Fluid handling – Processes – Involving pressure control
Reexamination Certificate
2000-06-10
2001-10-30
Buiz, Michael Powell (Department: 3753)
Fluid handling
Processes
Involving pressure control
C137S487500, C137S557000
Reexamination Certificate
active
06308725
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to improvements to an actuator design and more particularly to improvements in an actuator design for use in automotive hydraulic fluid applications.
BACKGROUND ART
Hydraulic fluid applications are well known in the automotive industry. Two well known hydraulic fluid applications are automotive transmission systems and automotive braking systems. The pressure of the hydraulic fluid in such systems is commonly controlled and varied through the use of actuators. Hydraulic fluid pressure is known to be a vital element in the proper performance of such systems.
In an automotive automatic transmission system, electronic transmission controls are commonly used to control the pressure of the hydraulic fluid line. The pressure of the hydraulic fluid line can be used to control various elements of the automatic transmission system including the engagement of individual planetary gears. By engaging various combinations of planetary gears, an automatic transmission system accomplishes the same task as the shifting of gears in a manual transmission. Therefore, it is common within the art to refer to changes in the status of the planetary gear system as shifting gears or shift points even though the mechanisms are not commonly the same as those found in manual transmissions. It is known that the pressure of the hydraulic fluid line in automatic transmission systems can be used to control the shift points.
Known electronic automatic transmission systems often control the shift points based upon various factors including engine RPM, engine torque and vehicle speed. The electronic control unit (ECU) in these systems use the data from these factors to determine an optimal hydraulic fluid line pressure. Once the optimal hydraulic fluid line pressure is determined by the ECU, look-up tables within the ECU are accessed to determine the correct level of current to send to the actuator controlling the hydraulic fluid line pressure. These systems continue to monitor the data factors as well as the shift timing to determine if the correct hydraulic line pressure was achieved. If the data relayed to the ECU indicated that the correct hydraulic line pressure was not achieved, a new value is looked up in the tables and an “adapt” is recorded such that future adjustments are expedited. This system must continually zero in on the actual line pressure value, as it does not provide any way of monitoring the line pressure directly. This process of continually making adjustments is inefficient, may have a negative effect on the shift-feel quality of the transmission system and can have a negative effect on the fuel economy of the automobile.
In addition, it is known that in some existing systems, the “adapts” may not exceed 10 psi and therefore require the transmission to be occasionally recalibrated. Such a system is highly undesirable and can lead to customer dissatisfaction. It would therefore be desirable to have a transmission control system that would quickly, efficiently and consistently set the hydraulic fluid line to the correct pressure and thereby provide improved shift-feel quality and improved fuel economy and would minimize service requirements.
It is known that a similar system of hydraulic fluid line pressure control is utilized in some modern braking systems. These braking system use a traction control module (TCM) to adjust the brake fluid line pressure based upon various sensors that provide data relating to driving conditions. These braking systems do not monitor the actual pressure within the brake fluid line but rather provide approximations from look-up tables and continual adjustments to zero in on the actual line pressure value. Therefore, these systems share the same inefficiencies found in the above described automotive transmission systems.
Therefore, there is a need for an actuator that can quickly, accurately, and consistently set the line pressure in a hydraulic fluid line without the inefficiencies and maintenance requirements of known designs.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a smart actuator for use in hydraulic fluid systems that quickly, accurately, and consistently sets the line pressure in the hydraulic fluid line without the inefficiencies and maintenance requirements of known designs.
In accordance with the objects of this invention, a smart actuator is provided. The smart actuator includes a mounting base, a solenoid element and a pressure sensor element. The solenoid element and the pressure sensor element are attached to the single mounting base to create a smart actuator with a small profile that can be positioned within the small spaces often encountered in modern design requirements.
The smart actuator's solenoid element is in fluid communication with a hydraulic fluid line. The solenoid element is further in electrical communication with a remote control element. The control element sends electrical signals to the solenoid element to vary the pressure of the hydraulic fluid line.
The smart actuator's pressure sensor element is also in fluid communication with the hydraulic fluid line. The sensor element monitors the pressure of the hydraulic fluid line at a position located at the output of the solenoid element. The pressure sensor element is further in electrical communication with the remote control element. The pressure sensor element sends electrical signals to the remote control element to relay the actual pressure in the hydraulic fluid line. By relaying the actual pressure of the solenoid output to the remote control element, the solenoid element can be controlled to quickly and accurately bring the pressure of the hydraulic fluid line to the desired level.
A single wire harness is used to provide the electrical communication path between the remote control element to the solenoid element and the electrical communication path between the pressure sensor element and the remote control element. This provides additional space saving characteristics to the smart actuator.
Other objects and features of the present invention will become apparent when viewed in light of the detailed description of the preferred embodiment when taken in conjunction with the attached drawings and appended claims.
REFERENCES:
patent: 4796661 (1989-01-01), Hishinuma et al.
patent: 5404301 (1995-04-01), Slicker
patent: 5707039 (1998-01-01), Hamilton et al.
patent: 5836347 (1998-11-01), Harries
patent: 6003543 (1999-12-01), Sulatisky et al.
patent: 6116269 (2000-09-01), Maxson
Collins Duane Zedric
Lawlyes Daniel Alan
Buiz Michael Powell
Delphi Technologies Inc.
Funke Jimmy L.
Krishnamurthy Ramesh
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