Patent Publication Number: US-2011065067-A1

Title: Steering for drive simulator and drive simulator

Description:
TECHNICAL FIRLED 
     The present invention relates to a drive simulator simulating a driving behavior of a vehicle, ship or the like and a steering therefor. 
     BACKGROUND ART 
     There is known a drive simulator for a driver to operate a steering wheel, while watching an image displayed on a display unit. For example, a drive simulator for a game of displaying a view from a front window of a car on the display unit and a player watching the display unit while operating the steering wheel, gas pedal, a brake and a shift lever is offered commercially or installed on a game center as a game machine for business use. 
       FIG. 9  is a schematic view of a conventional steering for drive simulator. A steering wheel  1  is connected to a spur gear  2  of large diameter. The spur gear  2  of large diameter engages a spur gear  3  of small diameter. The spur gear  3  of small diameter is connected to a motor  4  which applies a load on the steering wheel  1 . A rotational angle of the motor  4  is detected by an encoder  5 . 
     When the spur gear  2  of large diameter engages the spur gear  3  of small diameter, the rotational speed of the motor  4  is reduced, which is transferred to the steering wheel  1 . The motor  4  gives a torque of opposite direction to the steering wheel  1  when the player rotates the steering wheel  1 , or gives rattling load to the steering wheel  1  when the car is moved onto a curbstone during the simulation. This is for giving the feeling of actually driving a car to the player 
     Here, though it is not the steering for drive simulator, the patent document 1 discloses use of a worm gear in the brake for drive simulator. 
     [Patent document 1] Japanese Patent Application Laid-open No. 2005-257029 (see claims) 
     DISCLOSURE OF THE INVENTION 
     Problems to be Solved by the Invention 
     However, in a conventional steering for drive simulator using gears in the deceleration mechanism, there is a problem that backlash occurs due to use of the gears. When the steering wheel is rotated, first there is a play corresponding to the backlash and then, the gears get abutting to each other. Each time the steering wheel is rotated, the play of backlash and rattling gear noise occur, which makes it difficult for the player to feel like driving a car actually. The play of backlash is different from a play of an actual car steering wheel and there is almost no play in the steering wheel of a racing car. 
     In addition, when there is a play of backlash, even if fine vibration is input from the motor, the vibration is absorbed into the play of backlash and is not transmitted to the steering wheel. Further, when the gears are used in the deceleration mechanism, the deceleration mechanism is arranged in the direction perpendicular to the center line of the steering wheel and therefore, the steering is shaped different from the steering of an actual car. 
     That is, in the steering for drive simulator using gears in the deceleration mechanism, there are problems that the player cannot feel like driving a car actually and is disappointed. 
     Then, the present invention has an object to provide a steering for drive simulator and a dive simulator capable of offering a player the feeling of driving an actual car. 
     Means for Solving the Problems 
     The present invention will be described below, in which the reference numerals in the accompanying drawings are added within parentheses for easy understanding of the present invention, however, this is not intended for limiting the present invention to what is shown in the drawings. 
     In order to solve the above-mentioned problems, the invention of claim  1  is a steering for drive simulator comprising: a first screw shaft ( 12 ,  54 ) which is connectable to a steering wheel ( 61 ) and rotatable around an axial line together with the steering wheel ( 61 ); a first nut ( 13 ,  56 ) which is fit on the first screw shaft ( 12 ,  54 ) and moves linearly in an axial direction of the first screw shaft ( 12 ,  54 ) with rotation of the first screw shaft ( 12 ,  54 ); a second screw shaft ( 15 ,  55 ) which is connectable to a motor ( 68 ), in parallel with the first screw shaft ( 12 ,  54 ) and rotatable around the axial line; and a second nut ( 16 ,  57 ) which is fit on the second screw shaft ( 15 ,  55 ), moves linearly in an axial direction of the second screw shaft ( 15 ,  55 ) with rotation of the second screw shaft ( 15 ,  55 ) and is connected to the first nut ( 13 ,  56 ). 
     The invention of claim  2  is characterized in that in the steering for drive simulator of claim  1 , a lead of the first screw shaft ( 12 ,  54 ) is greater than a lead of the second screw shaft ( 15 ,  55 ). 
     The invention of claim  3  is characterized in that in the steering for drive simulator of claim  1 , a detector for detection a rotation angle of the first screw shaft ( 12 ,  54 ) is mountable on the first screw shaft ( 12 ,  54 ). 
     The invention of claim  4  is characterized in that in the steering for drive simulator of claim  1  or  2 , the first nut ( 13 ,  56 ) is a first ball screw nut with a plurality of rolling elements ( 22 ) arranged rotatably between the first ball screw nut and the first screw shaft ( 12 ,  54 ), and the second nut ( 16 ,  57 ) is a second ball screw nut with a plurality of rolling elements arranged rotatably between the second ball screw nut and the second screw shaft ( 15 ,  55 ). 
     The invention of claim  5  is characterized by in the steering for drive simulator of anyone of claims  1  to  4 , further comprising a stopper ( 50 ) made of viscoelasticity material for limiting moving amounts of the first nut ( 13 ,  56 ) and the second nut ( 16 ,  57 ) in the axial direction. 
     The invention of claim  6  is characterized by in the steering for drive simulator of anyone of claims  1  to  5 , further comprising a linear motion guide ( 39 ) for guiding at least one of the first nut ( 13 ,  56 ) and the second nut ( 16 ,  57 ). 
     The invention of claim  7  is a drive simulator comprising: a steering for drive simulator having a steering wheel ( 61 ); an angle detector ( 67 ) for detecting a rotation angle of the steering wheel ( 61 ); a motor ( 68 ) for giving a load to the steering wheel ( 61 ); a display unit ( 66 ) for displaying an image; a simulation controller ( 70 ) for changing the image displayed on the display unit ( 66 ) based on a signal from an operation input part ( 73 ) including the steering wheel ( 61 ); a motor controller ( 69 ) for controlling the motor ( 68 ) based on the rotation angle detected by the angle detector ( 67 ); and the steering for drive simulator having a first screw shaft ( 12 ,  54 ) which is connectable to the steering wheel ( 61 ) and rotatable around an axial line together with the steering wheel ( 61 ); a first nut ( 13 ,  56 ) which is fit on the first screw shaft ( 12 ,  54 ) and moves linearly in an axial direction of the first screw shaft ( 12 ,  54 ) with rotation of the first screw shaft ( 12 ,  54 ); a second screw shaft ( 15 ,  55 ) which is connectable to the motor ( 68 ), in parallel with the first screw shaft ( 12 ,  54 ) and rotatable around the axial line; and a second nut ( 16 ,  57 ) which is fit on the second screw shaft ( 15 ,  55 ), moves linearly in an axial direction of the second screw shaft ( 15 ,  55 ) with rotation of the second screw shaft ( 15 ,  55 ) and is connected to the first nut ( 13 ,  56 ). 
     EFFECTS OF THE INVENTION 
     According to the invention of claim  1 , as the two-stage screw mechanisms are combined into the deceleration mechanism of the steering for drive simulator, the play of the deceleration mechanism can be reduced. In addition, as the shape is such as extending straightly from the steering wheel, it is close to the steering of an actual car. 
     According to the invention of claim  2 , as rotation of the motor is decelerated to be transferred to the steering wheel, conversely, it becomes possible to accelerate the rotation of the steering wheel and transfer it to the motor. 
     According to the invention of claim  3 , it is possible to detect the rotational angle of the steering wheel directly. On the other hand, when the rotational angle of the second screw shaft is detected, it needs to be converted into the rotational angle of the first screw shaft. 
     According to the invention of claim  4 , as the first and second nuts are ball screw nuts, it is possible to reduce the backlash to zero. 
     According to the invention of claim  5 , when the first nut and the second nut abut to the stopper of viscoelasticity material to limit the rotation of the steering wheel, it is possible to give the player a feeling close to the feeling of driving a car actually. 
     According to the invention of claim  6 , if moment is applied to the first nut and the second nut, they can be moved in the axial direction. 
     According to the invention of claim  7 , as the two-stage screw mechanisms are combined into the deceleration mechanism of the steering for drive simulator, the play of the deceleration mechanism can be reduced. In addition, as the shape is such as extending straightly from the steering wheel, it is close to the steering of an actual car. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a steering according to one embodiment of the present invention. 
         FIG. 2  is a plan view of the steering. 
         FIG. 3  is a side view of the steering. 
         FIG. 4  is a perspective view of a first ball screw mechanism. 
         FIG. 5  is a perspective view illustrating an actuator having integrally formed linear motion guide and second ball screw mechanism. 
         FIG. 6  is a cross sectional view of another example of the steering. 
         FIG. 7  is an outline view of a drive simulator. 
         FIG. 8  is an overall structural view of the drive simulator. 
         FIG. 9  is a schematic view of a conventional steering. 
     
    
    
     REFERENCE NUMERALS 
     
         
           12 ,  54  . . . first screw shaft 
           13 ,  56  . . . first ball screw nut (first nut) 
           15 ,  55  . . . second screw shaft 
           16 ,  57  . . . second ball screw nut (second nut) 
           22  . . . ball (rolling element) 
           34  . . . rail 
           37  . . . ball train 
           39  . . . liner motion guide 
           50  . . . stopper 
           51  . . . rail 
           53  . . . rolling element 
           61  . . . steering wheel (operation input section) 
           62  . . . gas pedal (operation input section) 
           63  . . . brake (operation input section) 
           64  . . . shift lever (operation input section) 
           66  . . . display unit 
           67  . . . angle detector 
           68  . . . motor 
           69  . . . motor driver (motor controller) 
           70  . . . simulation controller 
           72  . . . display unit 
           73  . . . operation input section 
       
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     With reference to the attached drawings, a steering for drive simulator (hereinafter also referred simply to “steering”) according to an embodiment of the present invention will be described below.  FIGS. 1 to 3  are overall views of the steering.  FIG. 1  is a perspective view,  FIG. 2  is a plan view and  FIG. 3  is a side view of the steering. The steering has combination of a first ball screw mechanism  14  and a second ball screw mechanism  17  vertically aligned at two stages. A screw shaft  12  of the upper-stage first ball screw mechanism and a screw shaft  15  of the lower-state ball screw mechanism  17  are in parallel with each other. 
     The lead of the first screw shaft  12  is greater than that of the second screw shaft  15 . For example, a ratio of the lead of the first screw shaft  15  to the lead of the second screw shaft  15  is set to be 30 to 50:1. Rotation of the second screw shaft  15  is decelerated to, for example, 1/(30 to 50) and transmitted to the first screw shaft  12 . On the other hand, rotation of the first screw shaft  12  is accelerated by 30 to 50 times to be transmitted to the second screw shaft  15 . 
     The steering has an elongating and rectangular base plate  18 . At both ends of the base plate  18  in the longitudinal direction, a pair of brackets  19   a ,  19   b  is attached to support the first screw shaft  12  rotatable. The first screw shaft  12  is supported by the brackets  19   a ,  19   b  via bearings  20  and  21  so as to rotate around the axial line. 
     In an outer circumferential surface of the first screw shaft, a spiral ball rolling groove  12   a  is worked with a predetermined lead (see  FIG. 4 ). As balls  22  roll thereon as rolling elements, the surface of the ball rolling groove  12   a  is finished to be smooth and have high strength (rigidity). 
     As illustrated in  FIG. 1 , the first screw shaft  12  is connected at an end thereof to a wheel connection shaft  25 . The center line of the first screw shaft  12  and the center line of the wheel connection shaft  25  are in agreement with each other. At the tip end of the wheel connection shaft  25 , a wheel holding section  26  is provided in shape of circular cylinder. The wheel holding section has a plurality of mounting holes  26   a  in the circumferential direction. When mounting screws are made to pass through the mounting holes  26   a  to fit in the steering wheel attached to the wheel holding section  26 , the steering wheel is fixed to the wheel holding section  26 . 
     At the other end of the first screw shaft  12 , a detection shaft  27  jutting from the bracket  19   b  is connected thereto. An angle detector (not shown) such as an encoder is attached to the detection shaft  27 . As the detection shaft  27  is connected to the first screw shaft  12 , the angle detector is able to detect a rotation angle f the steering wheel directly. 
       FIG. 4  is a detailed view of a firs nut (first ball screw nut) fit in the first screw shaft  12 . The first ball screw nut  13  has a nut main body  31  having a loaded ball rolling groove  31   a  formed in the inner surface thereof and a pair of endcaps provided at respective ends of the nut main body  31 . As the balls  22  roll thereon, the surface of the loaded ball rolling groove  31   a  is finished to be smooth and have high strength. The nut main body  31  has a ball return passage  31   b  passing through the nut main body in the axial direction for circulation of the balls  22 . In each of the endcaps  32 , a direction change passage  32   a  is formed scooping each ball  22  rolling in the ball rolling groove  12   a  of the first screw shaft  12  to lead the ball to the ball return passage  31   b.    
     A loaded ball rolling passage between the ball rolling groove  12   a  of the first screw shaft  12  and the loaded ball rolling groove  31   a  of the nut main body  31 , the direction change passages  32   a  and ball return passage  31   a  consist in a ball circulation passage in which the plural balls  22  are arranged. 
     When the first screw shaft  12  is rotated, the first ball screw nut  13  fit on the first screw shaft  12  via the balls  22  moves in the axial direction. At the same time, the balls  22  circulate in the ball circulation passage. Once each of the balls  22  roll up to an end of the loaded ball rolling passage, it is scooped up into the direction change passage  32   a  of the endcap  32 , moves in the ball return passage  31   b  and then is returned from the opposite-side endcap  32  back into the other end of the loaded ball rolling passage. 
     Here, the ball circulation passage may be, instead of the above-described endcap type ball circulation passage, a return pipe type circulation passage or a deflector type circulation passage. 
     As illustrated in  FIG. 1 , the flange  13   a  of the first ball screw nut  13  is connected to an L-shaped bracket  33 . To the bottom surface of the L-shaped bracket  33 , the second ball screw nut  16  as a second nut is connected. 
       FIG. 5  illustrates an actuator having the second ball screw device  17 , a linear motion guide  39  integrally provided therein. A block  36  is arranged inside of side walls  34   a  of a rail  34  of U-shaped cross section. The block  36  sandwiched between the side walls  34   a  in pair of the rail  34  moves linearly in the longitudinal direction of the rail  34  along the rail  34 . In both side surfaces of the block  36 , a plurality of ball trains  37  is arranged. At the inside of the side wall  34   a  of the rail  34 , ball rolling grooves  34   b  are formed extending in the longitudinal direction of the rail  34 . The ball rolling grooves  34   b  guide rolling of ball trains  37  in both side surfaces. The rail  34  and the ball trains  37  in both side surfaces of the block  36  consist in the linear motion guide  39  for guiding linear motion of the block  36 . 
     Here, the linear guide part  39  may be a linear guide having a raceway rail and a saddle-shaped moving block arranged thereon or a ball spline having a spline shaft and an outer cover moving along the spline shaft as far as it can guide linear movement of the second ball screw nut  16 . 
     The second screw shaft  15  of the second ball screw mechanism  17  passes through the block  36 . In the outer surface of the second screw shaft  15 , ball rolling grooves  15   a  are formed with a predetermined lead. The lead of the second screw shaft  15  is smaller than that of the fist screw shaft  12 . As the balsas rolling elements roll thereon, the surfaces of the ball rolling grooves  15   a  are finished to be smooth and have high strength (rigidity). 
     Both ends of the second screw shaft  15  are supported by end housings  43  and  44  provided at both ends of the rail  34  in the longitudinal direction via the bearings  41  and  42 . The second screw shaft  15  is able to rotate round the axial line. At an end of the second screw shaft  15 , a joint  45  is attached thereto. At an end of the rail  34  in the longitudinal direction, a motor support housing  46  is provided on which a motor is mounted. The motor is connected to the second screw shaft  15  by mounting the motor on the motor support housing  46  and connecting an output shaft of the motor to the joint  45 . 
     In the block  36 , the second ball screw nut  16  is embedded. The ball screw nut  16  is fit on the second screw shaft  15  passing in the block  36 . In the inner surface of the second ball screw nut  16 , like the first ball screw nut  13 , a spiral loaded ball rolling groove is formed facing the ball rolling groove  15   a  of the second screw shaft  15 . Besides, the second ball screw nut  16  has a ball circulation passage including the loaded ball rolling groove. The type of the ball circulation passage may be, like the first ball screw nut  13 , the return pipe type, the endcap type, the deflector type or any other type. In the ball circulation passage, a plurality of balls is arranged. When the second screw shaft  15  is rotated, the second ball screw nut  16  moves in the axial direction and the plural ball circulates in the ball circulation passage. 
     The next description is made about the operation of a deceleration mechanism when the lead of the first ball screw mechanism  14  is, for example, 30 to 50 mm and the lead of the second ball screw mechanism  17  is, for example 1 mm (see  FIG. 1 ). In this case, when the steering wheel is rotated one turn, the first ball screw nut  13  moves 30 to 50 mm linearly. As the first ball screw nut  13  and the second ball screw nut  16  are connected to each other, the second ball screw nut  16  also moves 30 to 50 mm linearly together with the first ball screw nut  13 . When the second ball screw nut  16  moves linearly, the linear motion of the second ball screw nut  16  is converted into rotation and the second screw shaft  15  rotates. As the lead of the second ball screw mechanism  17  is 1 mm, when the second ball screw nut  16  moves 30 to 50 mm linearly, the second screw shaft  15  rotates 30 to 50 turns. On the other hand, when the motor is used to rotate the second screw shaft  15 , when the second screw shaft  15  rotates 30 to 50 turns, the first screw shaft  12  rotates one turn. 
     The motor is provided to give the steering wheel a load. For example, when the player rotates the steering wheel, the motor gives a torque in the opposite direction to the direction where the player rotates the wheel. This is for giving the player an operation feeling line operating an actual car. The torque with which the player rotates the steering wheel is significantly large. If the motor is connected to the first screw shaft, a huge motor would be required to create a torque corresponding to the torque of the player. As the output shaft of the motor is decelerated to be transmitted to the first screw shaft  12 , the motor can be downsized (the motor torque can be reduced to 1/30 to 50 in the present embodiment), and a motor of appropriate size can be selected to be embedded in the steering. 
     In addition, as the balls  22  are interposed between the first ball screw nut  13  and the first screw shaft  12  and preloaded, the space in the first ball screw mechanism  14  can be reduced to zero. Likewise, as the balls are interposed between the second ball screw nut  16  and the second screw shaft  15  and preloaded, the space in the second ball screw mechanism  17  can be reduced to zero. As these first ball screw mechanism  14  and second ball screw mechanism  17  are combined into the deceleration mechanism and the space in this deceleration mechanism can be reduced to zero, the deceleration mechanism can be provided with no play. 
     As illustrated in  FIG. 1 , on the base plate  18 , stoppers  50  are provided via respective stopper support plates  48 . The stoppers  50  are made of viscoelasticity material such as urethan or rubber. The plural stoppers  50  are provided facing each other with a predetermined space given in the longitudinal direction of the base plate  18 . When the lower part of the L-shaped bracket  33  fixed to the first ball screw nut  13  abuts to the stopper  50 , movement in the axial direction of the first ball screw nut  13  and the second ball screw nut  16  is restricted. The stoppers  50  also limit the rotation angle in the clockwise and counterclockwise directions of the steering wheel. 
       FIG. 6  is a cross sectional view illustrating another example of the steering. In a tube-shaped rail  51 , a block  52  is held movable in the axial direction. Movement of the block  52  is guided by a linear motion guide, that is, rolling elements  53  and ball rolling grooves  51   a  in the inner circumferential surface of the rail  51 . In the block  52 , a first screw shaft  54  and the second screw shaft  55  pass therethrough. A first ball screw nut  56  is fit on the first screw shaft  54  and a second ball screw nut  57  is fit on the second screw shaft  55 . As the first screw shaft  54  and the second screw shaft  55  are held in tube-shaped rail  51 , the steering can be of compact size. 
       FIG. 7  is an outline view of a drive simulator having the steering of the present invention embedded therein. In the drive simulator, a steering wheel  61 , a gas pedal  62 , a brake  63 , a shift lever  64  and the like are arranged as operation input part operable by a player. The player sits on a seat  65  and operates the operation input part such as the steering wheel  61  while watching a display unit  66  arranged in front thereof. On the display device  66 , for example, a racing car driving in a town course or a circuit course is displayed. Then, the player drives the racing car and competes against computer cars driven by a simulator controller as to ranking or driving time. 
       FIG. 8  is an overall structural view of the drive simulator. The drive simulator has the steering wheel  61 , an angle detector  67  such as an encoder connected to the first screw shaft  12  of the steering, a motor  68  which is connected to the second screw shaft  15  of the steering and gives a load to the steering wheel  61 , a motor driver  69  as motor controller for controlling the motor  68 , a simulation controller  70  for executing drive simulation, a display controller  71  for creating various image data and a display unit  72  for displaying the image data. 
     The motor driver  69  controls the motor  68  for giving a load to the steering wheel  61 . The motor driver  69  receives a rotation angle signal of the steering wheel  61  detected by the angle detector  67 . The motor driver  69  calculates a rotation angle and a rotation speed of the steering wheel  61 . 
     The simulation controller  70  calculates a parameter in accordance with progress of a game or speed of the racing car driven by the player and outputs it to the motor driver  69 . The motor driver  69  uses the parameter output from the simulation controller  70  and the rotation angle and rotation speed of the steering wheel  61  as a basis to control a current (torque) passing through the motor  68 . With this structure, the steering wheel  61  can be given a reaction force close to that of an actual racing car. For example, when the rotation angle of the steering wheel  61  is larger and the car speed is higher, the motor driver  69  controls to increase the torque of the motor  68 . On the other hand, when the racing car runs over the curbstone, for example, the motor driver  69  increases and reduces the torque to the motor  68  so that a rattling load to the steering wheel  61 . 
     The simulation controller  70  performs various calculations relating to drive games in accordance with operations of the operation input part  73  including the steering wheel, a gas pedal, a brake, a shift lever and the like. The calculation results are sent to the display controller  71 . The display controller  71  creates various image data and displays it on a display unit  72 . For example, the display unit  72  displays a front scenery that can be viewed by a player via a front window of a racing car. 
     Here, the simulation controller may make such a control that the seat  65  is inclined so as to give a player a sense of acceleration while the game is in process and the seat  65  is swayed for example when the racing car runs on a curbstone. 
     The present invention is not limited to the above-described embodiments but may be embodied in various forms without departing from the scope of the present invention. For example, the first ball screw mechanism and the second screw mechanism may be sliding type screw mechanisms with no rolling element arranged therein. 
     Further, the steering for drive simulator of the present invention is applicable not only to game machines but also drive simulators in driving schools and the like. Also, it is applicable not only to cars but also other vehicles such as ships.