JPH0214206B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention makes it possible to obtain desired anti-sag characteristics by increasing the damping force of a device for preventing sagging and sagging during sudden acceleration of a vehicle, particularly a hydraulic shock absorber. It is related to the device.

When a vehicle suddenly accelerates, especially when starting suddenly, a so-called squat phenomenon occurs in which the vehicle body slumps and slumps, resulting in poor ride comfort of the vehicle. It is known that such slumping and slumping are caused by the characteristics of the suspension mechanism of the vehicle.

As is well known, suspensions for vehicles have mechanisms that use hydraulic shock absorbers, and by using this alone or in combination with other springs, suspensions for vehicles have excellent ride comfort and maneuverability. It becomes possible to obtain.

A typical hydraulic shock absorber includes a hydraulic piston interposed between the vehicle body side and the wheel side, and its damping force is always kept constant under certain conditions. That is, the damping force is normally determined by the cross-sectional area of an orifice through which flow flows through two hydraulic chambers separated by a piston, and in conventional devices, the flow cross-sectional area of the orifice is constant. , the damping force under certain conditions was always kept constant.

However, with such a constant damping force,
According to the accumulated results of vehicle running experiments in recent years, it is preferable to change the damping force of the shock absorber according to various conditions, which does not necessarily guarantee the optimal shock absorption effect when the vehicle is actually running. The conclusion has been reached.

In particular, in the conventional shock absorber mechanism mentioned above, its setting is adapted to normal constant speed driving conditions, so when the vehicle suddenly accelerates, its damping force cannot support the large inertia of the vehicle body, and There was a drawback that it caused embedding.

The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to provide a device that can reliably prevent the vehicle from collapsing by increasing the damping force of the shock absorber only when the vehicle is suddenly accelerating. It is in.

In order to achieve the above object, the present invention includes a damping force generating means, a damping force switching means capable of switching the damping force of the damping force generating means, and an actuator that operates the damping force switching means. A detection means for detecting the throttle opening speed of the engine, and a signal for operating the damping force switching means to switch the damping force of the damping force generation means according to the throttle opening speed detected by the detection means is supplied to the actuator. It is characterized by including a control means.

Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

FIG. 1 shows a preferred embodiment of a variable shock absorber device as a damping force generating means suitable for the present invention.

This shock absorber is a conventionally known twin inch tube type shock absorber (for example,
Damping force switching means (solenoid 44), which is a characteristic component of the present invention, has been added to "New Edition Automotive Engineering Handbook" published on November 25, 2015, Volume 7, Chapter 5, Pages 7-65, Figure 5-2). It is composed of

A cylinder 10 of this twin inch tube shock absorber includes an inner cylinder 12 and an outer cylinder 14, and a hydraulic reservoir chamber 100 is formed between the cylinders 12 and 14. A bottom plate 16 is hermetically fixed to the lower end of the outer cylinder 14, and a top plate 18 is similarly hermetically fixed to the upper end. The inner cylinder 12 is housed and held within the outer cylinder 14 by a bottom holder 20 fixed to its lower end and a top holder 22 fixed to its upper end.

A piston 2 is disposed within the inner tube 12 of the cylinder 10.
4 is provided to be slidable in the axial direction, and the inside of the inner cylinder 12 is isolated by a piston 24 into a first hydraulic chamber 102 and a second hydraulic chamber 104.
The piston 24 is fixed to one end of a piston rod 26, the other end of which projects outwardly from the upper end of the cylinder 10. An oil seal 28 is provided between the piston rod 26 and the top plate 18 of the outer cylinder 14.
When the piston rod 26 slides in the axial direction, the hydraulic reservoir chamber 100 and the first hydraulic chamber 10
2 and the pressure oil in the second hydraulic chamber 104 is prevented from leaking.

The piston 24 is provided with an extension-side damping force generating valve 32 that generates an extension-side damping force and a compression-side check valve 31 that is opened during contraction. The fluid passage between the second hydraulic chamber 104 and the hydraulic reservoir chamber 100 is provided with a compression-side damping force generating valve 35 that generates a compression-side damping force and an orifice 33 on the expansion side that opens during expansion. A check valve (no code) is provided.

Therefore, when the piston 24 extends upward relative to the cylinder 10, the oil in the first hydraulic chamber 102 is pressurized and closes the compression side check valve 31. At this time, the oil from the first hydraulic chamber 102 passes through a passage (not shown) formed on the inner circumferential side of the contraction side check valve 31, and further passes through the piston port 30.
The oil then flows through the extension-side damping force generation valve 32 to the second hydraulic chamber 104, and at this time, a damping force during extension is generated according to the degree of opening of the extension-side damping force generation valve 32.

By the way, since the piston rod 26 passes through the first hydraulic chamber 102, when it is extended,
Compared to the increasing volume of the second hydraulic chamber 104, the first
The volume of the hydraulic chamber 102 is reduced by the volume of the piston rod 26 withdrawn from the first hydraulic chamber 102.

Therefore, the extension side check valve (valve with orifice 33) of the bottom holder 20 is moved upward and opened by the oil corresponding to the volume of the withdrawn piston rod 26, thereby causing the hydraulic reservoir chamber 1 to be opened.
Oil from 00 flows from the bottom side of the bottom holder 20 to the moving opening and orifice 3 of the above-mentioned extension side check valve.
3 and flows into the second hydraulic chamber 104. This inflow occurs with almost no resistance.

Here, since the opening area of the extension-side damping force generating valve 32 of the piston 24 changes depending on the rising speed of the piston 24, a damping force characteristic corresponding to the speed of the piston 24 is generated.

Next, when the piston 24 contracts downward relative to the cylinder 10, the oil in the second hydraulic chamber 104 is pressurized. The valve 31 rises, and the oil in the second hydraulic chamber 104 flows into the first hydraulic chamber 102 through a port (no reference numeral) formed outside the piston port 30. Therefore, the pressure in the first hydraulic chamber 102 is also approximately the same as the pressure in the second hydraulic chamber 104.

Here, compared to the volume of the second hydraulic chamber 104 which decreases during contraction as described above, the increased volume of the first hydraulic chamber 102 is smaller by the amount of entry of the piston rod 26.
Therefore, the oil corresponding to the small volume pushes down the compression-side damping force generation valve 35 and flows into the hydraulic reservoir chamber 100 side. This compression-side damping force generation valve 35 generates a damping force during compression.

The structure of the basic hydraulic shock absorber mechanism explained above is the same as the conventional one, but in this embodiment, the shock absorber as the damping force generating means is equipped with a damping force switching means that can switch the damping force. , and an actuator for operating the damping force switching means.

That is, the outer tube 14 of the cylinder 10 has an open tube 14a formed on its side surface, and a plug 38 is airtightly fixed to the open tube 14a.
The plug 38 has a variable orifice 4 as a damping force switching means parallel to the axial direction of the cylinder 10.
0 is set. A hydraulic reservoir chamber 100 is located between one end of the variable orifice 40 and the top holder 22.
A conduit 42 passing through is connected and fixed, and the conduit 42
The end on the top holder 22 side is connected to the first hydraulic chamber 102 via a communication port 22a formed in the top holder 22. Further, the other end of the variable orifice 40 communicates from the hydraulic reservoir chamber 100 to the second hydraulic chamber 104.

The plug 38 is formed with a slot 38a that crosses the variable orifice 40 in a direction perpendicular to the variable orifice 40, and the flow cross-sectional area of the variable orifice 40 is adjusted by changing the amount of blockage of the slot 38a. It becomes possible to do so.

In order to change the amount of blockage of the slot 38a, in this embodiment, an actuator such as a solenoid 44 is incorporated and fixed in the shock absorber. That is, a case 46 of the solenoid 44 is fixed to the plug 38, a core 48 is fixed to the case 46, and a coil 50 is wound and fixed around the core 48. and,
A plunger 52 is slidably housed in the core 48 and the plug 38 along the axis of the solenoid 44, and a valve portion 52a provided at the tip of the plunger 52 is inserted into the slot 38a of the plug 38. The flow cross-sectional area of the variable orifice 40 is adjusted by the sliding position of the valve portion 52a.

In this embodiment, the valve portion 52 of the plunger 52
An open groove 53 is provided on the side surface of a.
When the coil 50 is in the de-energized state, the open groove 53 faces the variable orifice 40, as shown in FIG.
Rebound damping force generation valve 32 provided in 4
Alternatively, the damping force is determined to a predetermined value by the flow cross-sectional area of the compression side damping force generating valve 35 and this variable orifice 40.

Plunger 52 is open (solenoid 50
In the non-excited state), the first hydraulic chamber 102 and the reservoir chamber 100 communicate through the orifice 40, so the hydraulic fluid in the first hydraulic chamber 102, which is pressurized during extension, is attenuated on the extension side as in the known shock absorber. Passing through the force generating valve 32 to the second hydraulic chamber 10
4 (the pressure in the second hydraulic chamber 104 at this time is approximately equal to the pressure in the reservoir chamber 100).

On the other hand, the hydraulic oil in the first hydraulic chamber 102 is
a and the reservoir chamber 10 through the orifice 40.
0, the damping force at this time has a damping force characteristic determined by the opening degree of the extension side damping force generating valve 32 and the opening area of the orifice 40.

Furthermore, during contraction, the pressure in the second hydraulic chamber 104 and the pressure in the first hydraulic chamber 102 are approximately equal, as described above. Therefore, the hydraulic fluid in the second hydraulic chamber 104 passes through the compression damping force generating valve 35 and flows into the reservoir chamber 100.
At the same time, the hydraulic oil in the first hydraulic chamber 102 also flows into the reservoir chamber via the orifice 40. At this time as well, the damping force characteristics are determined by the opening degree of the compression side damping force generating valve 35 and the opening area of the orifice 40.

Then, when an excitation current is supplied to the coil 50 via a lead wire 56 from an excitation circuit, which will be described later, and the plunger 52 is attracted and moved toward the left in FIG. The orifice 40 is thus closed and the flow of oil through the orifice 40 is stopped. In this state, the shock absorber has a flow cross-sectional area determined by the extension side damping force generating valve 32 or the contraction side damping force generating valve 35, and the damping force is adjusted.
That is, when the orifice 40 is closed, the operation is similar to that of a normal twin tube type shock absorber without a damping force switching means.

When the plunger 52 is closed, higher damping force characteristics can be obtained than when the plunger 52 is open. From this, the damping force characteristics can be controlled by controlling the excitation of the coil.

Therefore, if the solenoid coil 50 is energized only when the vehicle is rapidly accelerating, causing the phenomenon of sagging, the desired sagging prevention effect can be achieved.

FIG. 2 shows a preferred embodiment of the detection means for detecting the throttle opening speed of the engine and the control means thereof.

The throttle sensor 60 is composed of a well-known potentiometer for electrically detecting the throttle opening, and by rotating the slider 64 of the potentiometer in accordance with the throttle opening, the throttle sensor 60 detects the next stage of differentiation. The throttle opening can be supplied to the circuit 73 and the control circuit 62 as a voltage signal.

Note that the throttle opening may be an accelerator opening.

The differential circuit 73 and the control circuit 62 detect sudden acceleration of the vehicle from the throttle opening signal from the throttle sensor 60. For this reason, in the embodiment, the throttle opening signal is detected by the throttle opening signal. Sudden acceleration is detected because the speed is higher than normal driving conditions.

In this case, the sudden opening of the throttle is detected by a differential circuit 73 consisting of an operational amplifier 66, resistors 68, 70, and a capacitor 72, and this differential circuit 73 and the throttle sensor 60 detect the throttle opening speed of the engine. It constitutes a detection means for detecting.

The opening speed switching circuit 75 at the next stage is controlled by the differential output at this time, that is, the output when the throttle opening speed is equal to or higher than a predetermined value. That is, the opening speed switching circuit 75 is composed of a transistor 74 and resistors 76, 78, and 79. When the throttle opening speed is above a predetermined value, the transistor 74 is turned on, and the output is sent to an AND gate 80.
supply to

A hysteresis circuit 81 is connected to the opening speed switching circuit 75, and the hunting phenomenon is prevented by changing the on/off level of the hysteresis circuit 81. The hysteresis circuit 81 is made up of a transistor 82 and resistors 84, 86, and 87, and a desired hysteresis characteristic is provided by changing the base bias voltage of the opening speed switching circuit 75.

On the other hand, in order to detect the throttle opening at a predetermined value, in this embodiment a larger opening than during steady running, the opening signal of the throttle sensor 60 is generated by an operational amplifier 88 and resistors 90, 92, 94, and 96. It is supplied to a comparator circuit 97, and the resistor 9
The throttle opening signal is compared with a predetermined comparison voltage determined at 2 and 94, and when the comparison voltage exceeds a predetermined value, a signal is output to the AND gate 80.

The output of AND gate 80 is flip-flop 9
When both of the above conditions are satisfied and rapid acceleration of the vehicle is detected, the flip-flop 98 has a Q output of "1" and supplies an excitation current to the solenoid coil 50 described above.

The output of the amplifier 88 forming the comparator 97 is supplied to the reset input of the flip-flop 98 via an inverter 300, and the flip-flop 98 is reset when the throttle opening falls below a predetermined value.

The output of the flip-flop 98 supplies an excitation current to the coil 50 via the coil excitation circuit 101.
In the embodiment, this excitation circuit 101 includes transistors 302 and 304 connected in series, a resistor 106,
108 and a diode 110 for absorbing back electromotive force
The transistors 302 and 304 are turned on by the Q output of the flip-flop 98, and supply excitation current to the solenoid coil 50 for a predetermined period of time.

The operation of FIG. 2 will be explained in detail below based on the time chart of FIG. 3.

The opening degree of the output 201 of the throttle sensor 60 increases from the time of starting at time t1 to t4, and from t4 to t6, the throttle opening degree is maintained larger than that in the normal driving state during acceleration, and from time t6, this opening degree increases. It gradually decreases until t8.

Then, the differentiation circuit 73 differentiates this opening degree signal 201 and the differential value is sent to the opening degree switching circuit 75.
The bias setting value of the transistor 74 at , that is, the setting value v1 determined by the resistors 78 and 86
At time t2 exceeding the opening degree switching circuit 7
5 outputs a signal 203 to an AND gate 80.

Note that when the differential signal 202 of the differential circuit 73 exceeds the predetermined ON operation setting value v1 and the transistor 74 is turned on, the transistor 82 of the hysteresis circuit 81 is also turned on at the same time, and as a result, the bias of the opening degree switching circuit 75 is changed. Change the value and change its off-actuation level to the on-actuation level
Change to v2 which is smaller than v1. Therefore, the opening switching circuit 75 maintains its ON state until the differential output 202 becomes smaller than the changed OFF operation level v2, thereby reliably preventing hunting, and in the embodiment, at time t5. The opening degree switching circuit 73 is turned off.

On the other hand, the throttle opening signal 201 is compared with a reference value in a comparator, and at time t3 when the throttle opening exceeds the desired set angle θ, the comparator 9
7 outputs a comparison output 204 which becomes "1", and as a result, the AND gate 80 outputs a signal 205 at the "1" level and sets the flip-flop 98.

Therefore, a Q output of "1" is supplied from flip-flop 98 to solenoid drive circuit 101, transistors 102 and 104 are turned on at time t3, and a predetermined excitation current is supplied to solenoid coil 50.

As a result of the above, the variable orifice 40 of the shock absorber mechanism has a small flow cross-sectional area and is closed in the embodiment, and the damping force of the shock absorber becomes significantly larger than that during normal running, and the damping force is significantly increased when the vehicle suddenly accelerates. It is possible to reliably prevent sagging.

As described above, at time t5, the throttle opening is stabilized, so the opening switching circuit 75 is turned off and the AND gate 80 is closed, but the flip-flop 98 maintains its set state and the solenoid coil 50 remains energized. is retained.

Then, at time t7 when the desired rapid acceleration is completed and the throttle opening becomes small, the output 2 of the comparator 97 is
04 becomes "0", and as a result, the flip-flop 98 is reset and the solenoid coil 50 is de-energized. Therefore, at time t7, the variable orifice 40 becomes open again, and the damping force of the shock absorber returns to the normal running state.

As explained above, according to the present invention, the damping force of the shock absorber is increased only during specific sudden accelerations such as when starting suddenly, and the damping force of the shock absorber is reliably prevented from sagging, improving the ride comfort of the vehicle and improving the control of the vehicle. It becomes possible to significantly improve stability, and during normal running, it becomes possible to restore the damping force of the shock absorber to the normal state and create a stable running condition.

In this embodiment, a case has been described in which the damping force of the shock absorber is controlled by detecting a sudden acceleration state based on the throttle opening speed and throttle opening degree as a preferred example, but the present invention detects the throttle opening speed at the minimum. The sudden acceleration state can be detected by using the throttle opening speed detection means alone, or in combination with other running state detection means such as the throttle opening speed and throttle opening as in this embodiment. It may also be detected by

In the present invention, the shock absorber mechanism whose damping force is controlled may be provided on all four wheels, or it may be provided only on the rear wheel, which has a large effect on the clinging phenomenon, and the number of these installed may be adjusted. Correspondingly, it is preferable to provide an arbitrary number of control circuits 62.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a shock absorber mechanism suitable for the sagging prevention device according to the present invention, and FIG. 2 is a circuit showing a throttle sensor, a differential circuit, and a control circuit suitable for the present invention. 3 is a time chart of FIG. 2. 10... Cylinder, 12... Inner cylinder, 14... Outer cylinder, 24... Piston, 40... Variable orifice, 44... Solenoid, 50... Coil, 52
... Plunger, 60 ... Throttle sensor, 6
2...Control circuit, 73...Differential circuit.

Claims (1)

[Claims] 1. A damping force generation means, a damping force switching means capable of switching the damping force of the damping force generation means, an actuator that operates the damping force switching means, and a detection means that substantially detects the throttle opening speed of the engine. and control means for supplying a signal to the actuator to operate the damping force switching means to switch the damping force of the damping force generating means in accordance with the throttle opening speed detected by the detection means. A device that prevents the vehicle from becoming trapped during sudden acceleration.