IMPROVED TRACTION AND SUSPENSION CONTROL ASSEMBLY

Abstract: Enhanced traction control is provided in a modified 6x2 vehicle. An air suspension assembly is tied to the antilock/traction controller. Thus, in response to a differential traction control event, pressurized air to air bags associated with the suspension assembly is regulated to transfer greater vehicle load to the drive axle (10). This provides improved traction capability. If the drive axle is already at its rated maximum vehicle load, then no additional weight is transferred. In addition, isolation valves (72) are added to the brake lines associated with the non-drive axle (12). The isolation valves also communicate directly with the antilock/traction controller so that braking to the non-drive axle is isolated from the drive axle. This eliminates brake drag on the non-drive axle during a differential traction control event.

Description: IMPROVED TRACTION AND SUSPENSION CONTROL ASSEMBLY Background of the Invention This invention pertains to the art of traction control assemblies and more particularly, to a combined traction and suspension control assembly that provides 6x4 like traction performance on a 6x2 vehicle. The invention is particularly applicable to vehicles such as truck/tractor systems or buses and will be described with particular reference thereto. It will be appreciated, however, that the invention may have broader applications and may be advantageously employed in related environments or applications . Antilock/traction control assemblies are well known for truck and tractor systems. Particularly, a 6x4 system has a pair of drive axles, each necessarily including a drive mechanism and differential. Vehicle cost is higher in a 6x4 arrangement relative to a 6x2 arrangement because of the additional drive components. The increased costs can be on the order of $1,000. Additionally, there is a substantial increase in the weight associated with the additional drive assembly of a 6x4 vehicle. It is estimated that the additional drive components can add approximately 350 to 500 lbs. of weight. Further, a 6x4 system has increased operating costs. The increased complexity, maintenance costs, friction, and fuel consumption associated with an additional drive axle in a 6x4 assembly relative to a 6x2 assembly are all desirable reasons for using a 6x2 assembly; however, it does not have the improved traction capabilities associated with the 6x4 configuration . Traction control assemblies use the same general principles as an antilock braking system. That is, on wet surfaces, curves, split surfaces, and ice, traction control senses when the wheels of a vehicle spin upon acceleration, i.e., due to a loss of traction between the road surface and the tire. In order to compensate for this loss of traction, additional drive torque is transferred to the non-spinning tires or wheels. A braking force is gently applied to the spinning wheel which transfers the torque through the differential to the non-spinning, or more slowly spinning, wheel. If both wheels spin, then the engine RPM is electronically controlled and reduced to an appropriate level . In a 6x2 system, only one of the two rear axles is a drive axle. The non-drive axle, or tag axle or pusher axle, further distributes the vehicle load over an additional axle. In a traction control event the wheels associated with the non-drive axle may not even rotate. Because of the expenses associated with the second rear axle being driven in a 6x4 system, it is desired to use a non-drive axle (6x2) without loss of performance. It has been proposed to shift or transfer vehicle load in a 6x2 arrangement using an air bag suspension assembly that lifts the non-drive axle so that more weight can be transferred to the drive axle. This is a proportional weight transfer and there is a maximum limit to the load that can be transferred from the non-drive axle to the drive axle. In this manner, an increased portion of the load is transferred to the drive axle to enhance traction. Although these various known systems are each successful in their own right, they do not provide an automated traction control which combines both the traction control arrangement of a 6x4 vehicle in a 6x2 arrangement with increased traction associated with an adjustable, proportional weight transfer assembly that enhances traction control in response to a differential traction control event. Summary of the Invention The present invention contemplates a new and improved traction and suspension control assembly for a truck or tractor that overcomes the above-referenced problems and others and provides a simple, economical assembly that provides improved, effective, traction control in a simplified, reduced cost system. According to the present invention, a traction and suspension control assembly includes a drive axle and a non-drive axle. A traction control assembly associated with the drive axle selectively transfers torque in response to a differential traction control event. A suspension control assembly selectively transfers vehicle load from the non-drive rear axle to the drive rear axle in response to a differential traction control event. According to another aspect of the invention, the suspension control assembly is in fluid communication with the traction control assembly for automatically altering the vehicle load distribution in response to a differential traction control event. According to another aspect of the invention, the suspension control assembly includes a fluid chamber associated with each axle and a valve that regulates fluid flow from one chamber to the other for transferring vehicle load between the axles. According to yet another aspect of the invention, braking on the non-drive axle is isolated from the drive axle during a differential traction control event . According to a further aspect of the invention, the amount of vehicle load that may be transferred from the non-drive axle to the drive axle is limited. A principal advantage of the invention is the ability to obtain increased traction in a 6x2 system by modifying conventional traction control and air suspension assemblies, and tying the two together into a single integrated system. Another advantage of the invention is the automated nature of operation in response to a differential traction control event. Still another advantage of the invention is the ability to limit the amount of vehicle load that may be shifted from one axle to the other. Still other advantages and benefits of the invention will become apparent to those skilled in the art upon a reading and understanding of the following detailed description. Brief Description of the Drawings The invention may take physical form in certain parts and arrangements of parts, a preferred embodiment of which will be described in detail in this specification and illustrated in the accompanying drawings. The drawings include: Figure 1 is a schematic representation of a truck braking system. Figure 2 is a schematic representation of the new traction control arrangement that ties the air suspension assembly into the circuit of the antilock/traction assembly. Detailed Description of the Preferred Embodiment Referring now to the drawings wherein the showings illustrate the preferred embodiment of the invention only and do not limit the invention, the Figures show an improved traction and suspension control assembly A used on a truck or tractor to provide 6x4 like performance on a 6x2 system. More particularly, Figure 1 shows a tractor having tandem rear wheels 10, 12. The wheels 10 are connected together by a first or drive axle 14 of conventional structure. In a 6x2 system, one of the rear axles associated with the tandem wheels 10, 12 is a non-drive axle, here represented by the second or rear axle 12. Of course, it will be understood that the arrangement may be reversed without departing from the scope and intent of the subject invention. The tractor A shown in Figure 1 is equipped with a conventional antilock/traction control assembly B commercially available, for example, from the assignee of the present application. Briefly, the system includes an antilock modulator assembly 20 that controls braking to front wheels 22 of the tractor. In addition, an antilock/traction controller is incorporated into the pneumatic assembly so that air controls braking of the first and second axles also. During normal service operation, a series of sensors 26 provide representative signals of wheel spinning conditions to the control unit. If a wheel is spinning, i.e., a differential traction control event is sensed, braking is gently applied to the spinning wheel. This transfers torque to the non-spinning wheel through the differential as is well known in the art. Again, details of conventional antilock/traction control assemblies are well known in the art so further discussion herein is deemed unnecessary to a full and complete understanding of the present invention. Referring now to Figure 2, the schematic of the present invention is shown in greater detail. Again, a source of compressed air 28 is provided for the pneumatic assembly. It supplies air to an antilock/traction controller 30 which includes an antilock electronic control unit 32. The controller is also 30 equipped with traction solenoid valve 34 and relay valve 36. In this manner, pressurized air from the source 28 is controlled to modulator valves 38, 40 which supply the air brake actuators 42 associated with the rear wheels 10, 12. As briefly described above, o the sensors 26 are associated with the wheels 10 on the drive axle to monitor the rotation of the wheels. The non-drive axle wheels 12 do not include such sensors. Fluid lines 50, 52 extending from the modulators include first branches 50', 52' that supply the brake actuators associated with the drive axle. In addition, second branches 50' ' and 52' ' supply air to operate the brake actuators associated with wheels 12. In addition, an air suspension assembly 60 is provided for the drive and non-drive axle assembly. The air suspension assembly 60 includes fluid chambers or air bags 62, preferably discrete air bags, that shift or proportion the vehicle load between the drive and non-drive axles when inflated or deflated. As shown, the air bags 62 associated with the drive axle are commonly supplied through line 64 and communicate with a non-drive axle air suspension control valve 66. Likewise, the air bags 62 associated with the non-drive axle wheels are commonly supplied through a line 68 that extends from the non-drive axle air suspension control valve. In this manner, the air bags associated with the drive axle work in tandem and, similarly, the air bags associated with the non-drive axle work in tandem to shift the vehicle load as desired for enhanced traction. In addition, the tag axle air suspension control valve 66 is in fluid communication with the traction solenoid of the antilock/traction controller via line 70. This provides pressurized air from the source 28 as regulated by the antilock/traction controller 32, 34, 36 and supplies pressurized air to the control valve 66. Thus, if a differential traction control event occurs, pressurized air to the suspension control valve 66 is regulated. Moreover, isolation valves 72 are provided in the branch passages 52 ' ' associated with each brake actuator 42 of the non-drive axle. Thus, when a traction control event is encountered, air pressure provided from the antilock/traction controller through line 70 is directed to valves 72 to isolate the braking to the non-drive axle from the drive axle. In this manner, there is no brake drag on the non-drive axle during a differential traction control event. Accordingly, instead of having two drive axles, the system of the present invention uses a single drive axle 14. The single drive axle is used in combination with an air bag suspension assembly 60 on a non-drive axle, traction control 26, 38, 40 of the drive axle, and isolation valve 70 to separate control of the drive and non-drive axles . The non-drive axle helps carry the vehicle load during normal operation. If required, up to 50% of the load from the non-drive axle can be shifted to the drive axle, although it will not exceed this limit. No driver interface is necessary so that when a differential braking traction control event occurs, the present system dumps a portion of the air pressure in the non- drive axle suspension, thereby transferring weight to the drive axle and improving traction capability. If the drive axle is already at the maximum rated vehicle load, as determined by suspension pressure, no additional load will be transferred to the drive axle. Moreover, when the differential braking traction control event occurs, the braking to the non- drive axle is isolated from the drive axle so that no brake drag on the non-drive axle occurs . Thus as described above, by adding an additional port to the antilock/traction control unit and an additional three components (air suspension valve 66, and a pair of isolation valves) , a 6x2 vehicle is conveniently and economically modified to provide 6x4 type performance. The invention has been described with reference to the preferred embodiment. Obviously, modifications and alterations will occur to others upon a reading and understanding of this specification. It is intended to include all such modifications and alterations insofar o as they come within the scope of the appended claims or the equivalents thereof .

Claims: Claims : 1. A traction and suspension control assembly for a vehicle such as a truck, the assembly comprising: a drive axle; a traction control assembly for the drive axle selectively transferring torque to a wheel mounted on the drive axle in response to a differential braking traction control event; a non-drive axle; and a suspension control assembly operatively associated with the non-drive axle for selectively transferring vehicle load from the non-drive axle to the drive axle in response to a differential braking traction control event. 2. The assembly of claim 1 wherein the suspension control assembly is operatively connected to a controller of the traction control assembly. 3. The assembly of claim 2 wherein the suspension control assembly is connected to a traction application valve of the traction control assembly. 4. The assembly of claims 1-3 wherein the suspension control assembly includes a fluid chamber operatively associated with the non-drive axle for proportioning vehicle load carried by the drive and non-drive axles. 5. The assembly of claims 4 wherein the suspension control assembly includes a valve operatively associated with the fluid chamber for selectively controlling the fluid flow to and from the fluid chamber. 6. The assembly of claims 1-5 wherein the traction control assembly is operatively associated with the drive axle and is selectively isolated from the non-drive axle brakes in response to a differential traction control event. 7. The assembly of claims 1-6 wherein the traction control assembly is associated with an antilock braking assembly and braking on the non-drive axle is eliminated during a differential traction control event. 8. The assembly of claims 1-7 wherein the suspension control assembly includes drive and non- drive air suspension chambers operatively associated with the drive and non-drive axles, respectively, for proportioning vehicle load carried by the drive and non-drive axles, the air suspension chambers communicating with the traction control assembly through a regulating member so that vehicle load can be proportioned between the drive and non-drive axles in response to a differential traction control event. 9. The assembly of claims 1-8 wherein up to 50% of the vehicle load on the non-drive axle can be shifted to the drive axle. 10. An apparatus for achieving 6x4 like performance with a 6x2 three axle commercial vehicle comprising: a drive axle and a non-drive axle sharing a vehicle load; a traction control assembly operatively associated with the drive axle for selectively transferring torque from one wheel to another wheel mounted thereon in response to a differential traction control event; an air suspension assembly interposed between the drive and non-drive axles and the vehicle load; and an operative relay between the traction control assembly and the air suspension assembly for altering distribution of the vehicle load in response to a differential traction control event. 11. The apparatus of claim 10 further comprising a valve associated with the air suspension assembly for selectively regulating air flow thereto in response to the differential traction control event. 12. The apparatus of claims 10-11 wherein up to 50% of the vehicle load on the non-drive axle can be shifted to the drive axle. 13. The apparatus of claims 10-12 wherein the traction control assembly is operatively associated with the non-drive axle and is selectively isolated from the drive axle in response to a differential traction control event. 14. An interactive traction and suspension control assembly for a vehicle comprising: a drive axle having first and second wheels on opposite ends thereof; a non-drive axle having third and fourth wheels on opposite ends thereof; a sensor for monitoring the relative rotation of the first and second wheels; a control unit for receiving information from the sensor; a braking assembly operatively associated with the first, second, third, and fourth wheels and with the control unit, the braking assembly applying a braking force to one of the first and second wheels in response to a traction control event so that torque is transferred to the other of the first and second wheels and braking to the third and fourth wheels is isolated from the drive axle during a traction control event; and a suspension control assembly for supporting a vehicle load on the drive and non-drive axles, the suspension control assembly including first and second air chambers disposed between the drive axle and the vehicle load, and the non-drive axle and the vehicle load, respectively, the air chambers being in operative communication with one another so that a portion of the vehicle load can be shifted from the non-drive axle to the drive axle in response to a traction control event. 15. The assembly of claim 14 wherein up to 50% of the vehicle load on the non-drive axle can be shifted to the drive axle. 16. The assembly of claims 14-15 further comprising a control valve in fluid communication with the first and second air chambers and also in communication with the control unit.

Inventors: EBERLING CHARLES E, MCCLELLAND JAMES, MCCREIGHT DICK W, EBERLING, CHARLES, E., MCCLELLAND, JAMES, MCCREIGHT, DICK, W.
Applicants: ALLIED SIGNAL INC, ALLIEDSIGNAL INC.
Application year: 1999
Main classification: B60G17
IPC codes: B60G17, B60T8, B62D53