Interrelated power delivery controls – including engine control – Transmission control – Transmission controlled by engine
Patent
1993-05-26
1996-01-16
Lopez, F. Daniel
Interrelated power delivery controls, including engine control
Transmission control
Transmission controlled by engine
60406, 91 1, 137554, 13759616, 477906, F16H 6112
Patent
active
054843529
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a detector switch for confirming that a control valve spool, for switching the speed of the transmission of automobiles or construction machines or the like, is operating.
BACKGROUND ART
Conventionally, in a transmission having a clutch with N speed stages, a control valve 21 is constructed, as shown in FIGS. 4 and 5, such that the N number of spools 22 and electromagnetic valves (not shown) are arranged so that each is connected to a corresponding clutch. An electrical signal is transmitted to the electromagnetic valves, and the spools 22 are switched by pilot pressure, thus changing the speed stages.
More specifically, when an electromagnetic valve is turned ON, the pilot pressure acts on the spool 22 against the force of a spring 23 so as to urge the spool to the right, as illustrated in FIG. 4. The hydraulic pressure from a pump (not shown) passes through the control valve 21 from a pump port 24 to a clutch port 25 and is transferred to a clutch (not shown), thus turning the clutch ON.
On the other hand, when an electromagnetic valve is turned OFF, the pilot pressure is reduced to nothing, and thus the spool 22 is pushed to the left by the force of the spring 23, as shown in FIG. 5. The hydraulic pressure of the clutch (not shown) passes through the control valve 21 from the clutch port 25 to a drain port 26 and is drained to an oil tank (not shown), thus turning the clutch OFF. It should be noted that a throttle 27 is arranged so that it communicates with the oil tank when an electromagnetic valve is OFF.
However, in such a conventional construction, when a signal is transmitted from the controller for switching an electromagnetic valve, the controller is not capable of detecting whether or not the spool is switched in response to the signal, thus causing the following problems.
(1) For instance, in a transmission including a low stage clutch and a second stage clutch, although an OFF signal is transmitted to the low stage electromagnetic valve and an ON signal is transmitted to the second stage electromagnetic valve for switching the transmission from low to second, the low stage spool is not always switched.
The reason can be, for example, that the spool or the electromagnetic valve is blocked with dust, or is stuck. In this case, the low stage clutch and the second stage clutch are both engaged, and thus the transmission is damaged.
(2) For example, although an ON signal is transmitted to the low stage electromagnetic valve, the spool is not operated due to a failure of the electromagnetic valve, and the low stage clutch is not turned ON. Even in this case, since the controller is not capable of recognizing an abnormality of the electromagnetic valve, it is necessary to manually operate a spool (hereinafter referred to as an emergency escape spool), which is capable of turning ON and OFF without employing the electromagnetic valve, when the failure is detected. It also takes time to carry out the emergency escape.
SUMMARY OF THE INVENTION
In view of the foregoing problems, it is an object of the present invention to provide a detector switch for detecting the operation of a control valve spool, which switch is capable of confirming that an electrical signal to an electromagnetic valve has been transformed into the operation of the spool, thus overcoming the drawbacks of the conventional art.
To achieve the above object, the present invention provides a detector switch for detecting the operation of a valve spool of a transmission control valve, the detector switch being fixed to an end of a valve member in the vicinity of an end of the control valve spool, and a controller for turning ON and OFF an electromagnetic valve connected to the control valve in order to change the hydraulic pressure in a transmission clutch, characterized in that the detector switch is capable of transmitting a signal to the controller when the control valve spool abuts against the detector switch in order to confirm that an electrical signal transmitted to the
REFERENCES:
patent: 3741244 (1973-06-01), Ise
patent: 3896280 (1975-07-01), Blake
patent: 4567791 (1986-02-01), Sato
patent: 5021955 (1991-06-01), Ito et al.
Kabushiki Kaisha Komatsu Seisakusho
Lopez F. Daniel
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