Patent Publication Number: US-2022212746-A1

Title: Straddle type vehicle and control device

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application is a continuation of International Patent Application No. PCT/JP2020/034632 filed on Sep. 14, 2020, which claims priority to and the benefit of Japanese Patent Application No. 2019-177709 filed on Sep. 27, 2019, the entire disclosures of which are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a straddle type vehicle and a control device. 
     Description of the Related Art 
     A straddle type vehicle provided with a steering damper is known. International Publication No. 2013/168422 discloses a technique for suppressing a vibration of a steering mechanism by controlling a damping force of a steering damper, based on a state of a vehicle, such as a load applied to a front wheel and a steering angle of the steering mechanism. 
     SUMMARY OF THE INVENTION 
     According to an embodiment of the present invention, there is provided a straddle type vehicle comprising:
         a steering mechanism configured to steer a front wheel;   a steering damper device capable of variably generating a damping force working on a rotating action of the steering mechanism; and   a control unit configured to control the damping force of the steering damper device, wherein   the control unit controls the damping force, based on a change amount per unit time of steering torque generated in the steering mechanism and a deceleration of the front wheel.       

     Also, according to another embodiment of the present invention, there is provided a control device to be applied to a straddle type vehicle, the straddle type vehicle including a steering mechanism that steers a front wheel and a steering damper device capable of variably generating a damping force working on a rotating action of the steering mechanism, the control device being configured to control the damping force of the steering damper device, wherein
         the control device controls the damping force, based on a change amount per unit time of steering torque generated in the steering mechanism and a deceleration of the front wheel.       

    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view of a vehicle according to one embodiment. 
         FIG. 2  is a front view of the vehicle of  FIG. 1 . 
         FIG. 3  is a schematic view illustrating a configuration of a steering damper device according to one embodiment. 
         FIG. 4  is a block diagram illustrating an example of a control configuration of the straddle type vehicle according to one embodiment. 
         FIG. 5  is a flowchart illustrating a process example of a control unit according to one embodiment. 
         FIG. 6  is a flowchart illustrating a process example of the control unit according to one embodiment. 
         FIG. 7  is a flowchart illustrating a process example of the control unit according to one embodiment. 
         FIG. 8  is a diagram illustrating an example of a table indicating a relationship between a deceleration and a bank angle of a front wheel, and an estimated value of steering torque. 
         FIG. 9  is a block diagram illustrating an example of a control configuration of the straddle type vehicle according to one embodiment. 
         FIG. 10  is a flowchart illustrating a process example of the control unit according to one embodiment. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     In the straddle type vehicle, incidentally, when the brake is applied while turning, the steering mechanism may oscillate in some cases, and there is a demand for suppressing such an oscillation. 
     An embodiment of the present invention provides a technique for suppressing an oscillation of a steering mechanism at the time of braking while turning. 
     Hereinafter, embodiments will be described in detail with reference to the attached drawings. Note, the following embodiments are not intended to limit the scope of the claimed invention, and limitation is not made to an invention that requires a combination of all features described in the embodiments. Two or more of the multiple features described in the embodiments may be combined as appropriate. Furthermore, the same reference numerals are given to the same or similar configurations, and redundant description thereof is omitted. 
     In addition, in each drawing, arrows X and Y indicate horizontal directions orthogonal to each other, and an arrow Z indicates a vertical direction. In the following description, the traveling direction of the vehicle is defined as X direction, which is set to a front-and-rear direction, and the front and the rear are defined. In addition, a vehicle width direction of the vehicle is defined as Y direction, which is set to a left-and-right direction with a forward direction of the vehicle as a reference, and the left and the right are defined. 
     First Embodiment 
     Outline of Straddle Type Vehicle 
       FIG. 1  is a side view (a right side view) of a straddle type vehicle  100  according to one embodiment, and  FIG. 2  is a front view of the vehicle  100 , illustrating an outline of the vehicle  100 .  FIGS. 1 and 2  respectively illustrate a side view and a front view in a state in which the vehicle  100  stands in a vertical posture. For the vehicle  100  in the present embodiment, a motorcycle including a front wheel  101  and a rear wheel  102  is given as an example, but the present invention is also applicable to any other type of the straddle type vehicle. 
     The vehicle  100  includes a vehicle body frame  103  forming its backbone. A power unit  104  that drives the rear wheel  102  is supported at the vehicle body frame  103 . The power unit  104  includes an engine  104   a  (for example, a multi-cylinder four-cycle engine) and a transmission  104   b  that changes an output from the engine  104   a,  and the output from the transmission  104   b  is transmitted by a chain transmission mechanism to the rear wheel  102 . 
     A seat frame  103   a  that supports a seat  108  on which the rider is seated is coupled with a rear portion of the vehicle body frame  103 . A swing arm  109  is swingably supported by the rear portion of the vehicle body frame  103 , and the rear wheel  102  is rotatably supported by the swing arm  109 . 
     A head pipe is provided in a front portion of the vehicle body frame  103 . The head pipe rotatably supports a steering mechanism  10 . 
     The steering mechanism  10  steers the front wheel  101 , and includes a pair of front forks  11 , a top bridge  12 , a bottom bridge  13 , and left and right handlebars  14 . The pair of front forks  11  are rotatably supported by the head pipe. The pair of front forks  11  are coupled at upper end portions by the top bridge  12 , and are coupled by the bottom bridge  13  below the top bridge  12 . A steering stem (not illustrated) is attached to extend between the top bridge  12  and the bottom bridge  13 , and the steering stem is rotatably attached in the head pipe. 
     In upper portions of the pair of front forks  11 , separate-type left and right handlebars  14  for steering the front wheel  101  are provided, and the handlebars  14  are each provided with a grip  14   a  to be gripped by the rider. The left and right handlebars  14  are disposed to be inclined downward toward the outside in the vehicle width direction in a vehicle front view, and are disposed for the rider to easily get on the vehicle in a forward inclined posture. 
     The vehicle  100  includes braking devices  112  and  113 . The braking device  112  is a braking device for the front wheel  101 , and includes a brake disc  112   a  provided on the front wheel  101  and a brake caliper  112   b  supported by the front fork  11 . The right handlebar  14  is provided with a brake lever  114   a  for operating the brake caliper  112   b.  The left handlebar  14  is provided with a clutch lever  114   b  for operating the clutch of the transmission  104   b.    
     The braking device  113  is a braking device for the rear wheel  102 , and includes a brake disc  113   a  provided on the rear wheel  102  and a brake caliper  113   b  supported by the swing arm  109 . A brake pedal  115  for operating the brake caliper  113   b  is provided on a right side portion of the vehicle  100 . Steps  116  on which the rider places its legs are respectively provided on the left and the right side portions of the vehicle  100 . A brake pedal  115  is disposed near the step  116  on the right side, and a shift pedal, not illustrated, is disposed near the step  116  on the left side. 
     Configuration of Steering Damper 
       FIG. 3  is a schematic view illustrating a configuration of a steering damper device  20 . The steering damper device  20  is a device capable of variably generating the damping force working on a rotating action of the steering mechanism  10 . For example, in order to reduce a so-called kickback (reaction) that is a sudden oscillation of the handlebars  14 , when an external force from the road surface during traveling works on the front wheel  101 , the steering damper device  20  generates the damping force against the oscillation. 
     In the present embodiment, the steering damper device  20  is an electronically controlled steering damper, and is capable of variably controlling the damping force by controlling the drive current of a solenoid valve  21 . 
     The steering damper device  20  is a hydraulic rotary type in which a swingable vane  23  is disposed in an oil chamber  22  having a fan shape in a plan view, and uses, as the damping force, a flow resistance of hydraulic oil in the oil chamber  22  generated when the vane  23  swings. The top bridge  12  is coupled through a link mechanism  24  with a base portion of the vane  23 . 
     The steering damper device  20  includes a hydraulic control circuit  25 . The hydraulic control circuit  25  includes the solenoid valve  21 . The solenoid valve  21  is driven by a control unit  50  to be described later. The control unit  50  drives the solenoid valve  21  to change the opening area of the valve and change the flow resistance of the hydraulic oil. That is, the control unit  50  controls the drive current of the solenoid valve  21  to control the damping force generated by the steering damper device  20 . The hydraulic control circuit  25  also includes a check valve  26 , a relief valve  27 , and an accumulator  28 . Solid arrows in the drawing each indicate a flow of the hydraulic oil when the steering mechanism  10  makes a turn to the left. Furthermore, dotted arrows in the drawing each indicate a flow of the hydraulic oil when the steering mechanism  10  makes a turn to the right. 
     Note that, in the present embodiment, the configuration of the steering damper device  20  is given as an example, and any other known configuration is adoptable. For example, the steering damper device  20  may be a cylinder type. 
     Control Configuration 
       FIG. 4  is a block diagram illustrating an example of a control configuration of the vehicle  100 .  FIG. 4  mainly illustrates a configuration necessary in relation to the present embodiment to be described later. 
     The vehicle  100  includes the control unit  50  configured with an electric control unit (ECU) or the like. The control unit  50  includes a processing unit  51 , a storage unit  52  such as a RAM and a ROM, and an interface unit  53  (I/F unit) that relays transmission and reception of signals between an external device and the processing unit  51 . The processing unit  51  is a processor represented by a CPU, and executes a program stored in the storage unit  52 . In the storage unit  52 , data and the like used by the processing unit  51  for processing, in addition to the program executed by the processing unit  51 , are stored. 
     In the present embodiment, the control unit  50  controls the damping force of the steering damper device  20 . More specifically speaking, the control unit  50  controls the damping force of the steering damper device  20  when a vehicle  100  is braking while turning. 
     Note that the control unit  50  may include a plurality of electric control units (ECUs), and each of them may include a processor, a storage device, and an external FF. For example, the control unit  50  may include a drive controlling ECU that controls driving of the power unit  104  and a damping force controlling ECU that controls the damping force of the steering damper device  20 . Note that the number of ECUs and the functions assigned to the respective ECUs can be designed as appropriate, and can be subdivided or integrated as compared with the above example. 
     The vehicle  100  includes a front wheel rotation speed sensor  101   a  that detects the rotation speed of a front wheel  101 . 
     An inertial measurement unit (IMU)  30  is a sensor unit that detects a behavior of the vehicle  100 , and is disposed, for example, near the center of gravity of the vehicle  100 . In the case of the present embodiment, the IMU  30  includes acceleration sensors  30   a  to  30   c  that respectively detect accelerations in a front-and-rear direction, a left-and-right direction, and a vertical direction of the vehicle  100 , and respective angular velocity sensors  30   d  to  30   f  that detect the respective angular velocities in a roll direction, a pitch direction, and a yaw direction of the vehicle  100 . 
     Process Example of Control Unit 
     A process example of the control unit  50  will be described.  FIGS. 5 to 7  are flowcharts each illustrating an example of a process performed by the control unit  50 .  FIG. 5  is an example of damping force control, of the steering damper device  20  at the time of braking while turning, to be conducted by the control unit  50 . Note that the magnitude of the damping force at the start of the present process is set to an initial value, and such an initial value can be appropriately set, based on the configuration or the like of the vehicle  100  or the steering damper device  20 . 
     In S 1 , the control unit  50  acquires a change amount ΔTrq/Δt per unit time of steering torque Trq. Details will be described later (see  FIG. 6 ). 
     In S 2 , the control unit  50  acquires deceleration a (m/s 2 ) of the front wheel  101 . For example, the control unit  50  acquires the deceleration a, based on a detection result of the front wheel rotation speed sensor  101   a.  As an example, the control unit  50  calculates (in other words, differentiates) a change amount per unit time of the rotation speed of the front wheel  101  that has been detected by the front wheel rotation speed sensor  101   a,  and acquires the deceleration a. 
     In S 3 , the control unit  50  conducts the damping force control of the steering damper device  20 . The control unit  50  determines the damping force based on the change amount ΔTrq/Δt acquired in S 1 , the deceleration a acquired in S 2 , and the like, and controls the damping force of the steering damper device  20  such that the steering damper device  20  generates its damping force. That is, the control unit  50  controls the damping force based on the change amount ΔTrq/Δt acquired in S 1 , the value of the deceleration a acquired in S 2 , and the like. In the present embodiment, the control unit  50  controls the drive current of the solenoid valve  21  so that the steering damper device  20  generates a desired damping force. Details will be described later (see  FIG. 7 ). 
       FIG. 6  is a flowchart illustrating a detailed example of a process of acquiring the steering torque Trq in S 1  of  FIG. 5 . In S 11 , the control unit  50  acquires the deceleration a of the front wheel  101 . The control unit  50  acquires the deceleration a, for example, in a process similar to the process of S 2 . 
     In S 12 , the control unit  50  acquires a bank angle (roll angle) θ of the vehicle  100 . For example, the control unit  50  integrates a detection result (roll angular velocity) of the angular velocity sensor  30   d  in the roll direction, and acquires the bank angle θ. 
     In S 13 , the control unit  50  acquires the steering torque Trq. In the present embodiment, the control unit  50  estimates the steering torque Trq, based on the deceleration a acquired in S 11  and the bank angle θ acquired in S 12 .  FIG. 8  is a diagram illustrating an example of a table illustrating a relationship between the deceleration a and the bank angle θ of the front wheel  101 , and the estimated value of the steering torque Trq. The control unit  50  refers to this table, and estimates the steering torque Trq, based on the deceleration a and the bank angle θ. 
     In the present embodiment, the estimated value of the steering torque Trq is set to be larger, as the roll angle (bank angle) becomes larger. In addition, in the case of the present embodiment, the deceleration has a magnitude relationship of A5&gt;A4&gt;A3&gt;A2&gt;A1, and the estimated value of the steering torque Trq is set to be larger, as the deceleration a becomes larger. 
     From one point of view, it can be said that the control unit  50  is capable of grasping a brake state of the vehicle  100  from the deceleration a, and is capable of grasping the turning state of the vehicle from the bank angle. Therefore, it can be said that the control unit  50  estimates the steering torque Trq based on the deceleration a and the bank angle θ to estimate the steering torque Trq in accordance with the vehicle state at the time of braking while turning. 
     Note that as a method for acquiring the steering torque Trq, another method is adoptable. For example, the control unit  50  may calculate the steering torque Trq based on various parameters. As an example, the control unit  50  may calculate the steering torque Trq, based on parameters such as a vehicle weight, the deceleration a, the roll angle θ, a front wheel assigned load, and a ground point lateral movement amount. 
     In S 14 , the control unit  50  acquires the change amount ΔTrq/Δt per unit time of the steering torque Trq. In the present embodiment, the control unit  50  acquires the change amount ΔTrq/Δt based on the steering torque Trq acquired in S 13 . For example, the control unit  50  stores the value of the steering torque Trq acquired in a previous process, and divides the change amount of the steering torque from the previous process time to the current process time by the control cycle to calculate the change amount ΔTrq/Δt. Note that in the case of a first control cycle, the control unit  50  may calculate a change amount from a predetermined initial value, or may output θ as the change amount. 
       FIG. 7  is a flowchart illustrating a detailed example of the process of the damping force control in S 3  of  FIG. 5 . In S 31 , the control unit  50  sets a target current value I of the solenoid valve  21  to generate a desired damping force, based on the change amount ΔTrq/Δt acquired in S 1  and the deceleration a acquired in S 2 . 
     As an example, the control unit  50  may set the target current value I so that the damping force increases, as the change amount ΔTrq/Δt becomes larger. In a case where the damping force is made too large when the change amount ΔTrq/Δt is small, the rider may feel strange in some cases. This may affect the riding feeling in some cases. On the other hand, in a case where the change amount ΔTrq/Δt is large, the rider may not be able to handle a sudden inclination caused by the steering mechanism at the time of turning, in some cases. Therefore, the control unit  50  may set the target current value I so that the damping force increases, as the change amount ΔTrq/Δt becomes larger. By increasing the damping force, as the change amount ΔTrq/Δt becomes larger, it is possible to prevent the rider from feeling strange due to the generation of the damping force more than necessary, and it is possible to generate a larger damping force for a sudden inclination that the rider cannot handle or that is difficult to handle. 
     In addition, the control unit  50  may set the target current value I so that the damping force increases, as the deceleration a becomes larger. It is considered that the vehicle  100  is more likely to slip, as the deceleration a becomes larger. By controlling the damping force based on the deceleration a, an occurrence of slip can be suppressed. 
     Furthermore, the control unit  50  may control the damping force based on the product of the change amount ΔTrq/Δt and the deceleration a (that is, set the target current value I). The slip at the time of braking while turning is likely to occur, when the deceleration a is large and the change amount ΔTrq/Δt is large. By controlling the damping force, based on the product of the change amount ΔTrq/Δt and the deceleration a, it is possible to control the damping force in accordance with the ease of slipping, and it is possible to further suppress the occurrence of slip of the vehicle  100 . 
     In S 32 , the control unit  50  checks whether the traveling speed of the vehicle  100  is equal to or higher than a threshold. The control unit  50  proceeds to S 33  in a case where the traveling speed is equal to or higher than the threshold, and proceeds to the process of S 35  in a case where the traveling speed is lower than the threshold. For example, the control unit  50  acquires the traveling speed of the vehicle  100 , based on the detection result of the front wheel rotation speed sensor  101   a,  and checks whether the traveling speed is equal to or higher than the threshold. 
     In S 33 , the control unit  50  sets the target current value I in consideration of the traveling speed of the vehicle  100 . For example, the control unit  50  may set the target current value I to further suppress an increase of the damping force, as the vehicle body speed of the vehicle  100  becomes faster. When the vehicle body speed of the vehicle  100  is high, the deceleration a tends to increase due to a disturbance such as an engine brake or a centrifugal force. Therefore, in a case where the damping force is determined based on the deceleration a, the damping force may become large more than necessary, in some cases. Therefore, by further suppressing an increase in the damping force, as the vehicle body speed of the vehicle  100  becomes higher, it is possible to suppress the oscillation of the steering mechanism  10  in a more effective manner in accordance with the vehicle speed. As an example, the control unit may determine the target current value I in consideration of the traveling speed, based on the table indicating the relationship between the target current value I set in S 31  and the target current value I in consideration of the traveling speed. In addition, for example, the control unit  50  may multiply the target current value I set in S 31  by a coefficient corresponding to the traveling speed to determine the target current value I. 
     In S 34 , the control unit  50  determines whether to be capable of conducting the damping force control, based on a detection result of the IMU  30 . In a case of determining that the control can be conducted, the control unit  50  proceeds to the process of S 36 , whereas in a case of determining that the control cannot be conducted, the control unit  50  proceeds to the process of S 35 . For example, it is conceivable that the control unit  50  makes an erroneous determination regarding the deceleration a, due to erroneous detection, a failure, or the like of the front wheel rotation speed sensor  101   a.  In this case, it is conceivable that the control unit  50  will increase the damping force in an unnecessary situation. Hence, by increasing the damping force only when the vehicle  100  is actually decelerating in accordance with the detection result of the IMU  30 , the control unit  50  is capable of suppressing an influence on the riding feeling due to an unnecessary control intervention. For example, the control unit  50  may determine whether to be capable of conducting the control, based on the detection result of the acceleration sensor  30   a  in the front-and-rear direction or the like. 
     In S 35 , the control unit  50  sets the target current value Ito an initial value. That is, in a case where the traveling speed of the vehicle  100  does not reach a threshold, or in a case where the IMU  30  cannot detect that the vehicle  100  is actually decelerating, the target current value I is set to the initial value. This enables prevention of an unnecessary control intervention, and reduces the rider&#39;s strange feeling. 
     In S 36 , the control unit  50  drives the solenoid valve  21  with the target current value I that has been set. That is, the control unit  50  drives the solenoid valve  21  to control the damping force of the steering damper device  20 . 
     As described heretofore, according to the present embodiment, the damping force of the steering damper device  20  is controlled, based on the change amount ΔTrq/Δt per unit time of the steering torque Trq generated in the steering mechanism  10  and the deceleration a of the front wheel  101 . Therefore, it is possible to suppress the oscillation of the steering mechanism  10  in accordance with a vehicle state at the time of braking while turning. More specifically speaking, the damping force is controlled in a more effective manner in accordance with a vehicle body situation. Therefore, it is possible to suppress the oscillation of the steering mechanism  10  at the time of braking while turning, while reducing the strange feeling of the rider due to an unnecessary increase in the damping force. 
     Note that in setting the target current value I of the solenoid valve  21 , the control unit  50  may decrease the target current value I at a constant rate, in a case where the target current value I decreases. In other words, in setting the target current value I of the solenoid valve  21 , the control unit  50  is also capable of adopting a configuration of applying a rate limit to a downstream side. In the present embodiment, the damping force is generated against a sudden rise of the steering torque Trq to suppress the oscillation of the steering mechanism  10 . Therefore, responsiveness when the damping force increases (at the rising time) is important. However, in a case where the damping force is lowered as soon as a high damping force is no longer needed, the effect of the control may be weakened, or the rider may feel strange, in some cases. Therefore, by gradually reducing the damping force that has been generated, it is possible to suppress the oscillation of the steering mechanism  10  in a more effective manner. 
     In addition, the present embodiment has been described by focusing on the damping force control (for convenience, the damping force control for the time of braking while turning) of the steering damper device  20  at the time of braking while turning. However, the control unit  50  may conduct another type of the damping force control of the steering damper device  20  in parallel, in accordance with the traveling state of the vehicle  100 . 
     As an example, the control unit  50  may conduct the damping force control (for convenience, referred to as damping force control for the time of normal traveling) of the steering damper device  20  based on the vehicle body speed, the acceleration, or the like. For example, the control unit  50 , in the normal traveling, while controlling the damping force of the steering damper device  20  in accordance with the damping force control for the time of normal traveling, may allow the damping force control for the time of braking while turning to intervene at the time of braking while turning. For example, the control unit  50  may compare the desired damping force based on the damping force control for the time of normal traveling with the desired damping force based on the damping force control for the time of braking while turning, and may set the maximum value of them as a final output of the damping force. More specifically speaking, the control unit  50  may compare the target current value I of the solenoid valve  21  based on the damping force control for the time of normal traveling with the target current value I of the solenoid valve  21  based on the damping force control for the time of braking while turning, and may select the maximum value of them. 
     Other Embodiments 
       FIG. 9  is a block diagram illustrating an example of a control configuration of the vehicle  100  according to another embodiment. The present embodiment is different from the above embodiment in that the vehicle  100  includes a steering torque sensor  10   a.  In the following description, the same components as those of the above-described embodiment are denoted by the same reference numerals, and the descriptions will be omitted. 
     The steering torque sensor  10   a  detects torque generated in the steering mechanism  10 . As the steering torque sensor  10   a,  a known configuration such as a magnetostrictive torque sensor or a strain gauge torque sensor is adoptable. 
       FIG. 10  is a flowchart illustrating an example of the damping force control of the steering damper device  20  according to another embodiment, and illustrates a detailed example of the process of Si in  FIG. 5 , in a case where the steering torque is acquired, based on a detection result of the steering torque sensor  10   a.    
     In S 111 , the control unit  50  acquires the steering torque Trq, based on the detection result of the steering torque sensor  10   a.  S 112  is similar to the process of S 14  in  FIG. 6 . According to the present embodiment, the steering torque Trq generated in the steering mechanism  10  can be directly acquired as a measured value instead of an estimated value. 
     In addition, in the above embodiments, the power unit  104  is an engine. However, a configuration including an electric motor as the power unit  104  or a configuration including both an internal combustion engine and an electric motor is also adoptable. That is, the vehicle  100  may be an electric vehicle or a hybrid vehicle. 
     Summary of Embodiments 
     The above-described embodiments disclose at least a straddle type vehicle and a control device to be described as follows. 
     1. A straddle type vehicle ( 1 ) of the above embodiments comprises: 
     a steering mechanism ( 1 ) configured to steer a front wheel; 
     a steering damper device ( 20 ) capable of variably generating a damping force working on a rotating action of the steering mechanism; and 
     a control unit ( 50 ) configured to control the damping force of the steering damper device, wherein 
     the control unit controls the damping force, based on a change amount per unit time of steering torque generated in the steering mechanism and a deceleration of the front wheel (S 1 , S 2 , S 3 ). 
     According to this embodiment, the damping force is controlled, based on a change amount per unit time of the steering torque generated in the steering mechanism and the deceleration of the front wheel. Therefore, it is possible to suppress the oscillation of the steering mechanism at the time of braking while turning in accordance with the vehicle state at the time of braking while turning. 
     2. In the above embodiments, the control unit controls the damping force such that the damping force increases, as the change amount is increased (S 31 ). 
     According to this embodiment, it is possible to generate a larger damping force for a sudden inclination caused by the steering mechanism that the rider is not able to handle, and it is possible to suppress the vibration of the steering mechanism in a more effective manner. 
     3. In the above embodiments, the control unit controls the damping force such that the damping force increases, as the deceleration is increased (S 31 ). 
     According to this embodiment, the damping force becomes larger, in a state in which the deceleration is large and the vehicle is more likely to slip. Therefore, it is possible to suppress an occurrence of slip in a more effective manner. 
     4. In the above embodiments, the control unit controls the damping force, based on a product of the change amount and the deceleration (S 31 ). 
     According to this embodiment, the damping force is controlled in accordance with the likelihood of the occurrence of slip at the time of braking while turning. Therefore, it is possible to suppress the occurrence of slip in a more effective manner. 
     5. In the above embodiments, the control unit estimates the steering torque, based on a roll angle of the straddle type vehicle and the deceleration of the front wheel (S 11 , S 12 , S 13 ). 
     According to this embodiment, the steering torque can be estimated in accordance with the vehicle state at the time of braking while turning. 
     6. In the above embodiments, the straddle type vehicle further comprises 
     a torque sensor ( 10   a ) configured to detect magnitude of the steering torque generated in the steering mechanism, wherein 
     the control unit acquires the steering torque, based on a detection result of the torque sensor (S 111 ). 
     According to this embodiment, the magnitude of the steering torque is directly acquirable. 
     7. In the above embodiments, the straddle type vehicle further comprises 
     a detection unit ( 101   a ) configured to detect a rotation speed of the front wheel, wherein 
     the control unit acquires the deceleration of the front wheel, based on a detection result of the detection unit (S 2 , S 11 ). 
     According to this embodiment, the deceleration of the front wheel is acquirable from the rotation speed of the front wheel. 
     8. In the above embodiments, in a case where a vehicle body speed of the straddle type vehicle is equal to or higher than a threshold, the control unit controls the damping force, based on the change amount and the deceleration (S 32 ). 
     According to this embodiment, it is possible to avoid an unnecessary increase in the damping force, in a case where the vehicle body speed is lower than the threshold. 
     9. In the above embodiments, in controlling the damping force based on the change amount and the deceleration, the control unit suppresses an increase in the damping force, as a vehicle body speed of the straddle type vehicle increases (S 33 ). 
     According to this embodiment, by suppressing an increase in the damping force at the time of traveling at high speeds, while the deceleration tends to increase due to a disturbance, it is possible to suppress the oscillation of the steering mechanism in a more effective manner in accordance with the vehicle speed. 
     10. A control device ( 50 ) of the above embodiments is a control device to be applied to a straddle type vehicle, the straddle type vehicle including a steering mechanism ( 10 ) that steers a front wheel and a steering damper device ( 20 ) capable of variably generating a damping force working on a rotating action of the steering mechanism, the control device being configured to control the damping force of the steering damper device, wherein 
     the control device controls the damping force, based on a change amount per unit time of steering torque generated in the steering mechanism and a deceleration of the front wheel (S 1 , S 2 , S 3 ). 
     According to this embodiment, the damping force is controlled, based on a change amount per unit time of the steering torque generated in the steering mechanism and the deceleration of the front wheel. Therefore, it is possible to suppress the oscillation of the steering mechanism at the time of braking while turning in accordance with the vehicle state at the time of braking while turning. 
     The invention is not limited to the foregoing embodiments, and various variations/changes are possible within the spirit of the invention.