portion 28 has a cylindrical inner peripheral surface 29a that is aligned with the axial direction XD of the gas passage hole 29, and the fitting portion 46 has a sliding portion 47 that can slide on the inner peripheral surface 29a of the gas passage hole 29.

Therefore, in the embodiment, when the actuator 20 is initially operated, the sliding portion 47 of the insertion portion 46 slides a certain distance on the inner circumferential surface 29a of the gas insertion hole 29, and the initial low pressing force (pressing load) F1 of the piston rod 40 can be maintained for a long period of time for the sliding distance SL (see FIG. 4), and the pressing force FX when the piston rod 40 subsequently abuts the tip portion 53 of the rod portion 52 against the abutment portion 12e as the pressed portion can also be kept small.

In addition to being cylindrical, the insertion portion may also be a mushroom-shaped puppet valve-type insertion portion 66, as in the actuator 20A shown in FIG. 5.

In this actuator 20A, the insertion portion 66 of the piston rod 40A is conically shaped and includes an outer peripheral edge portion 67 that abuts against the entire circumference of the periphery 31 on the ceiling side of the cylinder 22A at the gas insertion hole 29A provided in the throttling portion 28A, and an insertion portion 68 that is inserted into the gas insertion hole 29A with the outer diameter gradually narrowing from the outer peripheral edge portion 67.

In the actuator 20A having such a configuration, when the fitting portion 66 is released from the gas through hole 29A at the beginning of operation, the outer peripheral edge portion 67 of the fitting portion 66 can quickly separate from the periphery 31 of the gas through hole 29A, and the working gas G that has passed through the gas through hole 29A can flow to the bottom surface 42b side of the body portion 42 of the piston portion 41 in the piston rod 40A. In other words, the state of the low pressing load F1 (opening area S1 of the gas through hole 29A x pressure P of the working gas G) of the piston rod 40A due to the pressure P of the working gas G acting on the fitting portion 66 at the beginning of operation of the actuator 20A becomes short, and the suppression of the pressing force FX when the tip portion 53 of the rod portion 52 in the piston rod 40A is brought into contact with the contact portion 12e as the pressed portion can be adjusted to be smaller (see FIG. 2).

Although the configuration of the actuator 20A near the fitting portion 66 and the gas insertion hole 29A is different from that of the actuator 20, the ceiling portion 23 side of the cylinder 22A and the main body portion 42 of the piston portion 41 of the piston rod 40A, etc., are configured in the same manner as the actuator 20.

The insertion portion may also be a spherical insertion portion 66B, as in the actuator 20B shown in Figure 6.

In this actuator 20B, the insertion portion 66B of the piston rod 40B is spherical and includes an outer peripheral edge portion 67B that abuts against the entire circumference of the periphery 31B on the ceiling side of the cylinder 22B at the gas insertion hole 29B provided in the throttle portion 28B, and an insertion portion 68B that is inserted into the gas insertion hole 29B with an outer diameter that gradually narrows from the outer peripheral edge portion 67B. A chamfered abutment seat 33 against which the outer peripheral edge portion 67B abuts is formed at the portion of the periphery 31B that abuts against the outer peripheral edge portion 67B.

In the actuator 20B having such a configuration, when the fitting portion 66B is released from the gas through hole 29B at the beginning of operation, the outer peripheral edge portion 67B of the fitting portion 66B can quickly separate from the periphery 31B of the gas through hole 29B, and the working gas G that has passed through the gas through hole 29B can flow to the bottom surface 42b side of the body portion 42 of the piston portion 41 in the piston rod 40B. In other words, the state of the low pressing load F1 (opening area S1 of the gas through hole 29B x pressure P of the working gas G) of the piston rod 40B due to the pressure P of the working gas G acting on the fitting portion 66B at the beginning of operation of the actuator 20B becomes short, and the suppression of the pressing force FX when the tip portion 53 of the rod portion 52 in the piston rod 40B is brought into contact with the contact portion 12e as the pressed portion can be adjusted to be smaller (see FIG. 2).

In this actuator 20B, the configuration of the insertion portion 66B and the gas insertion hole 29B are different from those of the actuator 20, but the ceiling portion 23 side of the cylinder 22B and the main body portion 42 of the piston portion 41 of the piston rod 40B, etc., are configured in the same way as the actuator 20.

In addition, the actuators 20, 20A, and 20B in the embodiments are shown as being used in a lifting device U that lifts up the hood panel 7, but as long as the gas generator is activated to move the piston rod forward at a predetermined time, the actuators can be used in a variety of automobile safety devices without being limited to the embodiments.

7...hood panel, 20, 20A, 20B...actuator, 22, 22A, 22B...cylinder, 23...ceiling portion, 26...peripheral wall portion, 26a...(sliding portion) inner peripheral surface, 28, 28A, 28B...throttling portion, 29, 29A, 29B...gas insertion hole, 29a...inner peripheral surface, 31, 31B...(ceiling side) periphery, 36...bottom portion, 38...gas generator, 40, 40A, 40B...piston rod, 41...piston portion, 42...main body portion, 46...insertion portion, 47...sliding portion, 52...rod portion, 53...tip portion, 66, 66B...insertion portion, 67, 67B...outer peripheral edge portion, 68, 68B...insertion portion,
d0...(cylinder) opening diameter, d1...(gas hole) opening diameter, G...(operating gas), U...(automobile safety device) hood lift-up device.

Claims (3)

An actuator configured such that a piston portion of a piston rod in the cylinder moves toward a ceiling portion of the cylinder by working gas consisting of combustion gas generated upon activation of a gas generator disposed at a bottom of the cylinder, and a rod portion of the piston rod extending so as to penetrate the ceiling portion is moved forward to move a pressed portion against which a tip end of the rod portion abuts,
the cylinder includes a throttle portion between the piston portion and the gas generator before activation, the throttle portion having a gas passage hole having an opening diameter smaller than an opening diameter of an inner circumferential surface of the piston portion that slides, through which the working gas passes,
The piston portion is
A main body portion that slides on the inner circumferential surface of the cylinder during operation;
a fitting portion that protrudes from the main body portion toward a bottom side of the cylinder and is fitted and inserted into the gas insertion hole so as to be removable from the gas insertion hole of the throttle portion when the working gas is discharged from the gas generator;
The present invention is configured with
The narrowing portion is
a fitting portion into which the fitting portion of the piston portion before actuation fits;
a tapered portion disposed on the gas generator side with respect to the fitting portion, the tapered portion having an opening diameter gradually narrowing from the bottom side toward the ceiling side;
having
The actuator , wherein the gas generator is disposed in contact with the tapered portion . the gas insertion hole of the throttle portion has a cylindrical inner circumferential surface along an axial direction of the gas insertion hole,
2. The actuator according to claim 1, wherein the fitting portion is provided with a sliding portion that is slidable against an inner circumferential surface of the gas insertion hole. 3. The actuator according to claim 1 or 2, characterized in that the tip of the rod portion is used in a hood lifting device configured to abut against a rear side portion of a hood panel of a vehicle as a pressed portion, thereby lifting up the hood panel.

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