Method and apparatus for steering a vehicle

Claim 2

A steering apparatus for a vehicle having a front set of steerable wheels and a rear set of steerable wheels arranged in tandem, each of the steerable wheels steerably secured to the vehicle frame, said apparatus comprising: a front steering assembly connected to the front set of steerable wheels and to a steering wheel of the vehicle, said front steering assembly effecting steering movement of the front set of steerable wheels in response to turning of the vehicle steering wheel; a controllable rear steering assembly connected to the rear set of steerable wheels for effecting steering movement of the rear set of steerable wheels in response to a rear steering control signal; means for selecting one of a plurality of steering modes including (i) front wheel only steering, (ii) crab steering, and (iii) curl steering; first sensing means for sensing the steering angle of the front set of steerable wheels and for providing a signal indicative thereof; second sensing means for sensing the steering angle of the rear set of steerable wheels and for providing a signal indicative thereof; and control means connected to said selecting means, said first sensing means, said second sensing means, and said controllable rear steering assembly for providing said rear steering control signal to effect steering movement of the rear set of steerable wheels in response to the selected steering mode and in response to the signal from said first sensing means, said control means effecting a change from one steering mode to another steering mode in response to a change in the selected steering mode only after the rear steerable wheels are sensed to be within a predetermined angle of a straight-ahead direction.

Claim 3

The apparatus of claim 1 further including vehicle speed sensing means connected to said control means for sensing vehicle speed and providing a signal indicative thereof, and actuatable locking means connected to said control means and operatively connected to the vehicle frame and the rear set of steerable wheels for, when actuated by said control means, locking the rear set of steerable wheels in a straight-ahead direction and when the rear set of steerable wheels are in the straight-ahead direction, said control means actuating said locking means when the vehicle speed is sensed to be greater than a speed threshold value stored in said control means.

Claim 4

The apparatus of claim 2 further including data input means accessible to an operator of the vehicle and connected to said control means for establishing the speed threshold value stored in said control means.

Claim 5

The apparatus of claim 2 in which, after the vehicle speed is sensed to be greater than the speed threshold value, said control means actuates said locking means only if the rear set of steerable wheels is sensed to be within a predetermined angle of a straight-ahead direction.

Claim 6

The apparatus of claim 2 wherein said control means deactuates said locking means after sensed vehicle speed decreases below a second predetermined value less than the predetermined value used by the control means to actuate the locking means.

Claim 7

The apparatus of claim 5 further including lock sensing means for sensing if, upon deactuation of said locking means, said locking means has unlocked said rear set of steerable wheels from the vehicle frame and for providing a signal indicative thereof, and wherein, after said control means deactuates said locking means and said lock sensing means indicates that said locking means has not unlocked said rear set of steerable wheels from the vehicle frame, said control means provides said rear steering assembly with said rear steering control signal for a predetermined time period.

Claim 8

The apparatus of claim 2 further including lock sensing means for sensing if, upon actuation of said locking means, said locking means has locked said rear set of steerable wheels to the vehicle frame and for providing a signal indicative thereof, said control means, after actuating said locking means and sensing said locking means has not steerably locked said rear set of steerable wheels to the vehicle frame, providing said rear steering assembly with said rear steering control signal so as to steer the rear steerable wheels toward a straight-ahead direction.

Claim 9

The apparatus of claim 7 wherein said control means effects a reversal of the steering direction of the rear steerable wheels by said rear steering control signal if said rear set of steerable wheels are sensed to have passed the straight-ahead direction and the locking means is sensed to have not locked said rear set of steerable wheels in a straight-ahead direction.

Claim 10

The apparatus of claim 2 wherein said locking means includes a lock actuator mounted to a pivotal portion of the rear steerable wheels, said lock actuator including a slidable locking pin, said lock actuator sliding said locking pin outward when actuated thereby extending the locking pin and sliding said locking pin inward when unactuated, a latching block secured to a frame of the vehicle and including a locking pin receiving groove for, when said locking pin is extended and the rear steerable wheels are in a straight ahead direction, receiving said locking pin so as to maintain the rear steerable wheels in the straight-ahead direction.

Claim 11

The apparatus of claim 9 wherein said locking means further includes spring bias means which, upon actuation of said lock actuator, applies a bias force to said locking pin toward a direction which extends the locking pin.

Claim 12

The apparatus of claim 9 wherein said lock actuator further includes an electric motor and a rotary-to-linear motion converter arranged such that, when said lock actuator is actuated, said electric motor in combination with said rotary-to-linear motion converter slides said locking pin outward.

Claim 13

The apparatus of claim 9 wherein said locking means further includes a locking pin position sensor for, when said locking pin is received in said locking pin receiving groove of the latching block, providing a first electrical signal, and when said locking pin is not received in said locking pin receiving groove of the latching block, providing a second electrical signal.

Claim 14

The apparatus of claim 1 further including data input means connected to said control means for selecting a steering angle ratio to be maintained between the front and rear sets of steerable wheels for the curl and the crab steering modes.

Claim 15

The apparatus of claim 13 wherein said control means has a predetermined maximum steering angle value for the rear set of steerable wheels stored therein, said control means limiting the steering angle of the rear set of steerable wheels to this predetermined maximum rear steering angle value.

Claim 16

A steering apparatus for a vehicle having a front set of steerable wheels and a rear set of steerable wheels arranged in tandem, each of the steering wheels steerably secured to the vehicle frame, said apparatus comprising: a front steering assembly connected to the front set of steerable wheels and a steering wheel of the vehicle, said front steering assembly effecting steering movement of the front set of steerable wheels in response to turning of the vehicle steering wheel; a controllable rear steering assembly connected to the rear set of steerable wheels for effecting steering movement of the rear set of steerable wheels in response to a rear steering control signal; means for selecting one of a plurality of steering modes including (i) front wheel steering only, (ii) crab steering, and (iii) curl steering; first sensing means for sensing the steering angle of the front set of steerable wheels and for providing a signal indicative thereof; second sensing means for sensing the steering angle of the rear set of steerable wheels and for providing a signal indicative thereof; third sensing means for sensing speed of the vehicle and providing a signal indicative thereof; actuatable locking means connected to the vehicle frame and to the rear set of steerable wheels for, when actuated and when said rear set of steerable wheels are in a straight-ahead direction, locking said rear set of steerable wheels in the straight-ahead direction; data input means accessible to and operable by an operator of the vehicle for establishing a rear wheel steering lock speed value; and control means connected to said first, second, and third sensing means, said steering mode selecting means, said actuatable locking means, said data input means, and said controllable rear steering assembly for controlling the steering of the rear set of steerable wheels in response to the selected steering mode and in response to the signal from said first sensing means, said control means actuating said locking means when the sensed vehicle speed is greater than said rear wheel steering lock speed value.

Claim 17

A steering apparatus for a vehicle having a front set of steerable wheels and a rear set of steerable wheels arranged in tandem, each of the steering wheels steerably secured to the vehicle frame, said apparatus comprising: a front steering assembly connected to the front set of steerable wheels and a steering wheel of the vehicle, said front steering assembly effecting steering movement of the front set of steerable wheels in response to turning of the vehicle steering wheel; a controllable rear steering assembly connected to the rear set of steerable wheels for effecting steering movement of the rear set of steerable wheels in response to a rear steering control signal; means for selecting one of a plurality of steering modes including (i) front wheel steering only, (ii) crab steering, and (iii) curl steering; first sensing means for sensing the steering angle of the front set of steerable wheels and for providing a signal indicative thereof; second sensing means for sensing the steering angle of the rear set of steerable wheels and for providing a signal indicative thereof; third sensing means for sensing speed of the vehicle and providing a signal indicative thereof; actuatable locking means connected to the vehicle frame and to the rear set of steerable wheels for, when actuated and when said rear set of steerable wheels are in a straight-ahead direction, locking said rear set of steerable wheels in the straight-ahead direction; data input means accessible to and operable by an operator of the vehicle for establishing a rear wheel steering lock speed value; and control means connected to said first, second, and third sensing means, said steering mode selecting means, said actuatable locking means, said data input means, and said controllable rear steering assembly for controlling the steering of the rear set of steerable wheels in response to the selected steering mode and in response to the signal from said first sensing means, said control means actuating said locking means when the sensed vehicle speed is greater than said rear wheel steering lock speed value.

Claim 18

The apparatus of claim 15 wherein said control means provide said rear steering control signal so as to initially cause said rear steerable wheels to be moved to a straight-ahead direction independent of the selected steering mode and independent of the sensed vehicle speed.

Claim 19

The apparatus of claim 15 in which, after the vehicle speed is sensed to be greater than the rear wheel steering lock speed value, said control means actuates said locking means only if the rear set of steerable wheels is sensed to be within a predetermined angle of a straight-­ahead direction.

Claim 20

The apparatus of claim 15 wherein said control means deactuates said locking means after sensed vehicle speed decreases below a second predetermined value less than the predetermined value used by the control means to actuate the locking means.

Claim 21

The apparatus of claim 18 further including lock sensing means connected to said control means for sensing if said locking means has unlocked said rear set of steerable wheels from the vehicle frame and for providing a signal indicative thereof, and wherein, after said control means has deactuated said locking means, said lock sensing means indicates that said locking means has not unlocked said rear set of steerable wheels from the vehicle frame, said control means providing said rear steering assembly with said rear steering control signal for a predetermined time period.

Claim 22

The apparatus of claim 16 further including lock sensing means connected to said control means for sensing if said locking means has locked said rear set of steerable wheels to the vehicle frame and for providing a signal indicative thereof, said control means, after actuating said locking means and sensing said locking means has not steerably locked said rear set of steerable wheels to the vehicle frame, providing said rear steering assembly with said rear steering control signal so as to steer the rear steerable wheels toward a straight-ahead direction.

Claim 23

The apparatus of claim 20 wherein said control means effects a reversal of the steering direction of the rear steerable wheels if said rear set of steerable wheels are sensed to have passed the straight-ahead direction and the locking means is sensed to have not locked the rear set of steerable wheels to the vehicle frame.

Claim 24

The apparatus of claim 17 wherein said data input means is further used for selecting a steering angle ratio to be maintained between the front and rear steerable wheels for each the curl and crab steering modes.

Claim 25

The apparatus of claim 15 wherein said control means has a predetermined maximum steering angle value for the rear set of steerable wheels stored therein, said control means limiting the steering angle of the rear set of steerable wheels to this predetermined maximum rear steering angle value.

Claim 26

The apparatus of claim 15 wherein said actuatable locking means includes a lock actuator mounted to a pivotal portion of the rear steerable wheels, said lock actuator including a slidable locking pin, said lock actuator sliding said locking pin outward when actuated thereby extending the locking pin and sliding said locking pin inward when unactuated, a latching block secured to a frame of the vehicle and including a locking pin receiving groove for, when said locking pin is extended and the rear steerable wheels are in a straight ahead direction, receiving said locking pin so as to maintain the rear steerable wheels in the straight-ahead direction.

Claim 27

The apparatus of claim 24 wherein said locking means further includes spring bias means which, upon actuation of said lock actuator, applies a bias force to said locking pin toward a direction which extends the locking pin.

Claim 28

The apparatus of claim 24 wherein said lock actuator further includes an electric motor and a rotary-to-­linear motion converter arranged such that, when said lock actuator is actuated, said electric motor in combination with said rotary-to-linear motion converter slides said locking pin outward.

Claim 29

The apparatus of claim 24 wherein said locking means further includes a locking pin position sensor for, when said locking pin is received in said locking pin receiving groove of the latching block, providing a first electrical signal, and when said locking pin is not received in said locking pin receiving groove of the latching block, providing a second electrical signal.

Claim 32

The apparatus of claim 28 further including lock sensing means for sensing if said locking means has locked the rear set of steerable wheels in the straight-ahead direction and for providing a signal indicative thereof, and drive means controlled by said control means for steerably moving the rear set of steerable wheels toward the straight-­ahead direction when said control means actuates said locking means and said signal from said lock sensing means indicates said locking means has not locked the rear set of steerable wheels to the vehicle frame.

Claim 33

The apparatus of claim 29 wherein said control means reverses said drive means if the rear set of steerable wheels are sensed to have been driven past the straight-­ahead direction and said signal from said lock sensing means indicates said locking means has not locked the rear set of steerable wheels in the straight-ahead direction.

Claim 34

The apparatus of claim 28 wherein said locking means includes a lock actuator mounted to a pivotal portion of the rear steerable wheels, said lock actuator including a slidable locking pin, said lock actuator sliding said locking pin outward when actuated thereby extending the locking pin and sliding said locking pin inward when unactuated, a latching block secured to a frame of the vehicle and including a locking pin receiving groove for, when said locking pin is extended and the rear steerable wheels are in a straight ahead direction, receiving said locking pin so as to maintain the rear steerable wheels in the straight-ahead direction.

Claim 35

The apparatus of claim 31 wherein said locking means further includes spring bias means which, upon actuation of said lock actuator, applies a bias force to said locking pin toward a direction which extends the locking pin.

Claim 36

The apparatus of claim 31 wherein said lock actuator further includes an electric motor and a rotary-to-linear motion converter and, when said lock actuator is actuated, sliding said locking pin outward.

Claim 37

The apparatus of claim 31 wherein said locking means further includes a locking pin position sensor for, when said locking pin is received in said locking pin receiving groove of the latching block, providing a first electrical signal, or when said locking pin is not received in said locking pin receiving groove of the latching block, providing a second electrical signal.

Claim 42

The apparatus of claim 36 wherein said actuatable locking means includes an electric motor, a rotary-to-linear motion converter operatively connected to an output shaft of the electric motor and having a member extending therefrom that is driven in linear motion upon rotation of the motor output shaft, a locking pin housing mounted to one of the pivotal portion of the steerable wheel of the vehicle or a frame of the vehicle, said electric motor and said rotary-to-linear motion converter mounted to said locking pin housing, said locking pin housing having a pin receiving bore for slidably holding said locking pin, said extending member of said rotary-to-linear motion converter operatively connected to said locking pin so that linear motion of said extending member slides said locking pin.

Claim 43

The apparatus of claim 36 further including means for sensing the position of said locking pin and for providing one electrical signal when said locking pin is extended and for providing a second electrical signal when said locking pin is not extended.

Claim 46

The method of claim 39 further comprising the steps of sensing vehicle speed and providing a signal indicative thereof, selecting a rear wheel steering lock speed value such that when sensed vehicle speed is greater than the selected rear wheel steering lock speed value it is desirable to maintain the rear steerable wheels in a straight-ahead direction, and providing actuatable locking means operatively connected between the vehicle frame and the rear set of steerable wheels for, when actuated and when the rear set of steerable wheels is in the straight-ahead direction, locking the rear set of steerable wheels in a straight-ahead direction, and actuating said locking means when the vehicle speed is sensed to be greater than the selected rear wheel steering lock speed value.

Claim 47

The method of claim 40 further including the steps of, after the vehicle speed is sensed to be greater than the rear wheel steering lock speed value, said step of actuating said locking means occurs only if the rear set of steerable wheels is sensed to be within a predetermined angle of a straight-ahead direction.

Claim 48

The method of claim 40 further including the step of deactuating said locking means after sensed vehicle speed decreases below a second predetermined value less than the selected rear wheel steering lock speed value.

Claim 49

The method of claim 42 further including the steps of sensing if, upon deactuation of said locking means, said locking means has unlocked the rear set of steerable wheels from the vehicle frame and providing a signal indicative thereof, and if, after deactuating said locking means it is sensed that the locking means has not unlocked the rear set of steerable wheels from the vehicle frame, providing the rear steering assembly with a rear steering control signal for a predetermined time period.

Claim 50

The method of claim 39 further including the steps of sensing if, upon actuation of the locking means, the rear set of steerable wheels is locked to the vehicle frame and providing a signal indicative thereof, and if it is sensed that after actuation of the locking means the rear set of steerable wheels is not locked to the vehicle frame, providing the rear steering assembly with a rear steering control signal so as to steer the rear steerable wheels toward a straight-ahead direction.

Claim 51

The method of claim 44 further including the steps of effecting a reversal of the steering direction of the rear steerable wheels if it is sensed that the rear set of steerable wheels are sensed to have passed the straight-­ahead direction and that the rear set of steerable wheels is not locked to the vehicle frame.

Claim 52

The method of claim 39 further including the steps of selecting a steering angle ratio to be maintained between the front and rear sets of steerable wheels for the curl steering mode and maintaining the selected steering angle ratio when the curl steering mode has been selected.

Claim 53

The method of claim 39 further including the steps of selecting a steering angle ratio to be maintained between the front and rear sets of steerable wheels for the crab steering mode and maintaining the selected steering angle ratio when the crab steering mode has been selected.

Claim 54

The method of claim 46 further including the step of limiting the steering angle of the rear set of steerable wheels to a predetermined maximum rear steering angle value.

Claim 55

The method of claim 48 further including the step of limiting the steering angle of the rear set of steerable wheels to a predetermined maximum rear steering angle value.

Claim 58

The method of claim 50 further including the steps of initially causing said rear steerable wheels to be steered to a straight-ahead direction independent of the selected steering mode and independent of the sensed vehicle speed.

Claim 59

The method of claim 50 in which the step of actuating the locking mechanism upon the vehicle speed being sensed to be greater than the rear wheel steering speed only occurs if the rear set of steerable wheels is sensed to be within a predetermined angle of a straight-ahead direction.

Claim 60

The method of claim 50 further including the step of deactuating the locking means after sensed vehicle speed decreases below a second predetermined value less than the value used to actuate the locking means.

Claim 61

The apparatus of claim 53 further including the steps of sensing if, upon the step of deactuating the locking means, the locking means has unlocked the rear set of steerable wheels from the vehicle frame and providing a signal indicative thereof, and after the locking means is deactuated but the locking means is sensed to not be unlocked, providing the rear steering assembly with the rear steering control signal for a predetermined time period.

Claim 62

The method of claim 51 further including the steps of sensing if, upon the step of actuating the locking means, the locking means has locked the rear set of steerable wheels to the vehicle frame and providing a signal indicative thereof, and after actuating the locking means and sensing the locking means has not steerably locked the rear set of steerable wheels to the vehicle frame, providing the rear steering assembly with the rear steering control signal so as to steer the rear steerable wheels toward a straight-ahead direction.

Claim 63

The method of claim 55 further including the steps of effecting a reversal of the steering direction of the rear steerable wheels if, after being steered to the straight-ahead direction, the locking means is sensed to have not locked and the rear set of steerable wheels are sensed to have passed the straight-ahead direction.

Claim 64

The apparatus of claim 52 further including the steps of selecting a steering angle ratio to be maintained between the front and rear steerable wheels for the curl steering mode and maintaining the selected steering angle ratio when the curl steering mode is selected.

Claim 65

The apparatus of claim 52 further including the steps of selecting a steering angle ratio to be maintained between the front and rear steerable wheels for the crab steering mode and maintaining the selected steering angle ratio when the crab steering mode is selected.

Claim 66

The apparatus of claim 50 further including the step of limiting the steering angle of the rear set of steerable wheels to a predetermined maximum rear steering angle value.