Interrelated power delivery controls – including engine control – Transmission control – Including fluid drive
Patent
1991-06-18
1995-05-23
Lorence, Richard M.
Interrelated power delivery controls, including engine control
Transmission control
Including fluid drive
477 65, 192 33, 747331, F16H 6114, F16H 4502
Patent
active
054176220
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a speed changing (shift change) system including a lock-up clutch by way of which input and output shafts of a torque converter are operatively connected to each other, wherein the technical improvement consists in that shock caused during speed changing or at the time of starting of forward movement of a vehicle is canceled, interruption of transmission of torque is prevented and cost for fuel consumption is reduced.
BACKGROUND ART
A conventional speed changing ( transmission ) unit is constructed such that the output shaft of an engine is connected to the input shaft of a torque converter and the input shaft of a transmission is connected to the output shaft of the torque converter, while a lock-up clutch is interposed between the input and output shafts of the torque converter so as to operatively connect them to each other via the lock-up clutch.
Such a lock-up clutch has the following five problems from the viewpoints of structure and control.
FIG. 25 is a hydraulic circuit diagram which illustrates a conventional control system for the lock-up clutch. This control system includes a lock-up clutch 4, a torque converter 2, a transmission tank 100, a strainer 101, a hydraulic pump 5, a main relief valve 102, a torque converter relief valve 103, a rear brake ring 104, an oil cooler 105, a plurality of oil filters 106, a cooling relief valve 107, a lubricating relief valve 108, a transmission lubricating section 109, a lock-up modulation valve 110 and a solenoid valve 120. The lock-up clutch 4 is controlled with respect to its operative engagement, disengagement from the operatively engaged state and gradual increasing of hydraulic pressure by operating the lock-up modulation valve 110 via the solenoid valve 120.
FIG. 26 is a schematic sectional view which illustrates by way of example the inner structure of such a conventional modulation valve 110 and solenoid valve 120 and FIG. 27 shows a plurality of characteristic diagrams for respective component each illustrating how characteristics vary during speed changing (i.e., shift change) as time elapses.
Specifically, with this control system, during speed changing, a lock-up "OFF" signal is first sent to a solenoid of the solenoid valve 120 (time t.sub.1). As a result, the solenoid valve 120 is brought in an opened state as shown in FIG. 25, whereby pilot hydraulic pressure set by the main relief valve 102 flows through the solenoid valve 120 to displace a piston 130 of the modulation valve 110 in the leftward direction. As the piston 130 displaces a spool 132 in the leftward direction via the piston 131, a port D which has been communicated with the lock-up clutch 4 is closed with the spool 132 and thereby hydraulic oil in the lock-up clutch 4 is drained.
Then, after a predetermined period of lock-up delay time for holding the lock-up clutch 4 in an OFF state elapses, a lock-up "ON" signal is sent to the solenoid of the solenoid valve 120 (time t.sub.2) . As a result, the solenoid valve 120 is shifted to a closed state so that working oil which has thrusted the piston 130 is drained via the solenoid valve 120. Thus, pressure of the working oil which has thrusted the piston 130 is reduced to a level of 0 Kg/cm.sup.2, causing the spool 132 to be displaced in the rightward direction by a spring 133 until the valve 110 is brought in an opened state. Consequently, main hydraulic oil flows in an order of A.fwdarw.C.fwdarw.D and is introduced into the lock-up clutch 4. After a filling time t.sub.f elapses, the lock-up clutch 4 is fully filled with hydraulic oil.
At this moment, hydraulic oil which has been introduced through the port D enters a hydraulic chamber 135 between the piston 131 and the spool 132 via an orifice 134 with the result that hydraulic pressure P.sub.v at an outlet of the valve is set to an initial pressure P.sub.o (=Kx/S.sub.1) under a condition that a force induced by hydraulic pressure active on a pressure receiving area S.sub.1 of the piston 131 is balanced with resilient force (kx, where K de
REFERENCES:
patent: 4671139 (1987-06-01), Downs et al.
patent: 5035312 (1991-07-01), Asayama et al.
Asayama Yoshio
Okura Yasunori
Sato Takayuki
Tsubota Makio
Kabushiki Kaisha Komatsu Seisakusho
Lorence Richard M.
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