JP2022041760A - Stabilizer system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the practicality of a stabilizer system. SOLUTION: (a) Stabilizer bars 16 and 60 and (b) are interposed between the stabilizer bar and a vehicle body 24 or a wheel holding member 18, and the volume is internally increased as the wheel holding member moves up and down. By switching between the hydraulic cylinders 26 and 72 in which the two fluctuating liquid chambers 26c and 72c are partitioned, and (c) prohibition and permissible of the inflow and outflow of the hydraulic fluid into those two liquid chambers, the stabilizer bar of the vehicle body In a stabilizer system equipped with stabilizer devices 12'and 14' having switching mechanisms 42'and 80'to switch between enabling and disabling the roll suppressing effect, two in a state where the roll suppressing effect is enabled. Low-pressure chamber hydraulic pressure drop preventing means 94, 96 for preventing the pressure drop of the hydraulic fluid in the liquid chamber, whichever is lower, are provided. Cavitation phenomenon in the cylinder can be prevented. [Selection diagram] Fig. 7

Description

The present invention relates to a stabilizer system mounted on a vehicle.

The stabilizer system includes a stabilizer device having a stabilizer bar as a main component. For example, in the stabilizer system described in the following patent document, the stabilizer device is configured to include a hydraulic rotary actuator or a hydraulic cylinder and is switched. By controlling the operation of the electromagnetic on-off valve as a mechanism by the controller, the effect of suppressing the roll of the vehicle body by the stabilizer bar is controlled.

Japanese Unexamined Patent Publication No. 2004-136814

In the stabilizer system described in the above patent document, the hydraulic rotary actuator or the hydraulic cylinder is a liquid in which the pressure of the hydraulic fluid becomes a negative pressure (pressure lower than the atmospheric pressure) when the roll suppression effect is enabled. There is a room. In such a liquid chamber, for example, a cavitation phenomenon (a phenomenon in which bubbles are generated in the liquid chamber and the bubbles burst) occurs, and the cavitation phenomenon contributes to the generation of abnormal noise in the system. Therefore, by suppressing the cavitation phenomenon, the practicality of the stabilizer system can be improved. The present invention has been made in view of such circumstances, and an object of the present invention is to provide a highly practical stabilizer system.

In order to solve the above problems, the stabilizer system of the present invention mounted on the vehicle is
(a) Stabilizer bar supported by the vehicle body and connected to a wheel holding member that holds the wheels rotatably and is allowed to move up and down with respect to the vehicle body, and (b) the stabilizer bar and the vehicle body or the wheel holding member. A hydraulic cylinder in which two liquid chambers whose volumes change with the vertical movement of the wheel holding member are partitioned between the two liquid chambers, and (c) the two liquids of the hydraulic cylinder. A stabilizer device having a switching mechanism for switching between enabling and disabling the roll suppressing effect of the vehicle body by the stabilizer bar by switching between prohibition and permissible of the inflow and outflow of the hydraulic fluid into the chamber.
It is equipped with a controller that controls the switching mechanism of the stabilizer device.
The stabilizer system further
In a state where the roll suppressing effect of the stabilizer device is enabled, the pressure of the hydraulic fluid of the two liquid chambers of the hydraulic cylinder, whichever is lower, is reduced in the low pressure chamber to prevent the pressure from decreasing. It is characterized by being equipped with preventive measures.

According to the stabilizer system of the present invention, by providing the low pressure chamber hydraulic pressure drop preventing means, the pressure of the hydraulic fluid among the two liquid chambers of the hydraulic cylinder is lower (hereinafter referred to as "low pressure chamber"). The occurrence of cavitation phenomenon is effectively suppressed.

Aspects of the invention

The low-pressure chamber liquid pressure drop preventing means is, for example, a means for opening the low-pressure chamber to atmospheric pressure, and when the stabilizer system has an accumulator for storing the hydraulic fluid at a relatively low pressure, the accumulator and the low-pressure chamber are communicated with each other. It is possible to adopt a means for causing the accumulator.

Further, the low pressure chamber liquid pressure drop preventing means may be realized by the control of the controller, or may be realized by some mechanism without being controlled by the controller. Which of the two liquid chambers becomes the low pressure chamber is determined by the roll direction of the vehicle body, that is, the turning direction of the vehicle. Therefore, when the low-pressure chamber liquid pressure drop preventing means is realized by the control of the controller, for example, the control depending on the direction of the lateral acceleration of the vehicle body may be executed.

It is a schematic diagram which shows the stabilizer system of 1st Example in which the 1st stabilizer device was provided for the front wheel, and the 2nd stabilizer device was provided for a rear wheel. It is a schematic diagram for demonstrating the operation of the 1st stabilizer apparatus. It is a schematic diagram for demonstrating the operation of the 2nd stabilizer apparatus. It is a flowchart which shows the stabilizer control program executed in the stabilizer system of 1st Embodiment. It is a schematic diagram which shows the state of the stabilizer system realized by the process which follows the stabilizer control program when the vehicle turns to the left. It is a schematic diagram which shows the state of the stabilizer system realized by the process which follows the stabilizer control program when a vehicle turns to the right. It is a schematic diagram which shows the stabilizer system of 2nd Embodiment which provided the 1st stabilizer device to the front wheel, and 2nd stabilizer device to the rear wheel. It is a flowchart which shows the stabilizer control program executed in the stabilizer system of 2nd Embodiment.

Hereinafter, two stabilizer systems, each of which is an embodiment of the present invention, will be described in detail with reference to the drawings as a mode for carrying out the claimable invention. In addition to the following examples, the present invention will be carried out in various forms with various modifications and improvements based on the knowledge of those skilled in the art, including the forms described in the above [Aspects of the invention]. be able to.

First Example

[1] Basic Configuration of Stabilizer System The stabilizer system of the first embodiment is a front wheel side stabilizer device mounted on the left and right front wheels 10FL and 10FR of the vehicle, as schematically shown in FIG. It includes a stabilizer device 12 and a second stabilizer device 14 which is a rear wheel side stabilizer device mounted on the left and right rear wheels 10RL and 10RR of the vehicle. In the following description, one of the left and right front wheels 10FL and 10FR is referred to as a front wheel 10F, and one of the left and right rear wheels 10RL and 10RR is referred to as a rear wheel 10R. One of the left and right rear wheels 10RL and 10RR may be referred to as a wheel 10 when it is not necessary to distinguish between front, rear, left and right. By the way, the left and right front wheels 10F are steering wheels that are steered when the vehicle turns.

(A) Configuration of the first stabilizer device Each of the front wheels 10FL and 10FR is suspended by a double wishbone type suspension device which is an independent suspension type suspension device. The first stabilizer device 12 includes a stabilizer bar 16 as a main component. The stabilizer bar 16 includes a central torsion bar portion 16t integrated with each other and left and right arm portions 16aL and 16aR, and the left and right arm portions 16aL and 16aR extend in the direction of the torsion bar portion 16t. It intersects the vehicle width direction, which is the extending direction.

The torsion bar portion 16t is provided with supported portions 16sL and 16sR on the left and right, and the stabilizer bar 16 is a part of the vehicle body (in the figure) by the support 22 at each of the left and right supported portions 16sL and 16sR. , A part of the car body is shaded) 24. Although not shown, the support 22 has a bush composed of an outer cylinder and a rubber elastic body, and the torsion bar portion 16t is rotatably supported around an axis. That is, the stabilizer bar 16 is supported by the vehicle body in a state where the torsion bar portion 16t is allowed to be twisted.

The tip of the left arm portion 16aL of the stabilizer bar 16 is connected to the lower arm 18L constituting the left suspension device via the cylinder 26, and the tip of the right arm portion 16aR is connected to the lower arm 18L constituting the left suspension device via the link rod 28. It is connected to the lower arm 18R constituting the suspension device. Incidentally, the lower arms 18L and 18R each function as a pair of wheel holding members that rotatably hold the left and right front wheels 10F and move up and down with respect to the vehicle body together with the held front wheels 10F. Further, although not shown, the other ends of the suspension spring and the shock absorber, one end of which is supported by the mount portion of the vehicle body, are connected to each of the lower arms 18L and 18R, although not shown. For the left and right pair of components such as the arm portions 16aL, 16aR, lower arms 18L, 18R, etc., which have the subscripts L and R attached to the reference numerals, one of the left and right pairs is distinguished from the left and right. When it is not necessary, it may be referred to as an arm portion 16a, a lower arm 18, or the like.

The cylinder 26 includes a housing 26h, a piston 26p that divides the inside of the housing 26h into two liquid chambers, an upper chamber 26cU and a lower chamber 26cL, and a piston rod 26r whose one end is connected to the piston 26p and extends from the housing 26h. Includes. The cylinder 26 is expandable and contractible, the upper chamber 26cU is a first liquid chamber whose volume increases when the cylinder 26 expands and the volume decreases when the cylinder 26 contracts, and the lower chamber 26cL contracts the cylinder 26. It functions as a second liquid chamber whose volume increases and decreases as it expands.

The first stabilizer device 12 includes an inter-chamber communication passage 30 for communicating the upper chamber 26cU and the lower chamber 26cL of the cylinder 26, and the first on-off valve is connected to the inter-chamber communication passage 30 in series with each other. 32, the second on-off valve 34 is arranged. Both the first on-off valve 32 and the second on-off valve 34 are normally closed solenoid valves that are opened by being excited, and switch between opening and closing of the inter-chamber communication passage 30. More specifically, by opening both the first on-off valve 32 and the second on-off valve 34, an inter-chamber communication state in which the upper chamber 26cU and the lower chamber 26cL communicate with each other is realized, and the first By closing at least one of the on-off valve 32 and the second on-off valve 34, an inter-chamber non-communication state in which the upper chamber 26cU and the lower chamber 26cL do not communicate with each other is realized. In other words, the first stabilizer device 12 selectively realizes a switching mechanism including the first on-off valve 32 and the second on-off valve 34, that is, an inter-room communication state and an inter-room communication state. It is provided with a switching mechanism 42 for this purpose.

The cylinder 26 is a so-called rod one-side extension cylinder, and the total of the internal capacity of the housing 26h, that is, the capacity of the upper chamber 26cU and the capacity of the lower chamber 26cL changes with expansion and contraction. In other words, there is a difference between the amount of hydraulic fluid flowing in and out of the upper chamber 26cU and the amount of hydraulic fluid flowing in and out of the lower chamber 26cL due to expansion and contraction. In order to compensate for this difference, that is, the volume change, the inter-chamber communication passage 30 has an inter-device communication passage 46 extending from between the first on-off valve 32 and the second on-off valve 34 toward the second stabilizer device 14. Via, it is connected to the accumulator 48 provided in the second stabilizer device 14.

The stabilizer system includes an electronic control unit (hereinafter, may be referred to as “ECU”) 55 that functions as a controller of the first stabilizer device 12, and the operation of the on-off valves 32 and 34 is controlled by the ECU 55. Will be. Although detailed description will be omitted, the ECU 55 includes a computer including a CPU, ROM, RAM, and the like, and a drive circuit for the first on-off valve 32 and the second on-off valve 34.

(B) Configuration of the Second Stabilizer Device The rear wheels 10RL and 10RR are suspended by a rigid axle type suspension device, and the second stabilizer device 14 is provided for the rear wheels 10RL and 10RR. Like the first stabilizer device 12, the second stabilizer device 14 includes a stabilizer bar 60 as a main component. The stabilizer bar 60 of the second stabilizer device 14 is also configured to include a central torsion bar portion 60t integrated with each other and left and right arm portions 60aL, 60aR, and the extending directions of the left and right arm portions 60aL, 60aR are , It intersects with the vehicle width direction, which is the extending direction of the torsion bar portion 60t.

The torsion bar portion 60t of the stabilizer bar 60 is provided with supported portions 60sL and 60sR on the left and right, and the stabilizer bar 60 is supported on the axle housing 62 via the support 64 in the supported portions 60sL and 60sR. Has been done. The axle housing 62 functions as a wheel holding portion in which both ends hold the rear wheels 10RL and 10RR, respectively, and swings as shown by the white arrows in FIG. 1 in response to the vertical movement of the rear wheels 10RL and 10RR with respect to the vehicle body. It is possible. Further, the support 64 has a bush composed of an outer cylinder and a rubber elastic body, similarly to the support 30 of the first stabilizer device 12 described above, and is the torsion bar portion 60t of the stabilizer bar 60. It allows rotation around the axis, that is, twisting.

Both ends of the stabilizer bar 60, that is, the tips of the left and right arm portions 60aL and 60aR are connected to a part 24 of the vehicle body, specifically, to the left and right portions in the vehicle width direction. Specifically, the tip of the right arm portion 60aR is connected via the link rod 66, and the tip of the left arm portion 60aL is connected via the link rods 68, 70 and the cylinder 72. Similar to the cylinder 28 of the first stabilizer device 12, the cylinder 72 has a housing 72h, a piston 72p arranged in the housing 72h, a base end portion connected to the piston 72p, and a tip portion (lower end portion) downward. It has a piston rod 72r extending from the housing 72h toward the housing 72h. The housing 72h is swingably supported by a part 24 of the vehicle body via a bush, and one end of the link rod 68 is the tip of the arm portion 60aL, the other end of the link rod 68 is one end of the link rod 70, and the link rod. The other end of 70 is connected to the housing 72h of the cylinder 72, respectively. Then, the tip of the piston rod 72r is connected to the intermediate portion of the link rod 68, so that it is simply connected to the tip of the arm portion 60aL on the left side of the stabilizer bar 60, that is, one end of the stabilizer bar 60. There is.

As shown by the white arrow in FIG. 1, the cylinder 72 can be expanded and contracted with the swing of the axle housing 62, and like the cylinder 26 of the first stabilizer device 12, the inside of the housing 70h is formed by the piston 72p. It is divided into an upper chamber 72cU and a lower chamber 72cL, which are two liquid chambers whose volumes vary due to the expansion and contraction. More specifically, the cylinder 72 has an upper chamber 72cU, which is a first liquid chamber whose volume increases when it expands and decreases when it contracts, and a cylinder 72 whose volume decreases when it expands and increases when it contracts. It has a lower chamber 72 cL, which is a second liquid chamber.

The second stabilizer device 14 includes an inter-chamber communication passage 74 for communicating the upper chamber 72cU and the lower chamber 72cL of the cylinder 72, and the first on-off valve is connected to the inter-chamber communication passage 74 in series with each other. 76, a second on-off valve 78 is arranged. Both the first on-off valve 76 and the second on-off valve 78 are normally open solenoid valves that are closed by being excited, and switch between opening and closing of the inter-chamber communication passage 74. More specifically, by opening both the first on-off valve 76 and the second on-off valve 78, an inter-chamber communication state in which the upper chamber 72cU and the lower chamber 72cL communicate with each other is realized, and the first By closing at least one of the on-off valve 76 and the second on-off valve 78, an inter-chamber non-communication state in which the upper chamber 72cU and the lower chamber 72cL do not communicate with each other is realized. In other words, the second stabilizer device 14 selectively realizes a switching mechanism including the first on-off valve 76 and the second on-off valve 78, that is, a room-to-room communication state and a room-to-room non-communication state. It is provided with a switching mechanism 80 for this purpose.

The cylinder 72 is also a so-called rod one-side extension cylinder, and the total of the internal capacity of the housing 72h, that is, the capacity of the upper chamber 72cU and the capacity of the lower chamber 72cL changes as the housing 72h expands and contracts. In other words, there is a difference between the amount of hydraulic fluid flowing in and out of the upper chamber 72cU and the amount of hydraulic fluid flowing in and out of the lower chamber 72cL due to expansion and contraction. In order to compensate for this difference, that is, the volume change, in the second stabilizer device 14, the accumulator 48 described above is connected to the inter-chamber communication passage 74 between the first on-off valve 76 and the second on-off valve 78. It is connected.

Further referring to the accumulator 48, the accumulator 48 serves both the accumulator required for the first stabilizer device 12 and the accumulator required for the second stabilizer device 14. The 1 stabilizer device 12 and the 2nd stabilizer device 14 are shared. As a result, the number of accumulators is reduced in this stabilizer system. Incidentally, in the present stabilizer system, it can be considered that the hydraulic pressure systems of the first stabilizer device 12 and the second stabilizer device 14 are connected by the inter-device communication passage 46 described above.

Further, the ECU 55 described above also has a drive circuit for the first on-off valve 76 and the second on-off valve 78 and also functions as a controller for the second stabilizer device 14, and the first on-off valve 76 and the second on-off valve The operation of the 78 is controlled by the ECU 55.

[2] Basic Operation of Stabilizer System The following describes the basic operations that can be performed in this stabilizer system for each of the first stabilizer device 12 and the second stabilizer device 14.

(A) Operation of the first stabilizer device As described above, when the first on-off valve 32 and the second on-off valve 34 constituting the switching mechanism 42 of the first stabilizer device 12 are in the closed state, An inter-chamber non-communication state is realized in which the upper chamber 26cU and the lower chamber 26cL of the cylinder 26 do not communicate with each other. As a result, the hydraulic fluid does not flow in or out of the upper chamber 26cU and the lower chamber 26cL. That is, the cylinder 26 is prohibited from expanding and contracting.

As shown in FIG. 2A, when the vehicle turns, the vehicle body tilts in the left-right direction, that is, rolls. Incidentally, FIG. 2A shows a state in which the vehicle body is turned to the left and the vehicle body is inclined to the right. When the expansion and contraction of the cylinder 26 is prohibited, the torsion bar portion 16t of the stabilizer bar 16 is twisted. The reaction force of this twist acts on the lower arms 18L and 18R via the left and right arm portions 16aL and 16aR, so that the roll of the vehicle body is suppressed. That is, the roll suppressing effect of the first stabilizer device 12 by the stabilizer bar 16 is activated.

On the other hand, as shown in FIG. 2B, when the first on-off valve 32 and the second on-off valve 34 constituting the switching mechanism 42 are in the valve open state, the upper chamber 26cU and the lower chamber of the cylinder 26 are in the open state. An inter-room communication state in which 26 cL communicates is realized. As a result, the inflow and outflow of the hydraulic fluid between the upper chamber 26cU and the lower chamber 26cL is allowed, and the expansion and contraction of the cylinder 26 is allowed.

As shown in FIG. 2B, consider a case where an external input acts on the left and right front wheels 10FL and 10FR in a state where the expansion and contraction of the cylinder 26 as described above is allowed. By the way, FIG. 2B shows a case where the vehicle travels off-road (where the ground is rough), the left front wheel 10FL rebounds, and the right front wheel 10FR bounces. ing. In this case, the torsion bar portion 16t of the stabilizer bar 16 is hardly twisted. That is, the stabilizer bar 16 exerts no force on the lower arms 18L and 18R. Therefore, even when traveling on rough ground, it is possible to effectively absorb the road surface input to each of the left and right front wheels 10FL and 10FR. That is, the roll suppressing effect of the first stabilizer device 12 is invalidated.

(B) Operation of the Second Stabilizer Device As described above, both the first on-off valve 76 and the second on-off valve 78 constituting the switching mechanism 80 of the second stabilizer device 14 are closed. At this time, an inter-chamber non-communication state is realized in which the upper chamber 72cU and the lower chamber 72cL of the cylinder 72 do not communicate with each other. In this state, the inflow and outflow of the hydraulic fluid to the upper chamber 72cU and the lower chamber 72cL is prohibited, and the expansion and contraction of the cylinder 72 is prohibited.

As shown in FIG. 3A, when the vehicle turns, the vehicle body tilts in the left-right direction, that is, rolls. Incidentally, FIG. 3A shows a state in which the vehicle body is turned to the left and the vehicle body is inclined to the right. When the vehicle body is tilted, the axle housing 62 that supports the torsion bar portion 60t of the stabilizer bar 60 in the supported portions 60sL and 60sR swings relatively with respect to the vehicle body. When the expansion and contraction of the cylinder 72 is prohibited, the positions of the tips of the arms 60aL and 60aR of the stabilizer bar 60 in the vertical direction with respect to the vehicle body do not substantially change. Therefore, the torsion bar portion 60t of the stabilizer bar 60 is twisted by the swing of the axle housing 62. The reaction force of this twist acts on a part 24 of the vehicle body via the left and right arm portions 60aL, 60aR and the cylinder 72, so that the roll of the vehicle body is suppressed. That is, the roll suppressing effect of the second stabilizer device 14 by the stabilizer bar 60 is activated.

On the other hand, as shown in FIG. 3B, when both the first on-off valve 76 and the second on-off valve 78 are in the valve open state, the upper chamber 72cU and the lower chamber 72cL of the cylinder 72 mutually communicate with each other. An inter-chamber communication state is realized, and the hydraulic fluid is allowed to flow in and out of the upper chamber 72 cU and the lower chamber 72 cL. The cylinder 72 is allowed to expand and contract with almost no limitation.

As shown in FIG. 3B, consider a case where an external input acts on the left and right rear wheels 10RL and 10RR while the cylinder 72 is allowed to expand and contract. Incidentally, FIG. 3B shows a case where an external input such that the left rear wheel 10RL rebounds and the right rear wheel 10RR rebounds acts on the off-road. In this case, the axle housing 62 swings, and the swing causes the stabilizer bar 60 supported by the axle housing 62 in the supported portions 60sL and 60sR to swing. However, since the expansion and contraction of the cylinder 72 is allowed, the torsion bar portion 60t of the stabilizer bar 60 is hardly twisted even by the swing of the stabilizer bar 60. That is, the stabilizer bar 60 exerts no force on the swing of the axle housing 62 with respect to the vehicle body. Therefore, even when traveling on rough ground, it is possible to effectively absorb the road surface input to each of the left and right rear wheels 10RL and 10RR. That is, the roll suppressing effect of the second stabilizer device 14 is invalidated.

(C) Roll suppression effect and roll rigidity by the stabilizer device As described above, the first stabilizer device 12 and the second stabilizer device 14 each exhibit a roll suppression effect when the inter-chamber non-communication state is realized. Will be done. Therefore, in the first stabilizer device 12 and the second stabilizer device 14, the switching mechanism 42 and the switching mechanism 80 for selectively realizing the inter-room communication state and the inter-room communication state are the stabilizer bar 16 and the stabilizer, respectively. It can be considered as a mechanism for switching between enabling and disabling the roll suppressing effect of the bar 60.

Speaking of the degree of exerting the roll suppressing effect, when both the first stabilizer device 12 and the second stabilizer device 14 exert the roll suppressing effect, the roll rigidity on the front wheel 10F side is the roll rigidity on the rear wheel 10R side. The first stabilizer device 12 and the second stabilizer device 14 are configured so as to be higher. With this configuration, the vehicle has an understeer tendency and exhibits stable turning behavior. The first on-off valve 32 and the second on-off valve 34 of the switching mechanism 42 of the first stabilizer device 12 are normally closed valves, and the first on-off valve 76 and the second on-off valve of the switching mechanism 80 of the second stabilizer device 14 are normally closed. Since the valve 78 is a normally open valve, the vehicle tends to have an understeer tendency even if, for example, an electrical failure occurs in the stabilizer system.

[C] Control of the stabilizer system in consideration of the cavitation phenomenon in the cylinder (a) Occurrence of the cavitation phenomenon and means for preventing it The first stabilizer device 12 and the second stabilizer device 14 are in a state where the roll suppression effect is enabled, respectively. Now, let's consider the case where the car body rolls. When the vehicle turns to the left and the vehicle body rolls to the right, as shown in FIG. 2A, the pressure of the hydraulic fluid in the lower chamber 26cL of the cylinder 26 of the first stabilizer device 12 rises, and FIG. The pressure of the hydraulic fluid in the upper chamber 26cU indicated by ★ decreases. Similarly, as shown in FIG. 3A, the pressure of the hydraulic fluid in the lower chamber 72cL of the cylinder 72 of the second stabilizer device 14 rises, and the pressure of the hydraulic fluid in the upper chamber 72cU indicated by ★ in the figure increases. Decreases.

Although not shown, conversely, when the vehicle turns to the right and the vehicle body rolls to the left, the pressure of the hydraulic fluid in the upper chamber 26cU of the cylinder 26 of the first stabilizer device 12 rises, and the lower chamber The pressure of the hydraulic fluid in 26 cL drops. Similarly, the pressure of the hydraulic fluid in the upper chamber 72 cL of the cylinder 72 of the second stabilizer device 14 increases, and the pressure of the hydraulic fluid in the lower chamber 72 cL decreases.

The upper chamber 26cU and the lower chamber 26cL of the cylinder 26 are collectively referred to as the liquid chamber 26c, and the upper chamber 72cU and the lower chamber 72cL of the cylinder 72 are collectively referred to as the liquid chamber 72c. The decrease in pressure leads to a negative pressure (a state lower than the atmospheric pressure) in the liquid chambers 26c and 72c. When the degree of the negative pressure is large, a cavitation phenomenon occurs in the liquid chambers 26c and 72c.

The cavitation phenomenon is a phenomenon in which bubbles are generated in the liquid chambers 26c and 72c and the bubbles burst, which contributes to the generation of abnormal noise in the system. Therefore, it is desirable to prevent the cavitation phenomenon.

On the other hand, it is possible to activate the roll suppressing effect of the first stabilizer device 12 and the second stabilizer device 14 only by prohibiting the outflow of the hydraulic fluid from the liquid chambers 26c and 72c where the pressure of the hydraulic fluid rises. be.

Therefore, in the stabilizer system of the present embodiment, as a means for preventing the cavitation phenomenon, in a state where the roll suppressing effect is enabled, the upper chamber 26cU, the lower chamber 26cL, the cylinder 72 upper chamber 72cU, and the lower chamber 72cL of the cylinder 26 are enabled. A low-pressure chamber liquid pressure drop preventing means for preventing a drop in the pressure of each of the hydraulic fluids having a lower pressure is provided.

(B) Control of the stabilizer system adopting the low pressure chamber hydraulic pressure drop preventing means The control of the stabilizer system adopting the low pressure chamber hydraulic pressure drop preventing means will be described below. This control is performed by the ECU 55 repeatedly executing the stabilizer control program shown in the flowchart of FIG. 4 at a short time pitch (for example, several msec to several tens of msec). The control process according to the program will be described below.

The vehicle is provided with a lateral acceleration sensor 90 (see FIG. 1) for detecting the lateral acceleration Gy of the vehicle body. First, in step 1 (hereinafter abbreviated as “S1”, the same applies to other steps). , The lateral acceleration Gy is acquired based on the detection of the lateral acceleration sensor 90. By the way, the lateral acceleration Gy when the vehicle turns to the left and the vehicle body rolls to the right is a positive value, and the lateral acceleration Gy when the vehicle turns to the right and the vehicle body rolls to the left is. , Will be a negative value.

In the following S2, it is determined whether or not the absolute value of the acquired lateral acceleration Gy is less than the threshold lateral acceleration Gy _TH . The threshold lateral acceleration Gy _TH is intended to have a certain width with respect to the straight-ahead state, that is, to provide a dead zone for the turning determination, and is set to a value in consideration of the purpose. .. When the absolute value of the lateral acceleration Gy is less than the threshold lateral acceleration Gy _TH , in S3, it is considered that the vehicle is not turning, that is, it is going straight, and the first stabilizer device 12 and the second stabilizer device 12 Both roll-suppressing effects of 14 are nullified. Specifically, both the first on-off valve 32 and the second on-off valve 34 constituting the switching mechanism 42 of the first stabilizer device 12 are opened, and the switching mechanism 80 of the second stabilizer device 14 is configured. Both the first on-off valve 76 and the second on-off valve 78 are opened.

On the other hand, when it is determined in S2 that the absolute value of the lateral acceleration Gy is equal to or greater than the threshold lateral acceleration Gy _TH , is the positive or negative of the lateral acceleration Gy, that is, whether the value of the lateral acceleration Gy is larger than 0 in S4? Whether or not it is determined. When it is determined that the value of the lateral acceleration Gy is larger than 0, it is considered that the vehicle is turning to the left in S5, and the roll to the right of the vehicle body is suppressed while preventing the above cavitation phenomenon. As shown in FIG. 5, the first on-off valve 32 constituting the switching mechanism 42 of the first stabilizer device 12 is set to the valve open state, and the second on-off valve 34 is set to the valve closed state. Further, as shown in FIG. 5, the first on-off valve 76 constituting the switching mechanism 80 of the second stabilizer device 14 is set to the valve open state, and the second on-off valve 78 is set to the valve closed state. As a result, the upper chamber 26cU of the cylinder 26 and the upper chamber 72cU of the cylinder 72 are opened to the accumulator 48, and the lower chamber 26cL of the cylinder 26 and the lower chamber 72cL of the cylinder 72 are sealed, so that the first stabilizer device 12 and the first stabilizer device 12 and the first are sealed. In both of the two stabilizer devices 14, the cavitation phenomenon is prevented and the roll suppressing effect is effective.

On the other hand, when it is determined in S4 that the value of the lateral acceleration Gy is 0 or less, it is considered that the vehicle is turning to the right in S6, and the vehicle body is prevented from the above-mentioned cavitation phenomenon. In order to suppress the roll to the left, as shown in FIG. 6, the first on-off valve 32 constituting the switching mechanism 42 of the first stabilizer device 12 is closed, and the second on-off valve 34 is opened. It is considered to be in a state. Further, as shown in FIG. 6, the first on-off valve 76 constituting the switching mechanism 80 of the second stabilizer device 14 is in the closed state, and the second on-off valve 78 is in the open state. As a result, the lower chamber 26cL of the cylinder 26 and the lower chamber 72cL of the cylinder 72 are opened to the accumulator 48, and the upper chamber 26cU of the cylinder 26 and the upper chamber 72cU of the cylinder 72 are sealed, so that the first stabilizer device 12 and the first stabilizer device 12 and the first are sealed. In both of the two stabilizer devices 14, the cavitation phenomenon is prevented and the roll suppressing effect is effective.

That is, in the stabilizer system of the present embodiment, only one of the first on-off valve 32 and the second on-off valve 34 constituting the switching mechanism 42 is set to the valve open state according to the turning direction of the vehicle, and the switching mechanism 80 is set. The two liquid chambers 26c of the cylinder 26 are controlled to prevent the cavitation phenomenon in the cylinder 26 and the cylinder 72 by controlling the valve so that only one of the first on-off valve 76 and the second on-off valve 78 is opened. Low pressure chamber liquid pressure drop preventing means for preventing the pressure of the lower pressure one from dropping and preventing the pressure of the lower pressure one of the two liquid chambers 72c of the cylinder 72 from dropping. Is configured.

(C) Modification example In the stabilizer system of the first embodiment, the cylinder 26 is arranged on the left front wheel 10FL side in the first stabilizer device 12, and the cylinder 26 is arranged on the left rear wheel 10RL side in the second stabilizer device 14. 72 was disposed, but as a stabilizer system of a modified example, although not shown, the cylinder 26 is disposed on the right front wheel 10FR side in the first stabilizer device 12, and the right in the second stabilizer device 14. It is also possible to construct a stabilizer system in which the cylinder 72 is arranged on the rear wheel 10RR side.

In such a stabilizer system, contrary to the stabilizer system of the first embodiment, when the vehicle turns to the left, the first on-off valve 32 constituting the switching mechanism 42 of the first stabilizer device 12 is in a closed state. If the second on-off valve 34 is opened, the first on-off valve 76 constituting the switching mechanism 80 of the second stabilizer 14 is closed, and the second on-off valve 78 is opened. Well, when the vehicle turns to the right, the first on-off valve 32 constituting the switching mechanism 42 of the first stabilizer device 12 is in the open state and the second on-off valve 34 is in the closed state. 2. The first on-off valve 76 constituting the switching mechanism 80 of the stabilizer device 14 may be in the valve open state, and the second on-off valve 78 may be in the valve closed state.

Second Example

In the stabilizer system of the first embodiment, in short, the low pressure chamber hydraulic pressure drop preventing means is configured by controlling the on-off valve according to the turning direction of the vehicle. For example, it is schematically shown in FIG. As in the stabilizer system of the second embodiment, it is also possible to configure a low pressure chamber liquid pressure drop preventing means that does not depend on such control.

If the stabilizer system of the second embodiment is described by using the same reference numerals for the components having the same functions as the stabilizer system of the first embodiment, the stabilizer system of the second embodiment is switched instead of the switching mechanism 42. It includes a first stabilizer device 12'that employs a mechanism 42'and a second stabilizer device 14' that employs a switching mechanism 80'instead of the switching mechanism 80. The switching mechanism 42'has two check valves 94 arranged in parallel with the first on-off valve 32 and the second on-off valve 34, respectively, and the switching mechanism 80'has a first on-off valve. It has two check valves 96 arranged in parallel with 76 and the second on-off valve 78, respectively.

When one of the two liquid chambers 26c of the cylinder 26 becomes a negative pressure due to the operation of the check valve 94, the inflow of the hydraulic fluid from the accumulator 48 into either of them is allowed, and the inflow of the hydraulic fluid is allowed into either of them. When one of the two liquid chambers 72c of the cylinder 72 becomes a negative pressure due to the action of the check valve 96, the inflow of the hydraulic fluid from the accumulator 48 into either of them is permitted. That is, in the stabilizer system of the second embodiment, the low-pressure chamber liquid pressure drop preventing means is configured by the two check valves 94 of the switching mechanism 42'and the two check valves 96 of the switching mechanism 80'. ..

In the stabilizer system of the second embodiment, the stabilizer control program shown in the flowchart of FIG. 8 is executed by the ECU 55. Briefly explaining the process according to this program, first, in S11, the lateral acceleration Gy is acquired, and then in S12, it is determined whether or not the absolute value of the lateral acceleration Gy is less than the threshold lateral acceleration Gy _TH . To. When the absolute value of the lateral acceleration Gy is less than the threshold lateral acceleration Gy _TH , it is considered that the vehicle is traveling straight, and in S13, both the first on-off valve 32 and the second on-off valve 34 of the switching mechanism 42', Both the first wheel required braking force F _WH ^* determination on-off valve 76 and the second on-off valve 78 of the switching mechanism 80'are opened. On the other hand, when the absolute value of the lateral acceleration Gy is equal to or greater than the threshold lateral acceleration Gy _TH , the first on-off valve 32 and the second on-off valve 34 of the switching mechanism 42'in S14 regardless of the turning direction of the vehicle. Both and both the first on-off valve 76 and the second on-off valve 78 of the switching mechanism 80'are closed.

10FL, 10FR, 10RL, 10RR: Wheel 12: 1st stabilizer device 14: 2nd stabilizer device 16: Stabilizer bar 26: Cylinder 26cU: Upper chamber 26cL: Lower chamber 28: Link rod 30: Inter-chamber communication passage 32: 1st On-off valve 34: Second on-off valve 42, 42': Switching mechanism 46: Inter-device communication passage 48: Accumulator 55: Electronic control unit (ECU) [Controller] 60: Stabilizer bar 72: Cylinder 72cU: Upper chamber 72cL: Lower chamber 74: Inter-chamber communication passage 76: 1st on-off valve 78: 2nd on-off valve 80, 80': Switching mechanism 94: Check valve 96: Check valve

Claims (1)

It is a stabilizer system installed in the vehicle.
(a) Stabilizer bar supported by the vehicle body and connected to a wheel holding member that holds the wheels rotatably and is allowed to move up and down with respect to the vehicle body, and (b) the stabilizer bar and the vehicle body or the wheel holding member. A hydraulic cylinder in which two liquid chambers whose volumes change with the vertical movement of the wheel holding member are partitioned between the two liquid chambers, and (c) the two liquids of the hydraulic cylinder. A stabilizer device having a switching mechanism for switching between enabling and disabling the roll suppressing effect of the vehicle body by the stabilizer bar by switching between prohibition and permissible of the inflow and outflow of the hydraulic fluid into the chamber.
It is equipped with a controller that controls the switching mechanism of the stabilizer device.
The stabilizer system further
In a state where the roll suppressing effect of the stabilizer device is enabled, the pressure of the hydraulic fluid of the two liquid chambers of the hydraulic cylinder, whichever is lower, is reduced in the low pressure chamber to prevent the pressure from decreasing. Stabilizer system featuring preventive measures.

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