WO2002081275A1

WO2002081275A1 - Multi-wheel drive vehicle having extendable and retractable wheel assembly

Info

Publication number: WO2002081275A1
Application number: PCT/US2002/009965
Authority: WO
Inventors: Guenter Meier; Thomas Strothmann
Original assignee: Invacare Corporation
Priority date: 2001-04-09
Filing date: 2002-03-28
Publication date: 2002-10-17

Abstract

A multi-wheel drive vehicle is provided that can be operated in, for example, two or four-wheel drive configuration. In this regard, a four-wheel drive vehicle is disclosed as having an extendable and retractable supplementary wheel assembly utilized for removing one or more forward wheel drives from engagement with a driving surface. In this manner, the four-wheel drive vehicle is configured in a two-wheel drive mode with the rear wheel drives responsible for driving and steering the vehicle. So configured, the vehicle can maneuver through turns more precisely than in the four-wheel drive configuration.

Description

MULTI-WHEEL DRIVE VEHICLE HAVING RETRACTABLE WHEEL

FIELD OF THE INVENTION

[0001] The invention relates generally to multi-wheel drive vehicles and, more particularly, to multi-wheel drive vehicles having at least one extendable and retractable wheel.

BACKGROUND OF THE INVENTION

[0002] Generally, a multi-wheel drive vehicle is any vehicle that has more than one wheel that is used to power or drive the vehicle. Examples of such vehicles include two and four wheel drive wheelchairs. Driving such vehicles in straight lines does not pose significant maneuverability issues. However, this is generally not the case when trying to make a tight turn with a four-wheel drive vehicle. This is because normally the two front wheels of a four-wheel drive vehicle influence the minimum turning radius of the vehicle. This fact, coupled with the typical locations of each wheel drive, generally determines the minimum radius the vehicle can make during a turn. As is often the case, this minimum radius is not sufficient to make turns of small radii such as, for example, when traveling down a narrow hallway and attempting to make a turn into an adjacent doorway opening of customary dimensions. The driver of such a vehicle must often make several partial turns by incrementally moving the vehicle forward and backward until the vehicle can properly enter the doorway opening .

[0003] This is a highly disadvantageous scenario for several reasons. First, it detracts from the advantageous mobility characteristics that four-wheel drive vehicles generally offer. Second, by having to position and reposition the vehicle before making the aforementioned turn, energy is expended from the vehicle's energy source thereby reducing the overall range the vehicle can travel between refueling or recharging. Third, it causes excessive wear and tear on the vehicle's wheels and the driving surface. Hence, a system and method that does not suffer from the aforementioned drawbacks is highly desirable.

SUMMARY OF THE INVENTION

[0004] According to one embodiment of the present invention, a multi-wheel drive vehicle is provided. The vehicle includes, for example, a frame, at least two rear wheel drives attached to the frame, at least two wheel drives forward of the rear wheel drives and attached to the frame, and at least one extendable and retractable wheel coupled to the frame forward of the rear wheel drives . The vehicle further includes logic for extending and retracting the at least one extendable and retractable wheel and logic for adjusting the drive configuration of the vehicle based on the state (i.e., extended or retracted) of the at least one extendable and retractable wheel .

[0005] In this regard, the at least one extendable and retractable wheel is employed to remove or disengage all of the wheel drives forward of the rear wheel drives from the driving surface. This is preferably accomplished by the extendable and retractable wheel contacting the driving surface when in the extended state and lifting the forward portion of the frame until the forward wheel drives are no longer in contact with the driving surface. The logic disengages the forward wheel drives and utilizes the rear wheel drives for driving and steering the vehicle. So configured, the forward wheel drives no longer limit the turning radius of the vehicle.

[0006] Therefore, it is an advantage of the present invention to provide a four or more wheel drive vehicle that is capable of making turns of smaller radii than, for example, conventional four-wheel drive vehicles .

[0007] It is another advantage of the present invention to provide a vehicle that can be utilized in a two or four-wheel drive mode . [0008] It is yet another advantage of the present invention to provide a four or more wheel drive vehicle having an extendable and retractable supplementary wheel assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] In the accompanying drawings which are incorporated in and constitute a part of the specification, embodiments of the invention are illustrated, which, together with a general description of the invention given above, and the detailed description given below, serve to example the principles of this invention.

[0010] Figure 1 is a general block diagram of a system 100 of the present invention.

[0011] Figure 2 is a partial perspective view of certain components of the present invention including the frame and supplementary wheel assembly.

[0012] Figures 3 and 4 are front and side elevational views, respectively, of the present invention in four-wheel drive mode.

[0013] Figures 5 and 6 are front and side elevational views, respectively, of the present invention in two-wheel drive mode.

[0014] Figure 7 is a flowchart generally illustrating the logic executed by the present invention in effecting the two and four-wheel drive configurations.

DETAILED DESCRIPTION OF ILLUSTRATED EMBODIMENT

[0015] Illustrated in Figure 1 is a block diagram of a system 100 of the present invention. System 100 has a controller 102, logic 104, drive input device 106, wheel drives 108, 110, 112, and 114, and a supplementary wheel drive assembly 116. Controller 102 is any computer-based controller suitable for controlling a vehicle. In this regard, controller 102 generally has a processor, memory, and input/output components. Controller 102 can also have electric motor drive circuitry associated therewith. [0016] Input device 106 is in circuit communication with controller 102 and provides input signals thereto. More specifically, input device 106 is preferably a user manipulable device such as a joystick or other similar device. In this regard, input device 106 at least provides vehicle velocity and turning vector information. Generally, such vector information is in the form of magnitude and direction information. In its simplest form, input device 106 outputs "x" and ^λy" Cartesian coordinate information wherein the ⁿx" coordinate relates to turning vector information and the ^λλy" coordinate relates to velocity vector information.

[0017] Wheel drives 108, 110, 112, and 114 are also in circuit communication with controller 102. Each wheel drive preferably as a wheel component and a drive component . The drive component is preferably responsible for driving the wheel component and can be in the form of any one of a number of embodiments. For example, one embodiment of a drive component is a gearless, or transmissionless, brushless electric motor. Another embodiment of a drive component is a brushed electric motor and a gearbox, or transmission, communicating with the wheel component. Each wheel drive may also have electric motor drive circuitry associated therewith that receives drive control signals from controller 102 and correspondingly translates these control signals to properly drive the wheel drive. Other embodiments include combustion engines with electronic or hydraulic transmissions. For example, a single combustion engine may be coupled with a transmission system that allows each drive wheel to be driven at a different velocity. Further variations of these embodiments are also intended to fall within the scope of the present invention. Hence, the present invention is applicable to and includes numerous embodiments of wheel drives .

[0018] Additionally, the forward most wheel drives 112 and 114 are preferably connected via a servo steering mechanism that is employed during four or all-wheel drive mode. While the servo steering mechanism ' can take many forms, it is preferably in the form of a rack-and-pinion steering mechanism or other device which translates angular information to the forward wheel drives.

[0019] The supplementary wheel assembly 116 is also in circuit communication with controller 102. As will be discussed in more detail, supplementary wheel assembly 116 has, for example, an actuator assembly 118 and at least one wheel 120. In this regard, actuator -assembly 120 extends and retracts wheel 120 based on control signals from switch 122.

[0020] The logic 104 of the present invention controls the extending and retracting of supplementary wheel assembly 116 and * configures the vehicle in either two or four-wheel drive mode. As will be described in connection with Figure 9, logic 104 reads the output of user manipulable switch 122 to either extend or retract supplemental wheel assembly 116. Based on whether the supplemental wheel assembly 116 is in the extended or retracted state, logic 104 also configures the vehicle in either two or four-wheel drive mode .

[0021] In the preferred embodiment, system 100 is applied to a vehicle such as, for example, a four-wheel drive wheelchair. However, system 100 is applicable to other multi-wheel drive vehicles such as scooters, golf carts, and all-terrain vehicles just to name a few examples. Generally, any vehicle having more then one wheel drive can benefit from the present invention. t0022] Referring now to Figures 2 and 4, the supplementary wheel drive assembly 116 will now be described in more detail. In this regard, Figure 2 is a partial perspective view of supplementary wheel assembly 116 and its relationship to frame 202 and Figure 4 is a side elevational view of vehicle 200 also illustrating the relationship between supplementary wheel assembly 116 and frame 202. Principally, vehicle 200 includes a frame 202 having top and bottom portions 204 and 206 respectively. Frame 202 further includes vertical and horizontal cross-braces 205 and 207, respectively. Coupled to frame 202 is supplemental wheel assembly 116.

[0023] In this regard, supplemental wheel assembly 116 has wheel 118, pivot arm 210, and actuator assembly 120. Actuator assembly 120 preferably includes a motor 214 and an actuating mechanism 216. In the preferred embodiment, motor 214 comprises an electric motor and, optionally, a gearbox. Actuating mechanism 216 preferably comprises an actuator having a component capable of linear displacement. Other embodiments of actuator assembly 120 include hydraulic linear actuators and servos where a fluid such, as for example, hydraulic fluid is used to accomplish the linear extension and retraction of the actuating mechanism 216.

[0024] Actuating assembly 120 is pivotally coupled at one end to frame 202 via bracket 218 and pin or bolt 220. The other end of actuating assembly 120 is pivotally coupled to pivot arm 210 via pin or bolt 222. Pivot arm 210 has a swivel assembly 208 to which wheel 118 is mounted. Swivel assembly 208 allows wheel 118 to spin on an axis running through the approximate center line of the assembly. Pivot arm 210 is itself pivotally coupled to bottom portion 206 of frame 202 via a pair of brackets and pivot connection 212. Pivot connection 212 preferably has a pin or bolt that is secured and passes though openings in the frame brackets and pivot arm 210 thereby allowing pivotal motion.

[0025] Supplementary wheel assembly bracket 218 is rigidly affixed to horizontal cross-brace 207 and includes a substantially vertical riser portion 224 which terminates to an angled section 226. As shown, bracket 218 is coupled to horizontal cross-brace 207 at a position that is within the extremities of frame 202 and, more preferably, slightly off- center and between vertical cross-braces 205. (See also Figure 3) . Horizontal cross-brace 207 is coupled to vertical cross- braces 205 laterally between top and bottom portions 204 and 206 and slightly offset towards top portion 204. However, it should be noted that these^* positions describe the illustrated embodiment and can be modified therefrom without departing from the teachings of the present invention. So configured, actuating assembly 120 extends and retracts wheel 118 by moving pivot arm 210 through an arcuate motion, as will be described in more detail with reference to Figures 3-6.

[0026] Referring now to Figures 3 and 4, side and front elevational views of vehicle 200 in four-wheel drive mode with certain components cut away to more clearly illustrate the present invention are shown. In this regard, vehicle 200 is shown with supplemental wheel assembly 116 in the retracted position. In four-wheel drive mode, wheel drives 108, 110, 112, and 114 are normally, in contact with the driving surface. As will be described in connection with Figure 7, such a configuration is normally obtained by switching user manipulable switch 122 to the "retract" position.

[0027] The four or all-wheel drive mode provides the vehicle with important drive characteristics. First, the four or all- wheel drive mode is most advantageous on difficult surfaces such as, for example, rough terrain. Second, it also provides for a higher speed on such difficult surfaces because of its four or all-wheel drive characteristic. Third, it provides for lower power consumption on, for example, sideward slopes, because the front wheel drives provide servo steering. Without servo steering, additional energy must be expended by the vehicle to maintain the vehicle's direction of travel. Fourth, it provides the vehicle with better stability.

[0028] Illustrated in Figures 5 and 6 are side and front elevational views of vehicle 200 in two-wheel drive mode with once again certain components cut away to more clearly illustrate the present invention. In this regard, vehicle 200 is shown with supplemental wheel assembly 116 in the extended position. In two-wheel drive mode, supplemental wheel assembly 116 lifts the forward portion of frame 202 so that drive wheels 112 and 114 are no longer contact the driving surface. As will be described in more detail in connection with Figure 7, this configuration is normally obtained by switching user manipulable switch 122 to^' the "extend" position. Upon switching, motor 214 causes actuating mechanism 216 to extend thereby pivoting pivot arm 210 about pivotal connection 212. The resulting motion causes wheel 118 to travel through an arc and be lowered towards the driving surface. Once wheel 118 contacts the driving surface, motor 214 continues to drive actuating mechanism 216 until the forward portion of frame 202 is lifted to a height sufficient to lift any forward drive wheels from the driving surface. To retract wheel 118, the user manipulable switch 122 is placed in the retract position and the opposite sequence occurs.

[0029] In this configuration, rear wheel drives 108 and 110 propel the vehicle instead of all of the wheel drives. This is advantageous because, in the two-wheel drive mode, only rear wheel drives 108 and 110 contact the driving surface, along with extendable wheel 118. Because only the rear wheel drives 108 and 110 drive the vehicle and extendable wheel 118 can pivot around a substantially vertical axis, the vehicle can have any turning radii. This provides for maneuvering "on the spot," which is very desirable for indoor use and other uses where turns may have to be made in a relatively small amount of space.

[0030] Whether in two or four (all) wheel drive mode, the center of gravity of the vehicle (both loaded and unloaded) is positioned well within the limits of the particular wheels or wheel drives that are contacting the driving surface. Hence, for the two-wheel drive mode, the center of gravity of the vehicle lies safely within the triangle formed by the rear wheel drives 108 and 110 and wheel 118. For the four-wheel drive mode, the center of gravity of the vehicle lies safely within the rectangle or quadrilateral formed by wheels or whe'el drives 108, 110, 112, and 114. [0031] The logic 104 of the present invention is generally illustrated in the flow chart of Figure 7. To recall, logic 104 controls the extending and retracting of supplemental in wheel assembly 116 and configures vehicle 200 in either two or four- wheel drive mode. In this regard, logic 104 is preferably implemented on a microprocessor or controller and resides in a memory associated therewith.

[0032] The logic commences in step 702 where the state (i.e., retract or extend) of user manipulable switch 122 is read. The state of switch 122 is only read in step 702 when the vehicle is at a standstill. Thus, changing the state of switch 122 while the vehicle is moving has no effect . This done for purposes of safety.

[0033] The logic next advances to step 704 where it determines which action to take based on the state of user manipulable switch 122. If the switch is in the "retract" position, then the logic advances to step 706. In step 706, the actuator assembly

(e.g., motor 214 and actuator mechanism 216) is engaged to raise or retract wheel 118. In this regard, the logic engages motor 214 causing actuating mechanism 216 to retract thereby pivoting pivot arm 210 about pivotal connection 212. The resulting pivotal motion causes wheel 118 to travel through an arc and rise away from the driving surface. Once wheel 118 reaches the limit of its motion, motor 214 and, thereby, actuator mechanism 216 are disengaged. The limits of motion of wheel 118 are preferably determined by limit switches (not shown) associated with actuating mechanism 216. These limit switches allow the limits of actuating mechanism's 216 linear motion to be variably defined and to provide a feedback as to when wheel 118 is in its extended or retracted state.

[0034] Once wheel 118 is retracted, all drive wheels are normally in contact with the driving surface and the logic proceeds to step 708. In step 708, the logic engages a four- wheel drive mode sub-logic. The four-wheel drive mode sub-logic preferably controls the driving action of all of the drive wheels. This sub-logic can be relatively simple such as, for example, driving all drive wheels that the same velocity. Conversely, the sub-logic can be relatively complex such as, for example, driving each drive wheel at its own individual velocity based on the speed and direction of vehicle 200. In this regard, many four-wheel drive control methods can be used, including those intermediate to the above-described examples. After step 708, the logic loops back to step 702 to again read the state of user manipulable switch 122.

[0035] However, if in step 704 switch 122 is in the "extend" state, then the logic proceeds to step 710. In step 710, the actuator assembly (e.g., motor 214 and actuator mechanism 216) is engaged to lower or extend wheel 118. In this regard, the logic engages motor 214 causing actuating mechanism 216 to extend thereby pivoting pivot arm 210 about pivotal connection 212. The resulting pivotal motion in this situation causes wheel 118 to travel through an arc and lower towards the driving surface . Once wheel 118 contacts the driving surface, motor 214 continues to drive actuating mechanism 216 until the forward portion of frame 202 is raised to a height sufficient to lift any forward drive wheels from the driving surface. In the illustrated embodiment, drive wheels 112 and 114 are lifted away from the driving surface. As described above, this height can be defined by the aforementioned limit switches. After step 710, the logic proceeds to step 712.

[0036] In step 712, the logic engages a rear-wheel drive (e.g., two-wheel drive) mode sub-logic. The rear-wheel drive mode sub-logic preferably controls the driving action of the rear drive wheels. In the present embodiment, this comprises a two- wheel drive mode sub-logic driving the two rear wheel drives 112 and 114. The rear-wheel drive mode sub-logic preferably drives each rear wheel drive at its own velocity based on the speed and direction of vehicle 200. In this manner, differences in rear wheel drive velocities are used to effect turns and turning radii. After step 712, the logic loops back to step 702 where the routine is repeated.

[0037] As already described, the aforementioned logic can be implemented as software running on a microprocessor or controller. However, it should also be noted that the logic can also be implemented on hybrid controller configurations wherein some portion of the logic is implemented with hard-wired circuitry and other portions as software. In this regard, the aforementioned logic can be implemented in any manner suited to the particular requirements of vehicle 200. The aforementioned logic can also reside alone a computer readable medium such as, for example, a Read Only Memory (ROM) , Compact Disc Read Only Memory (CD-ROM) , Programmable Read Only Memory (PROM) , Electrically Erasable Programmable Read Only Memory (EEPROM) , or other similar type memory devices .

[0038] While the present invention has been illustrated by the description of embodiments thereof, and while the embodiments have been described in considerable detail, it is not the intention of the applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. For example, the supplementary wheel assembly 116 can include more than one wheel or castor. Additionally, more than four wheel drives can be employed. Moreover, the location of various components of the present invention can be modified without affecting their function and purpose. Still further, a two-wheel drive controller and a four or all-wheel drive controller can be employed collectively with user manipulable switch 122 and/or the limit switches of supplemental wheel assembly 116 switching power or control between the two depending on whether two or four (all) wheel drive modes are desired. Therefore, the invention, in its broader aspects, is not limited to the specific details, the representative apparatus, and illustrative examples shown and described. Accordingly, departures can be made from such details without departing from the spirit or scope of the applicant's general inventive concept.

Claims

CLAIMS: I claim:

1. A multi-wheel drive vehicle comprising:

(a) a frame;

(b) at least two rear wheel drives attached to the frame;

(c) at least two wheel drives forward of the rear wheel drives and attached to the frame;

(d) at least one extendable and retractable wheel coupled to the frame forward of the rear wheel drives;

(e) logic for extending and retracting the at least one extendable and retractable wheel ; and (f) logic for adjusting the drive configuration of the vehicle such that the at least two wheel drives forward of the rear wheel drives are not configured to drive the vehicle when the at least one extendable and retractable wheel is in an extended position.

2. The vehicle of claim 1 further comprising logic for adjusting the drive configuration of the vehicle such that the at least two wheel drives forward of the rear wheel drives are configured to drive the vehicle when the at least one extendable and retractable wheel is in a retracted position.

3. The vehicle of claim 1 further comprising an actuator for extending and retracting the at least one extendable and retractable wheel .

4. The vehicle of claim 1 wherein the at least one extendable and retractable wheel is pivotally coupled to the frame.

5. The vehicle of claim 1 wherein the at least one extendable and retractable wheel is coupled to the frame via swivel assembly.

6. The vehicle of claim 1 wherein the at least one extendable and retractable wheel is disposed laterally between the at least two wheel drives forward of the rear wheel drives .

7. The vehicle of claim 1 wherein the at least two rear wheel drives are used for steering the vehicle when the at least one extendable and retractable wheel is in an extended position.

8. The vehicle of claim 3 wherein the at least one extendable and retractable wheel is pivotally coupled to a first location on the frame and the actuator is coupled to a second location on the rame .

9. A multi-wheel drive vehicle comprising:

(a) a frame means;

(b) a rear drive means attached to the frame; (c) a drive means forward of the rear drive means and attached to the frame means;

(d) wheel means extendable and retractable and coupled to the frame means forward of the rear drive means;

(e) means for extending and retracting wheel means; and (f) means for adjusting the drive configuration of the vehicle such that the drive means forward of the rear drive means are not configured to drive the vehicle when the wheel means is in an extended position.

10. The vehicle of claim 9 further comprising means for adjusting the drive configuration of the vehicle such that the drive means forward of the rear drive means is configured to drive the vehicle when the wheel means is in a retracted position.

11. The vehicle of claim 9 further comprising an actuator means extending and retracting the wheel means.

12. The vehicle of claim 9 wherein the wheel means is pivotally coupled to the frame means.

13. The vehicle of claim 9 wherein the wheel means is coupled to the frame via a swivel means .

1 . The vehicle of claim 9 wherein the wheel means is disposed laterally between the drive means forward of the rear drive means .

15. The vehicle of claim 9 wherein the rear drive means is used for steering the vehicle when the wheel means is in an extended position.

16. The vehicle of claim 11 wherein wheel means is pivotally coupled to a first location on the frame means and the actuator means is coupled to a second location on the frame means.

17. A multi-drive vehicle comprising: (a) a frame having a top portion and a bottom portion;

(b) at least two rear wheel drives coupled to the frame;

(c) at least two wheel drives forward of the rear wheel drives and coupled to the frame; and

(d) at least one extendable and retractable wheel assembly coupled to the frame forward of the rear wheel drives, the assembly comprising:

(1) an actuator pivotally coupled to the top portion of the frame;

(2) a pivot arm pivotally coupled to the bottom portion of the frame and the actuator; and

(3) at least one wheel coupled to the pivot arm.

18. The vehicle "of claim 17 further comprising logic for adjusting the drive configuration of the vehicle such that the at least two wheel drives forward of the rear wheel drives are not configured to drive the vehicle when the at least one extendable and retractable wheel assembly is in an extended position.

19. The vehicle of claim 18 further comprising logic for adjusting the drive configuration of the vehicle such that the at least two wheel drives forward of the rear wheel drives are configured to drive the vehicle when the at least one extendable and retractable wheel assembly is in a retracted position.

20. The vehicle of claim 17 wherein the at least one extendable and retractable wheel assembly further comprises swivel assembly coupling the at least one wheel to the pivot arm.