System and method of driving and controlling pneumatic and hydraulic systems

Systems and methods of driving and controlling pneumatic and hydraulic devices and, more particularly, to a system and method of driving a hydraulic pump via one output shaft of a motor, and driving a pneumatic compressor via another output shaft of the motor via a clutch. When a user control is engaged, a control system causes the motor to operate at a higher speed, driving the hydraulic pump faster to produce additional hydraulic pressure. When a low air pressure condition is sensed in the pneumatic system, the control system causes the motor to operate at the higher speed and engages the clutch, allowing the pneumatic compressor to supply additional air pressure.

FIELD OF INVENTION

The present invention relates generally to systems and methods of driving and controlling pneumatic and hydraulic devices and, more particularly, to a system and method of driving a hydraulic pump via one output shaft of a motor, and driving a pneumatic compressor via another output shaft of the motor via a clutch. When a user control is engaged, a control system causes the motor to operate at a higher speed, driving the hydraulic pump faster to produce additional hydraulic pressure. When a low air pressure condition is sensed in the pneumatic system, the control system causes the motor to operate at the higher speed and engages the clutch, allowing the pneumatic compressor to supply additional air pressure.

BACKGROUND

Many machines produced today utilize pneumatic and hydraulic systems to power various systems. For example, terminal tractors are specialty vehicles which are used to move semi trailer equipment from point to point around a yard. One type of terminal tractor utilizes a hydraulically activated “5th wheel”—essentially a horseshoe shaped coupling device into which the coupling pin of a trailer is attached. When a trailer is not coupled to a vehicle, it generally stands on static supports at its front, and on wheels at its back. When a trailer is engaged with and coupled to a vehicle having a 5th wheel, hydraulic cylinders lift the 5th wheel via a boom to raise the front of the trailer off of its front supports. In this way, the vehicle can move the trailer.

In current terminal tractors, hydraulic pressure is generated from a hydraulic pump driven by a combustion engine. Generally, when the 5th wheel of a terminal tractor engages a trailer, the terminal tractor is stationary and the engine is therefore idling. At idle speeds, standard motors generally produce sufficient hydraulic pressure to power the hydraulically assisted steering of the tractor, but may not produce sufficient pressure to extend the 5th wheel boom to lift a heavy trailer. As such, workers will often rev the engine during such 5th wheel lifts, causing the engine to operate at a higher rpm than its idle speed. This causes hydraulic pumps within the vehicle to pump faster, producing substantially more hydraulic pressure which allows the 5th wheel to extend and support a trailer. Some vehicles require the operator to step on both the accelerator and the brake at the same time to accomplish a higher motor rpm level, which can harm the vehicle.

Additionally, in current terminal tractors, pneumatic pressure is generated from an air compressor which is powered by a motor. Pneumatic pressure is often utilized in braking systems of such vehicles. As air pressure it utilized to apply brakes, the air compressor is engaged to supply additional pressure. However, as above with the hydraulic systems, there are times that additional power is needed to supply adequate air pressure in many vehicles.

Thus, there is a need for an improved system and method for driving and controlling pneumatic and hydraulic systems, in which vehicle motors are controlled so as to output sufficient power to drive pneumatic and hydraulic systems as needed.

SUMMARY OF THE INVENTION

The present invention provides a vehicle power system which may preferably be used in a terminal tractor. The system includes a variable speed motor having first and second output shafts, which motor normally operates in a standard RPM mode. A hydraulic pump is connected to and powered by the first output shaft, and a first number of gallons per minute (GPM) of hydraulic fluid flow from said hydraulic pump, and preferably four GPM, is diverted to power a first vehicle system, which is preferably a power steering system. The remaining GPM of hydraulic fluid flow is directed to power a second vehicle system, which is preferably a 5th Wheel system. Thus, the motor powers the hydraulic pump, which in turn provides hydraulic pressure for the power steering and 5th Wheel operation of a terminal tractor. Additionally, a pneumatic compressor is connected to the second output shaft by a clutch, which selectively engages the second output shaft to the pneumatic compressor to power the pneumatic compressor. The clutch engages the second output shaft with the pneumatic compressor when low air pressure is detected in a pneumatic system, which is preferably a braking system. Thus, the motor powers the pneumatic compressor to replenish air pressure for the braking system when low air pressure is detected in the braking system.

Additionally, a user control is operable to initiate a high RPM mode of the motor, which high RPM mode causes the motor to operate at a higher RPM than does the standard RPM mode. For example, in one embodiment, in the standard RPM mode, the motor may operate at between approximately 500-RPM and 1000-RPM, while the motor may operate at between approximately 1700-RPM and 2200-RPM in the high RPM mode. More preferably, the motor may operate at approximately 1000-RPM in the standard RPM mode, while operating at approximately 2000-RPM in the high RPM mode. In doing so, the high RPM mode increases the power provided to the hydraulic pump, in turn causing the hydraulic pump to generate more hydraulic pressure. As the first number of GPM diverted to the first vehicle system preferably remains constant despite the overall increase in hydraulic fluid flow pumped by the hydraulic pump (and therefore the increased hydraulic pressure in the hydraulic system), the hydraulic pressure provided to the second vehicle system is thereby increased. Thereby, the user control allows an operator to cause the system to provide added power to the second vehicle system when so directed.

Another embodiment of the present invention provides for a method of powering vehicle systems. Such method includes running a variable speed motor in a standard RPM mode, and powering a hydraulic pump by a first output shaft of the motor. A first number of GPM of hydraulic fluid flow is then diverted to power a first vehicle system, while the remaining hydraulic fluid flow is directed to power a second vehicle system. When a user control is actuated, the motor is run in a high RPM mode to increase the GPM output by the hydraulic pump to provide additional hydraulic power to the second vehicle system. Additionally, air pressure is monitored in a pneumatic system, and a pneumatic compressor is connected to a second output shaft of the motor via a clutch to power the compressor when a low air pressure condition is detected.

DETAILED DESCRIPTION

The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the various embodiments of the present invention, its applications, or uses.

Although the systems and methods of driving and controlling pneumatic and hydraulic systems described herein are preferably used in connection with terminal tractors, their uses are not so limited and it is recognized and anticipated that the present systems and methods can be utilized in a wide variety of different vehicular and non-vehicular applications as will be hereinafter evident. With respect to the reference numbers used in the drawings, like numerals refer to like parts.

As seen inFIG. 1, a motor10, which is preferably a variable speed motor but which may be a dual speed motor, is provided. Motor10may itself be an internal combustion motor, or may be an electric motor powered by an electrical system such as that in a hybrid vehicle. Motor10has a first output shaft15, which is connected to a hydraulic pump20. As motor10operates, it drives output shaft15, which in turn powers hydraulic pump20. Preferably, motor10drives hydraulic pump20continuously while motor10is in operation. Hydraulic pump20thereby supplies hydraulic pressure to various vehicle systems, as will be discussed in detail below in connection withFIG. 2.

Motor10also has a second output shaft40, which engages a pneumatic compressor50via clutch45. When clutch45engages output shaft40with pneumatic compressor50, motor10drives output shaft40, which in turn powers pneumatic compressor50. When clutch45disengages output shaft40from pneumatic compressor50, motor10drives output shaft40, but does not power pneumatic compressor50. As a result, clutch45engages only when pneumatic compressor50is needed to supply additional air pressure to various vehicle systems, such as vehicle braking system65.

Pneumatic compressor50, when driven by motor10via output shaft40and clutch45, compresses ambient air, which compressed air is then directed to and stored within high-pressure reservoir60for use by braking system65as needed. It will be understood that other vehicle systems may utilize pneumatic pressure as well by drawing stored compressed air from reservoir60. Air pressure within reservoir60is detected by air pressure sensor70, which signals clutch45to engage output shaft40with the pneumatic compressor50when air pressure in the reservoir60is depleted to a certain level. As a result, motor10drives pneumatic compressor50via output shaft40and clutch45to replenish air pressure within reservoir60when air pressure sensor70detects low air pressure within reservoir60. However, when sufficient air pressure is detected within reservoir60, clutch45is disengaged so that motor10does not drive pneumatic compressor50to increase air pressure within the pneumatic system.

As mentioned above, motor10also drives hydraulic pump20via output shaft15. As hydraulic pump20is driven by motor10, hydraulic fluid (and therefore hydraulic pressure) is provided to various vehicle systems. As best shown inFIG. 2, such vehicle systems are shown as a power steering system30and a 5th Wheel system35, as would be the case in a terminal tractor. However, it should be recognized that other types of hydraulic systems could be similarly utilized. Power steering system30may require only a fraction of the overall hydraulic fluid flow and pressure generated by hydraulic pump20. For example, the power steering system30can require about 4-6 gallons per minute (GPM) of hydraulic fluid flow to allow sufficient steering control over a terminal tractor.

As such, the remaining GPM of hydraulic fluid flow from hydraulic pump20can be selectively diverted to other vehicle systems which require hydraulic pressure, such as a 5th Wheel system35. InFIG. 2, hydraulic fluid flow is illustrated as being controlled by a simple valve28which directs a portion of hydraulic fluid flow through either hose24to the power steering system30, or through hose26to the 5th Wheel system35. It is noted that the specific configuration and design of valve28is not limited to that shown inFIG. 2. Valve28may be a spring-plate value, a swash-plate valve, an electronically controlled valve or any other valve capable of diverting hydraulic fluid flow to the power steering system30and 5th Wheel system35as described above. In any case, in a preferred embodiment, valve28is positioned relative to the overall hydraulic fluid flow being pumped by hydraulic pump20to allow a first number of GPM, and more preferably approximately 4-6 GPM, of hydraulic fluid flow to the power steering system30regardless of the overall amount of hydraulic fluid flowing into valve28, selectively diverting the remaining hydraulic fluid flow to the 5th Wheel system35.

In normal operation, motor10operates in a standard RPM mode, which is preferably a mode in which motor10operates at an idle speed. In standard RPM mode, motor10drives hydraulic pump20to pump a first amount of hydraulic fluid, thereby creating a first amount of hydraulic pressure. As discussed above, a first number of GPM are then directed to a first vehicle system, such as directing approximately 4-6 GPM to the power steering system30, while the remaining GPM are directed to the 5th Wheel system35. However, as would be understood by one of ordinary skill in the art, some vehicle systems, such as 5th Wheel system35, require substantially more hydraulic pressure during certain load-intensive activities than at other times. For example, the 5th Wheel system35of a terminal tractor may require essentially no or little hydraulic pressure when disconnected from a trailer. However, upon engaging a trailer with the 5th Wheel, terminal tractors need substantially increased hydraulic pressure to lift the trailer from its front supports so as to be able to move the trailer as needed. When motor10is operating in its standard RPM mode, the amount of hydraulic pressure generated by hydraulic pump20may be insufficient to allow the 5th Wheel system35to lift such a trailer.

Therefore, a user control80(FIG. 1) is provided which can be toggled to initiate a high RPM mode in motor10in which motor10operates at an increased speed. When user control80is engaged, the high RPM mode of motor10causes output shaft15to increase its RPM, thereby driving hydraulic pump20to pump additional hydraulic fluid and generate added hydraulic pressure. Further, since valve28ensures that only a first number of GPM of hydraulic fluid, and preferably 4-6 GPM, flows to the power steering system30even during the high RPM mode, substantially all of the increased GPM of hydraulic fluid flow is then directed to the 5th Wheel system35. This allows the 5th Wheel system35to lift trailers which could not be lifted with the hydraulic pressure generated when motor10is operating in standard RPM mode.

It is noted that air pressure sensor70may also initiate high RPM mode in motor10, along with engaging clutch45, when air pressure sensor detects low air pressure in reservoir60. As can be seen, when user control80induces the high RPM mode in motor10, pneumatic compressor50is not necessarily driven with increased power, or at all, unless clutch45engages the pneumatic compressor50with output shaft40. However, where air pressure sensor70initiates the high RPM mode in motor10and engages clutch45to cause an increase in air pressure in reservoir60, motor10will also drive hydraulic pump20with increased power, whether or not the hydraulically powered vehicle systems30,35require additional hydraulic pressure. In such a situation, the additional flow of hydraulic fluid pumped by the hydraulic pump20may be dumped back into a hydraulic fluid reservoir (not shown).

Referring now toFIG. 3, a flow chart of a method of controlling pneumatic and hydraulic systems100according to one embodiment of the present invention is show. At step110, the motor10is set to operate in standard RPM mode, and clutch45is disengaged. At step120, a check is made to determine whether user control80has been activated. If user control80has been engaged, the high RPM mode of motor10is initiated at step130to cause an increase in hydraulic pressure generated by hydraulic pump20. At step140, a check is made to determine whether reservoir60contains low air pressure. If not, the clutch is disengaged (if engaged) or remains unengaged (if not engaged) at step145, and method returns to step120. If low air pressure is detected at step140, the clutch45is engaged at step160, causing pneumatic compressor50to replenish the air pressure in reservoir60. The method then returns to step120.

If, at step120, the user control has not been activated, a check is made to determine whether reservoir60contains low air pressure at step125. If low air pressure is detected at step125, the high RPM mode is initiated in motor10at step135. This has the side affect of causing hydraulic pump20to increase the GPM of hydraulic fluid being pumped, and therefore at step150such additional hydraulic fluid flow is dumped into the hydraulic fluid reservoir. At step160, clutch45is then engaged to allow motor10, operating in the high RPM mode, to drive pneumatic compressor50to replenish the air pressure in reservoir60.

It is noted that when pneumatic compressor50is engaged with motor10, the pneumatic pressure generated by the compressor50when motor10is operating in standard RPM mode may be sufficient to replenish the air pressure in reservoir60without the need for motor10to operate in the high RPM mode. As such, in an alternate embodiment, at step125when low air pressure is detected in reservoir60, step135may be skipped such that the motor10continues to operate in standard RPM mode. In that circumstance, step150may also be skipped, as there may be little or no extra hydraulic fluid flow to dump. As such, where low air pressure is detected at step125, the method may advance directly to step160where clutch45is engaged.

Thus, there has been shown and described several embodiments of a system and method of driving and controlling pneumatic and hydraulic systems for use in association with various vehicles, which fulfill all of the objects and advantages sought therefore. As various modifications could be made to the exemplary embodiments as described above with reference to the corresponding illustrations without departing from the spirit and scope of the present invention, it is intended that all matter contained in the foregoing description and shown in the accompanying drawings shall be interpreted as illustrative rather than limiting. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the above disclosures, their equivalents, and the claims which follow.