Suspension system for vehicle seats and vehicle seats

Abstract

To provide a suspension system for vehicle seats and a vehicle seat for improving the ride comfort of occupants. [Solution] The suspension device of this disclosure comprises a lower member, an upper member, a lifting mechanism, a spring, a variable damper with adjustable damping force, a first sensor for detecting the vertical speed of the upper member, a second sensor for detecting the vertical speed of the lower member, and a control device capable of controlling the damping force of the variable damper. The control device selectively executes a normal control mode and a bottoming-out prevention control mode. In the bottoming-out prevention control mode, when the first sensor or the second sensor detects that the speed moving upward or downward exceeds a reference speed, the damping force of the variable damper is adjusted to the maximum damping force.

Description

Technical Field

[0001] The present disclosure relates to a suspension device for a vehicle seat and a vehicle seat.

Background Art

[0002] Patent Document 1 below describes a vehicle seat including biasing means composed of an air spring, damping means for absorbing seat vibrations, and a locking mechanism capable of locking changes in the height of the seat.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a vehicle seat as described in Patent Document 1 above, in order to more effectively attenuate vibrations during vehicle travel, some have adopted a characteristic variable damper (sometimes referred to as a "variable damping damper") capable of adjusting the damping force as damping means. When using a characteristic variable damper, it becomes possible to adjust the damping force in consideration of seat vibrations, so it is possible to improve the riding comfort of the seated passengers. However, there is room for improvement in how to specifically control the damping force of the characteristic variable damper.

[0005] In consideration of the above points, an object of the present disclosure is to provide a suspension device for a vehicle seat and a vehicle seat for improving the riding comfort of passengers.

Means for Solving the Problems

[0006] A suspension device for a vehicle seat according to the first embodiment comprises: a lower member fixed to the floor of the vehicle body; an upper member positioned above the lower member and connected to the seat body; a lifting mechanism connecting the upper member to the lower member so as to be able to move up and down; a spring that is elastically deformed by the lifting and moving of the upper member; a variable damper with adjustable damping force provided between the lower member and the upper member; a first sensor for detecting the vertical speed of the upper member; a second sensor for detecting the vertical speed of the lower member; and a control device capable of controlling the damping force of the variable damper based on the detection result of at least one of the first and second sensors. The control device selectively executes two modes: a normal control mode in which, when it detects that the speed at which the first sensor or the second sensor is moving upward or downward is below a predetermined reference speed, the damping force of the variable damper is adjusted to reduce the vertical speed of the upper member relative to the lower member in a shorter time than when the damping force of the variable damper is set to a constant damping force, and to avoid bottoming out where the upper member and the lower member come into contact; and a bottoming-out prevention control mode in which, when it detects that the speed at which the first sensor or the second sensor is moving upward or downward exceeds the reference speed, the damping force of the variable damper is adjusted to the maximum damping force.

[0007] In the suspension system for a vehicle seat of the first embodiment, the control device executes a normal control mode in which, when the speed of the first sensor or the second sensor moving upward or downward is detected to be below a predetermined reference speed, the damping force of the variable damper is adjusted to reduce the vertical speed of the upper member relative to the lower member in a shorter time than when the damping force of the variable damper is set to a constant damping force, and to avoid bottoming out where the upper member and the lower member come into contact. In this normal control mode, vibration (vertical speed of the upper member relative to the lower member) can be efficiently dampened while suppressing bottoming out where the upper member and the lower member come into contact, thereby improving the ride comfort of the occupants. Furthermore, when the control device detects that the speed of the first sensor or the second sensor moving upward or downward exceeds the reference speed, it executes a bottoming out prevention control mode in which the damping force of the variable damper is adjusted to the maximum damping force. This prevents bottoming out when the speed at which the first or second sensor moves upward or downward exceeds the reference speed. As a result, the deterioration of the occupants' ride comfort due to bottoming out can be suppressed.

[0008] In the suspension device for a vehicle seat of the second embodiment, the control device executes the bottoming-out prevention control mode for a predetermined time when it detects that the speed at which the second sensor is moving upward exceeds the reference speed.

[0009] In the suspension system for a vehicle seat of the second embodiment, bottoming out during the specified time can be avoided.

[0010] In the suspension device for a vehicle seat of the third embodiment, the control device executes the bottoming-out prevention control mode for a predetermined time whenever the speed at which the second sensor moves upward exceeds the reference speed.

[0011] In the suspension system for a vehicle seat of the third embodiment, whenever the second sensor detects that the upward speed exceeds the reference speed, a bottoming-out prevention control mode is executed for a predetermined time. This makes it possible to avoid bottoming out during the predetermined time.

[0012] The suspension device for a vehicle seat of the fourth embodiment is a suspension device for a vehicle seat of any one of the first to third embodiments, wherein the control device, after executing the bottoming-out prevention control mode, executes a return control mode in which it adjusts the damping force of the variable characteristic damper so that the damping force of the variable characteristic damper gradually approaches the damping force of the variable characteristic damper in the normal control mode, and then executes the normal control mode.

[0013] In the suspension system for a vehicle seat of the fourth embodiment, the control device executes a bottoming-out prevention control mode, then executes a return control mode to adjust the damping force of the variable damper so that the damping force of the variable damper gradually approaches the damping force of the variable damper in the normal control mode, and then executes the normal control mode. In this way, by executing the return control mode before executing the normal control mode, it is possible to suppress the unnatural feeling of change in ride comfort caused by a sudden change in the damping force of the variable damper.

[0014] A fifth embodiment of a vehicle seat comprises a seat body on which an occupant sits, and a suspension device for a vehicle seat of any one of the first to fourth embodiments, to which the seat body is connected to the upper member.

[0015] In the fifth embodiment of the vehicle seat, vibration damping can be efficiently performed while suppressing bottoming out where the upper member and the lower member come into contact, thereby providing a vehicle seat with good occupant comfort. [Effects of the Invention]

[0016] The suspension system and vehicle seats described above can improve the ride comfort of the occupants.

Brief Description of the Drawings

[0017] [Figure 1] It is a schematic perspective view showing an example of a vehicle seat according to an embodiment of the present disclosure. [Figure 2] It is a schematic perspective view showing an example of a suspension device of a vehicle seat according to an embodiment of the present disclosure. [Figure 3] It is a view schematically showing the vehicle seat of FIG. 1. [Figure 4] It is a block diagram showing an example of the hardware configuration of the control device shown in FIG. 1. [Figure 5] It is an explanatory view schematically showing the operating state of the suspension device during vehicle travel. [Figure 6] It is a list showing an example of the control mode in each section shown in FIG. 5. [Figure 7] It is a list showing another example of the control mode in each section shown in FIG. 5. [Figure 8] It is a graph showing the relationship between time and the vertical speed of the seat body. [Figure 9] It is a graph showing the relationship between time and the damping force of the characteristic variable damper. [Figure 10] It is a graph showing the relationship between time and the damping force of the characteristic variable damper.

Embodiments for Carrying Out the Invention

[0018] Hereinafter, each embodiment for carrying out the present disclosure will be described with reference to the drawings. In the following, the scope necessary for the description for achieving the object of the present disclosure is schematically shown, and mainly the scope necessary for the description of the corresponding part of the present disclosure will be described, and the parts where the description is omitted shall be based on known techniques. Also, in the drawings, some reference numerals may be omitted for the sake of easy viewing of the drawings.

[0019] Figure 1 is a schematic perspective view showing an example of a vehicle seat according to one embodiment of the present disclosure. As shown in Figure 1, the vehicle seat 10 according to one embodiment of the present disclosure includes a seat body 11 on which an occupant sits and a suspension device 12 to which the seat body 11 is connected. The arrows FR and UP shown in the figure indicate the front and top of the vehicle seat 10, respectively, and the arrow W indicates the width direction (or left-right direction) of the vehicle seat 10. Hereafter, when simply referring to the front, back, left, right, up, and down directions, these directions will be relative to the vehicle seat.

[0020] The seat body 11 is a component on which the occupant sits, and may include, for example, a seat cushion 11A that supports the occupant's buttocks and thighs, a seat back 11B that supports the occupant's back, and a headrest 11C that supports the occupant's head.

[0021] Figure 2 is a schematic perspective view showing an example of a suspension device for a vehicle seat according to one embodiment of the present disclosure. As shown in Figure 2, the suspension device 12 includes at least a lower member 20, an upper member 30, an X-link 40 as an example of a lifting mechanism disposed between the upper member 30 and the lower member 20, an air spring 60 as an example of a spring, and a variable damper 50. The suspension device 12 of this embodiment can be said to be a so-called "semi-active" type suspension, including the variable damper 50. In this embodiment, the X-link 40 is exemplified as a lifting mechanism, but other mechanisms that allow the seat body 11 to be raised and lowered, such as well-known mechanisms such as a sliding mechanism, can also be used. Similarly, the air spring 60 can also be replaced with other biasing means that can elastically support the seat body 11. Furthermore, the suspension device 12 may include components other than those described above, such as a locking mechanism that limits the vertical vibration of the seat body 11 relative to the vehicle body.

[0022] The lower member 20 is a member fixed to the floor portion 13 of the vehicle body (see Figure 3). This lower member 20 may include a pair of left and right lower rails 21, a lower-side connecting frame 22 that connects the front ends and rear ends of the pair of lower rails 21, and a lower bracket 23 that spans between the pair of lower rails 21. Of these, the pair of lower rails 21 can be made of, for example, press-formed metal plates and may be elongated members in the front-rear direction. The pair of lower rails 21 may have a substantially U-shape with the inner sides in the left-right direction open when viewed from the front. The lower-side connecting frame 22 and the lower bracket 23 can also be made of press-formed metal plates. Note that in Figure 2, the rear lower-side connecting frame 22 is hidden by other members. In this embodiment, the case in which the lower member 20 is fixed to the floor portion 13 is illustrated, but the lower member 20 may also be part of the floor portion 13.

[0023] The upper member 30 is positioned above the lower member 20 and is the member to which the seat body 11 is connected. This upper member 30 may include a pair of left and right upper rails 31, an upper-side connecting frame 32 that connects the front ends and rear ends of the pair of upper rails 31, and an upper bracket 33 that spans between the pair of upper rails 31. Of these, the pair of upper rails 31 may be positioned parallel to each other above the pair of lower rails 21. The pair of upper rails 31 can be made of, for example, a press-formed metal plate and may be a long member in the front-rear direction. The pair of upper rails 31, like the pair of lower rails 21, may have a substantially U-shape with the inner sides in the left-right direction open when viewed from the front. These upper rails 31 may be connected to the pair of lower rails 21 positioned below them via an X-link 40. The seat body 11 is connected to these upper rails 31, for example, via a well-known seat slide mechanism. Furthermore, the upper connecting frame 32 and the upper bracket 33 can also be constructed from press-formed metal plates. In this embodiment, the upper member 30 is shown as a member connected to the seat body 11, but the upper member 30 may be a part of the seat body 11, specifically, for example, the cushion frame (not shown) within the seat cushion 11A.

[0024] The X-link 40 connects the upper member 30 to the lower member 20 so that it can move up and down. One X-link 40 is provided between the lower rail 21 and the upper rail 31, and can be constructed by combining a pair of link arms in an X shape. The longitudinal middle sections of this pair of link arms may be rotatably connected. One of the pair of link arms constituting the X-link 40 may have its front end rotatably and slidably fixed to the upper rail 31, and its rear end rotatably fixed behind the lower rail 21. The other link arm of the pair of link arms constituting the X-link 40 may have its front end rotatably and slidably fixed to the lower rail 21, and its rear end rotatably fixed behind the upper rail 31. The specific lifting and lowering structure of the X-link 40 is well known, so a detailed explanation is omitted here.

[0025] The air spring 60 is a member that deforms elastically as the upper member 30 moves up and down, and elastically supports the seat body 11. This air spring 60 may be positioned between the upper bracket 33 and the lower bracket 23. The air spring 60 can be, for example, a substantially cylindrical member with its axis in the vertical direction. The upper end of the air spring 60 may be fixed to the upper bracket 33, and the lower end of the air spring 60 may be fixed to the lower bracket 23. This air spring 60 receives a compressive load between the upper bracket 33 and the lower bracket 23, and can bias the upper bracket 33 upward relative to the lower bracket 23. This air spring 60 can deform elastically as the X-link 40 expands and contracts, i.e., as the upper rail 31 moves up and down. In this embodiment, an example is shown in which the air spring 60 is positioned between the upper bracket 33 and the lower bracket 23, and its ends are fixed to the upper bracket 33 and the lower bracket 23, respectively, but the structure is not limited to this. For example, the air spring 60 may be placed inside the X-link 40, and its end may be fixed to the end of the X-link 40 or to the upper member 30 and the lower member 20, respectively.

[0026] The air spring 60 can be configured to receive compressed air, for example, from an air compressor that constitutes the vehicle's air brake system, via an air tube or the like. As air is supplied, the air spring 60 expands upward, raising the height of the left and right upper rails 31 and the seat body 11. Conversely, as air is exhausted, the air spring 60 contracts downward, lowering the height of the left and right upper rails 31 and the seat body 11. Note that the raising and lowering operation of the upper member 30 is not limited to the air spring 60 described above, and may be achieved by other actuators.

[0027] The variable damper (sometimes called a "shock absorber") 50 is provided between the lower member 20 and the upper member 30 and is a member having a predetermined damping force capable of absorbing vibrations of the air spring 60. One end of the variable damper 50 may be directly connected to the lower member 20, or indirectly connected via a part of the X-link 40 connected to the lower member 20. Similarly, the other end of the variable damper 50 may be directly connected to the upper member 30, or indirectly connected via a part of the X-link 40 connected to the upper member 30. Furthermore, the variable damper 50 is a damper whose characteristics, i.e., damping force, can be adjusted. For example, the variable damper 50 can be a hydraulic cylinder type damper, or an MR damper using magnetorheological fluid (MR fluid). The load of the occupant seated on the seat body 11 is elastically supported by the air spring 60, and vibrations of the seat body 11 are absorbed by the variable damper 50. The specific method for adjusting the damping force of the variable damper 50 will be described later.

[0028] Figure 3 is a schematic diagram of the vehicle seat shown in Figure 1. In addition to the components described above, the suspension device 12 of this embodiment further includes two sensors capable of detecting vibrations occurring in the vehicle seat 10. Specifically, it further includes an upper-side acceleration sensor 35 as an example of a first sensor capable of detecting the vertical velocity of the upper member 30, and a lower-side acceleration sensor 25 as an example of a second sensor capable of detecting the vertical velocity of the lower member 20. In this embodiment, the case in which acceleration sensors are used for the first and second sensors is illustrated, but other sensors capable of detecting velocity can also be used for the first and second sensors.

[0029] The lower acceleration sensor 25 can be attached, for example, to one of the lower rails 21, to detect the vertical speed of the lower member 20 and the floor portion 13 of the vehicle body to which the lower member 20 is fixed. The lower acceleration sensor 25 can detect vibrations of the vehicle body caused by irregularities in the road surface R via the floor portion 13 of the vehicle body and the wheels 14. The installation position of the lower acceleration sensor 25 is not particularly limited as long as the vertical speed of the lower member 20 can be detected. Specifically, the lower acceleration sensor 25 may be installed on the floor portion 13 to which the lower member 20 is connected.

[0030] The upper-side acceleration sensor 35 can be attached, for example, to one of the upper rails 31, to detect the vertical speed of the upper member 30 and the seat body 11 connected to the upper member 30. This upper-side acceleration sensor 35 can detect vibrations of the seat body 11 caused by vibrations of the vehicle body. The installation position of the upper-side acceleration sensor 35 is not particularly limited as long as the vertical speed of the upper member 30 can be detected. Specifically, the upper-side acceleration sensor 35 may be installed on the seat cushion 11A to which the upper member 30 is connected.

[0031] The suspension device 12 for the vehicle seat of this embodiment further includes, in addition to the components described above, a control ECU 70 as an example of a control device for controlling the suspension device 12. This control ECU 70 is capable of controlling the damping force of the variable damper 50 based on the detection results of the lower acceleration sensor 25 and the upper acceleration sensor 35. In addition to controlling the variable damper 50, the control ECU 70 may also be capable of adjusting the seat height by operating the X-link 40 and controlling the locking mechanism of the suspension device (not shown).

[0032] Figure 4 is a block diagram showing an example of the hardware configuration of the control ECU shown in Figure 1. The control ECU 70 may include a CPU (Central Processing Unit) 71, ROM (Read Only Memory) 72, RAM (Random Access Memory) 73, storage 74, and input / output I / F 75. The CPU 71, ROM 72, RAM 73, storage 74, and input / output I / F 75 are connected to each other via an internal bus 76 so that they can communicate with one another.

[0033] The CPU 71 is a central processing unit that can execute various programs and control various parts. Specifically, the CPU 71 can read a program from the ROM 72 and execute the program using the RAM 73 as a working area. In this embodiment, the program is stored in the ROM 72.

[0034] ROM 72 can store various programs and data. RAM 73 can temporarily store programs or data as a working area. Furthermore, storage 74 consists of an HDD (Hard Disk Drive) or SSD (Solid State Drive) and can store various programs, including the operating system.

[0035] The input / output interface 75 is an interface capable of transmitting control signals to each component of the suspension device 12 and collecting information acquired by each component. The input / output interface 75 may be electrically connected to at least the lower acceleration sensor 25, the upper acceleration sensor 35, and the variable damper 50. The control ECU 70 can control the variable damper 50 by using the CPU 71 to determine the control mode of the variable damper 50 based on the detection results of the lower acceleration sensor 25 and the upper acceleration sensor 35 input via the input / output interface 75, and by transmitting a control signal containing information about the determined control mode via the input / output interface 75. Details of the control modes and the process of determining the control mode in the CPU 71 will be described later.

[0036] The CPU 71, having acquired the detection results from the lower acceleration sensor 25 and the upper acceleration sensor 35, can calculate from these detection results whether the upper member 30 and the seat body 11 connected to the upper member 30 are rising or falling, and whether the force acting on the variable damper 50 is in the compressive or elongating direction.

[0037] Furthermore, the variable damper 50, which is controlled by a control signal from the control ECU 70, may, for example, increase its damping force when current is supplied from the control ECU 70 and decrease its damping force when the current supply is stopped. In this case, the variable damper 50 can switch between and apply two damping forces of different magnitudes. Note that the control method for the damping force of the variable damper 50 is not limited to switching between two damping forces of different magnitudes as described above.

[0038] Next, the operation of the suspension device 12 when a vehicle equipped with the vehicle seat 10 of this embodiment passes over a step formed in the road surface R will be described with reference to Figure 5.

[0039] Figure 5 is a schematic diagram illustrating the operation of the suspension system during vehicle travel. In Figure 5, the period from when the vehicle seat 10 is installed to when it reaches a step formed in the road surface R during travel, passes over the step, and when the vibration of the vehicle seat 10 stabilizes is shown in sections 1 to 8. Furthermore, in Figure 5, the state of the upper member 30, the variable damper 50, and the air spring 60 in each section is illustrated to make the extension and contraction states of the suspension system 12 easier to understand.

[0040] Section 1 in Figure 5 represents the period when the vehicle is traveling on a flat road surface R, and the vehicle seat 10 does not vibrate during this section. Section 8 in Figure 5 represents the period after the vibration of the vehicle seat 10 has stabilized, and, similar to section 1, the vehicle seat 10 does not vibrate.

[0041] Section 2 in Figure 5 is the period in which the vehicle's wheels 14, for example, the front wheels, are on a step. At this time, the lower acceleration sensor 25 detects an upward velocity (an example of a second predetermined velocity) caused by the force generated when the vehicle goes on a step (this force is sometimes called the "upward thrust force"). On the other hand, the upper acceleration sensor 35 also detects an upward velocity due to the aforementioned upward thrust force, similar to the lower acceleration sensor 25, but this velocity is smaller than the velocity detected by the lower acceleration sensor 25 due to the effects of the occupant's weight, the air spring 60 and the variable damper 50, etc. Therefore, in this section 2, an upward displacement occurs in the upper member 30, and a compressive force acts on the variable damper 50 as the upper member 30 approaches the lower member 20.

[0042] Section 3 in Figure 5 is the period in which the vehicle's wheels 14 reach the top of the step. At this time, the lower acceleration sensor 25 effectively stops detecting vertical velocity because the upward force no longer acts on it. On the other hand, the upper acceleration sensor 35 detects upward velocity in the same way as in section 2 because the upward force in section 2 acts with a delay via the air spring 60, etc. Therefore, in section 3, an upward displacement occurs in the upper member 30, and a force acts on the variable damper 50 in the direction of extension due to the upper member 30 separating from the lower member 20.

[0043] Section 4 in Figure 5 is the period during which the vehicle's wheels 14 return to their original height from the top of the step. During this time, the lower acceleration sensor 25 detects a downward velocity (an example of the first predetermined velocity) caused by the vehicle's descent. On the other hand, the upper acceleration sensor 35 also detects a downward velocity in conjunction with the vehicle's descent, similar to the lower acceleration sensor 25. However, this velocity is smaller than the velocity detected by the lower acceleration sensor 25 due to the effects of the air spring 60 and the variable damper 50. Therefore, in this section 4, a downward displacement occurs in the upper member 30, and an elongating force acts on the variable damper 50 as the upper member 30 separates from the lower member 20.

[0044] Sections 5 to 7 in Figure 5 represent the period from when the vehicle's wheels 14 overcome a step until the vibrations generated in the vehicle seat 10 stabilize. Specifically, in sections 5 to 7, the lower acceleration sensor 25 detects that the vertical velocity is virtually zero after overcoming the step. On the other hand, the upper acceleration sensor 35 detects a downward velocity in sections 5 and 7, and an upward velocity in section 6, due to the vibrations generated during the process of overcoming the step. Therefore, in sections 5 and 7, a downward displacement occurs in the upper member 30, and a compressive force acts on the variable damper 50 as the upper member 30 approaches the lower member 20. In section 6, an upward displacement occurs in the upper member 30, and an elongating force acts on the variable damper 50 as the upper member 30 moves away from the lower member 20. In Figure 5, graph L1 shows an example of vertical displacement of the upper member 30, and graph L2 shows an example of the transition of compressive or elongative force acting on the variable damper 50.

[0045] The suspension device 12 according to this embodiment aims to improve ride comfort by adjusting the damping force of the variable damper 50 during the series of operations described above, thereby suppressing vibrations felt by the occupants or shortening the period during which the vehicle seat 10 vibrates.

[0046] Specifically, in the suspension system 12, it is preferable to actively dampen the vibration of the vehicle seat 10 with the variable damper 50 when the vehicle is not going over or down a step, in other words, when the lower acceleration sensor 25 is not detecting a high speed (specifically, sections 3, 5-7, etc. in Figure 5). By actively damping vibrations in sections 3, 5-7, etc., the period during which the vehicle seat 10 vibrates can be shortened, and thus an improvement in ride comfort can be expected.

[0047] On the other hand, at the timing when going over or down a step, in other words, at the timing when the lower acceleration sensor 25 detects a large speed (specifically, sections 2 and 4 in Figure 5), it is not necessarily preferable for the damping force of the variable damper 50 to be high.

[0048] Specifically, as in the case of section 4 described above, when the vehicle descends a step, a downward displacement occurs in the upper member 30, and an elongating force acts on the variable damper 50, the damping force of the variable damper 50 acts to pull the upper member 30 downward. Since this effect increases in proportion to the damping force of the variable damper 50, if the damping force of the variable damper 50 is large, the occupant may feel that the seat body 11 has descended significantly, resulting in a poor ride. Therefore, in this embodiment, in cases such as section 4, the damping force of the variable damper 50 is reduced to decrease the force pulling the seat body 11 downward, thereby suppressing the deterioration of ride comfort.

[0049] Furthermore, as in the case of section 2 described above, when the vehicle drives over a step, an upward displacement occurs in the upper member 30, and a compressive force acts on the variable damper 50, the damping force of the variable damper 50 acts to push the upper member 30 upward. Therefore, in section 2, as in the case of section 4 described above, it is conceivable to lower the damping force of the variable damper 50 to reduce the upward force on the seat body 11. However, in section 2, a compressive force acts on the variable damper 50, and consequently, the upper member 30 and the lower member 20 move in a direction toward each other. In this case, if the upward force is large, there is a risk that the upper member 30 and the lower member 20 will come into contact (this phenomenon is sometimes called "bottoming out"). If the upper member 30 and the lower member 20 come into contact, the vibration absorption performance of the suspension device 12 will cease to function, and the ride comfort for the occupants will be significantly reduced.

[0050] Taking the above points into consideration, in this embodiment, when the vehicle falls within section 2, the damping force of the variable damper 50 is not uniformly reduced, but rather adjusted according to the detection results of the lower acceleration sensor 25 and / or the upper acceleration sensor 35 to improve ride comfort.

[0051] To achieve the control described above, the control ECU 70 of this embodiment operates the variable damper 50 in three control modes. Specifically, the control ECU 70 selectively executes a first control mode, which is performed when the upper acceleration sensor 35 detects a first predetermined downward speed and the lower acceleration sensor 25 detects a speed greater than the first predetermined downward speed; a second control mode, which is performed when the upper acceleration sensor 35 detects a second predetermined upward speed and the lower acceleration sensor 25 detects a speed greater than the second predetermined upward speed; and a third control mode, which is performed when the conditions for executing the first and second control modes are not met.

[0052] The first control mode is a mode in which the damping force of the variable damper 50 is reduced. More specifically, this mode is in which the variable damper 50 is in a state in which the damping force is kept low (hereinafter also referred to as the "first state") by, for example, not supplying a predetermined amount of power from the control ECU 70 to the variable damper 50.

[0053] The third control mode is a mode in which the damping force of the variable damper 50 is increased. More specifically, this mode is in which the variable damper 50 is set to a state in which the damping force is increased (hereinafter also referred to as the "second state") by supplying a predetermined power from the control ECU 70 to the variable damper 50. Here, "increasing the damping force" means increasing it compared to the damping force in the first control mode, and the specific value of the damping force is not particularly limited. In addition, in the third control mode, the damping force can also be varied (for example, based on skyhook control) between the maximum damping force that the variable damper 50 can take and the minimum damping force, according to the detection results of the lower acceleration sensor 25 and / or the upper acceleration sensor 35.

[0054] The second control mode adjusts the damping force of the variable damper according to the detection results of the lower acceleration sensor 25 and / or the upper acceleration sensor 35. In the second control mode, as in the third control mode, the damping force of the variable damper 50 can be varied from the maximum damping force to the minimum damping force it can take. However, the method for calculating the damping force in the second control mode is different from the method for calculating the damping force in the third control mode. In this embodiment, a predetermined threshold is set in advance, and if the speed detected by the lower acceleration sensor 25 (second predetermined speed) is slower than the set threshold, the variable damper 50 is set to the first state, and if it is the same as or faster than the threshold, the variable damper 50 is set to the second state. The threshold that is set in advance only needs to be set to a speed that can avoid bottoming out. The specific value of the threshold should be set considering the distance between the upper member 30 and the lower member 20, the elasticity of the air spring 60, etc. Furthermore, in this embodiment, the case in which the speed detected by the lower acceleration sensor 25 is compared with a threshold is illustrated as an example. However, instead, the speed detected by the upper acceleration sensor 35, or the speed detected by both the lower acceleration sensor 25 and the upper acceleration sensor 35, may be compared with the threshold.

[0055] Figure 6 shows an example of the control modes for each section shown in Figure 5. Each of the control modes described above can be applied to each section, as shown in Figure 6. Specifically, when traveling through section 2, the variable damper 50 should be operated in the second control mode; when traveling through sections 3 and 5-7, the variable damper 50 should be operated in the third control mode; and when traveling through section 4, the variable damper 50 should be operated in the first control mode. Note that when traveling through sections 1 and 8, no vibration occurs in the vehicle seat 10, so the control mode of the variable damper 50 is not particularly limited, but it can be operated in the second control mode, for example.

[0056] As described above, in the suspension device 12 and the vehicle seat 10 including the suspension device 12 according to this embodiment, vibrations can be effectively dampened by the variable damper 50. In addition, since the second control mode is executed in section 2, bottoming out can be avoided, and a good ride comfort for the occupants can be achieved.

[0057] In the above embodiment, a variable damper 50 is exemplified that switches the damping force in two stages depending on whether or not current is supplied. However, a variable damper 50 that can switch between three or more stages by adjusting the supplied current can also be used. More specifically, for example, a variable damper 50 can be used that can operate in one of the following states: a first state with low damping force and a second state with high damping force, as well as a third state in which it operates with a damping force between the damping force in the first state and the damping force in the second state. In this case, the control ECU 70 should adopt the third state as the second control mode. In the second control mode, if the variable damper 50 is operated with the third state, that is, with a damping force between the damping force in the first state and the damping force in the second state, bottoming out can be suppressed while stabilizing the vibration of the vehicle seat 10 in a shorter time.

[0058] In addition to the above example, the damping force in the third state described above may be a specific value, but it may also be adjustable in steps according to the detection results of the lower acceleration sensor 25 and / or the upper acceleration sensor 35. As mentioned above, if the damping force can be adjusted in the second control mode, bottoming out can be suppressed more reliably. Similarly, if the damping force can be adjusted in the third control mode, the damping force based on the known skyhook control can be generated with even greater precision.

[0059] Furthermore, in the embodiment described above, as shown in Figure 6, an example was given in which three control modes, the first to the third control modes, are adopted as the normal control modes executed by the control ECU 70. However, there may be two such normal control modes, as illustrated below.

[0060] Figure 7 shows a list of other examples of control modes in each section shown in Figure 5. In the control ECU for the suspension device according to a modified embodiment described above, a fourth control mode is employed instead of the second and third control modes described above, as shown in Figure 7. The fourth control mode is executed when the conditions for executing the first control mode are not met, and may be a mode that increases the damping force of the variable damper 50. In this context, "increasing" refers to the second or third state described above.

[0061] The suspension device according to the above-described modification selectively executes the first control mode and the fourth control mode based on the detection results of the upper acceleration sensor 35 and the lower acceleration sensor 25. Therefore, when traveling through section 2 shown in Figure 5, the fourth control mode is executed, which increases the damping force of the variable damper 50, thereby more reliably suppressing bottoming out and improving ride comfort.

[0062] (Bottoming-out prevention control mode) Incidentally, depending on the height of the step the vehicle goes over and the speed at which it goes over the step, the aforementioned upward force may increase further, and it is conceivable that bottoming out cannot be avoided in the normal control mode employing three modes, the first to third control modes, and the normal control mode employing two modes, the first and fourth control modes. Therefore, in this embodiment, when it is anticipated that the upward force will exceed a predetermined threshold, the control ECU 70 is configured to execute a bottoming-out prevention control mode in which the damping force of the variable damper 50 is adjusted to the maximum damping force.

[0063] Figure 8 is a graph showing the relationship between time and the vertical velocity of the seat body 11, with the horizontal axis representing time and the vertical axis representing the vertical velocity of the seat body 11. In Figure 8, the waveform is shown when a vehicle equipped with the vehicle seat 10 travels through section A at time t1, section B at time t2, and section C at time t3. Figure 9 is a graph showing the relationship between time and the damping force of the variable damper 50, with the horizontal axis representing time and the vertical axis representing the damping force of the variable damper 50.

[0064] As shown in Figure 8, when the vehicle is traveling through sections A and C, the upward force is below a defined threshold, while when the vehicle is traveling through section B, the upward force temporarily exceeds the defined threshold. In other words, when the vehicle is traveling through sections A and C, the upward speed detected by the lower acceleration sensor 25 is below a defined reference speed, while when the vehicle is traveling through section B, the upward speed detected by the lower acceleration sensor 25 temporarily exceeds the defined reference speed.

[0065] As shown in Figures 8 and 9, when the vehicle is traveling through section A, the control ECU 70 is running in normal control mode. This allows the variable damper 50 to effectively dampen vibrations and prevent bottoming out, resulting in a comfortable ride for the occupants when the vehicle is traveling through section A. Alternatively, the normal control mode may be executed based on the speed detected by the upper acceleration sensor 35. Or, the normal control mode may be executed based on both the speed detected by the upper acceleration sensor 35 and the speed detected by the lower acceleration sensor 25.

[0066] Furthermore, as the vehicle travels through section B, if the upward speed detected by the lower acceleration sensor 25 temporarily exceeds a predetermined reference speed, the control ECU 70 executes a bottoming-out prevention control mode. This adjusts the damping force of the variable damper 50 to its maximum damping force. This prevents bottoming out when the upward speed detected by the lower acceleration sensor 25 (the speed at which the lower acceleration sensor 25 moves upward) exceeds the reference speed. As a result, deterioration of the occupant's ride comfort due to bottoming out can be suppressed.

[0067] Here, the control ECU 70 can also execute the bottoming-out prevention control mode for a predetermined time when the upward speed detected by the lower acceleration sensor 25 exceeds a predetermined reference speed. For example, the bottoming-out prevention control mode can be executed for 3 seconds when the upward speed detected by the lower acceleration sensor 25 exceeds a predetermined reference speed. Alternatively, the control ECU 70 can be configured to execute the bottoming-out prevention control mode for a predetermined time each time it detects that the upward speed detected by the lower acceleration sensor 25 has exceeded a predetermined reference speed. For example, if it is decided to execute the bottoming-out prevention control mode for 3 seconds when the upward speed detected by the lower acceleration sensor 25 exceeds a predetermined reference speed, and then 2 seconds later the upward speed detected by the lower acceleration sensor 25 exceeds the predetermined reference speed again, it is decided to execute the bottoming-out prevention control mode for 3 seconds from this decision. In this case, the prevention mode will be executed for 5 seconds. This control prevents bottoming out within the specified time frame. The bottoming-out prevention control mode can also be configured to be executed based on the speed detected by the upper acceleration sensor 35. Furthermore, the bottoming-out prevention control mode can be configured to be executed based on both the speed detected by the upper acceleration sensor 35 and the speed detected by the lower acceleration sensor 25. Additionally, the duration of the bottoming-out prevention control mode can be extended according to the amount of overshoot relative to the reference speed.

[0068] When the vehicle is traveling through section C, the upward speed detected by the lower acceleration sensor 25 is below a predetermined reference speed. Therefore, the control ECU 70 executes the normal control mode. However, when switching from the bottoming-out prevention control mode to the normal control mode, the damping force of the variable damper 50 changes abruptly, which may cause a feeling of discomfort regarding the change in ride comfort. Therefore, the system can also execute the recovery control mode described below.

[0069] As shown in Figure 9, after executing the bottoming-out prevention control mode, the control ECU 70 executes a recovery control mode for a predetermined time t4 to adjust the damping force of the variable damper 50 so that the damping force of the variable damper 50 gradually approaches the damping force of the variable damper 50 in the normal control mode, and then executes the normal control mode. In this way, by executing the recovery control mode before executing the normal control mode, it is possible to suppress the unnatural feeling of change in ride comfort caused by a sudden change in the damping force of the variable damper 50.

[0070] (Controls that take into account short stature of the crew) Incidentally, when an occupant shorter than average sits in the vehicle seat 10, that occupant tends to sit with the seat body 11 set to a lower height. Setting the seat body 11 to a lower height can restrict the stroke of the variable damper 50, making bottoming out more likely. The control of the control unit when the seat body 11 is set lower than the predetermined position will be described below.

[0071] Figure 10 is a graph showing the relationship between time and the damping force of the variable damper 50 when driving on the same road surface under the same conditions. The horizontal axis represents time, and the vertical axis represents the damping force of the variable damper 50. In this graph, the waveform indicated by the symbol H2 is the waveform when the height position of the seat body 11 is set to a height above a predetermined position, and the waveform indicated by the symbol H1 is the waveform when the height position of the seat body 11 is set to a height below a predetermined position. As shown in this figure, when the control ECU 70 detects that the height position of the seat body 11 is set to a height below a predetermined position, the control ECU 70 executes the bottoming-out prevention control mode earlier than when the height position of the seat body 11 is set to a height above a predetermined position. This effectively suppresses the occurrence of bottoming out when the height position is set to a height below a predetermined position.

[0072] This disclosure is not limited to the embodiments described above, and can be implemented with various modifications without departing from the spirit of this disclosure. All such modifications are included in the technical concept of this disclosure. [Explanation of symbols]

[0073] 10 Vehicle seats 11 Seat Body 12 Suspension System 13. Floor of the vehicle 20 Lower Member 25. Lower-side acceleration sensor (an example of the first sensor) 30 Upper Member 35. Upper-side acceleration sensor (an example of a second sensor) 40 X-link (an example of a lifting mechanism) 50 Variable-Character Damper 60. Air spring (an example of a spring) 70 Control ECU (Example of a control device)

Claims

1. A lower member fixed to the floor of the vehicle body, An upper member is positioned above the lower member and to which the seat body is connected, A lifting mechanism that connects the upper member to the lower member so that it can move up and down, A spring that deforms elastically as the upper member moves up and down, A variable damper with adjustable damping force is provided between the lower member and the upper member, A first sensor for detecting the vertical velocity of the upper member, A second sensor for detecting the vertical velocity of the lower member, The system includes a control device capable of controlling the damping force of the variable-characteristic damper based on the detection result of at least one of the first sensor and the second sensor, The control device is When the first sensor or the second sensor detects that the speed moving upward or downward is below a predetermined reference speed, a normal control mode is provided in which the damping force of the variable damper is adjusted to reduce the vertical speed of the upper member relative to the lower member in a shorter time than when the damping force of the variable damper is set to a constant damping force, and to avoid bottoming out where the upper member and the lower member come into contact. When the first sensor or the second sensor detects that the speed moving upward or downward exceeds the reference speed, a bottoming-out prevention control mode is provided which adjusts the damping force of the variable damper to the maximum damping force. A suspension system for a vehicle seat that selectively performs the following actions.

2. The suspension device for a vehicle seat according to claim 1, wherein the control device executes the bottoming-out prevention control mode for a predetermined time when the speed at which the second sensor moves upward exceeds the reference speed.

3. The suspension device for a vehicle seat according to claim 2, wherein the control device executes the bottoming-out prevention control mode for a predetermined time each time the speed at which the second sensor moves upward exceeds the reference speed.

4. The suspension device for a vehicle seat according to claim 1, wherein the control device, after executing the bottoming prevention control mode, executes a return control mode in which it adjusts the damping force of the variable characteristic damper so that the damping force of the variable characteristic damper gradually approaches the damping force of the variable characteristic damper in the normal control mode, and then executes the normal control mode.

5. The seat itself in which the occupant sits, The vehicle seat suspension device according to claim 1, wherein the seat body is connected to the upper member, Vehicle seats.

Images