Motor vehicles – With means for detecting wheel slip during vehicle...
Patent
1990-06-15
1994-03-29
Focarino, Margaret A.
Motor vehicles
With means for detecting wheel slip during vehicle...
172 3, 36442407, 3644241, 36442603, B60K 4100
Patent
active
052976491
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates generally to a crawler type tractor, e.g., a bulldozer having a blade, a ripper or the like attached thereto to perform a bulldozing operation, a ripping operation or the like. More particularly, the present invention relates to an apparatus for controlling an output from an engine installed on the crawler type tractor wherein the engine output is automatically controlled in an optimum manner based on a shoe slip at the time of starting movement of the vehicle (crawler type track), at the time when the vehicle is held in a neutral state or at the time when the vehicle is held in a three-point grounding state.
BACKGROUND ART
Generally, a crawler type tractor, e.g., a bulldozer or the like vehicle runs such that an output from an engine installed on the vehicle is transmitted to sprockets via a power line comprising a torque converter, a speed changing unit, bevel gears, a steering clutch, a steering brake and a final speed reduction unit and thereby track shoes extending round the sprocket wheels are driven.
On the other hand, a target engine speed of the engine on the crawler type tractor is set to a predetermined value by a throttle lever. Once the target engine speed is set, an output torque generated by the engine is controlled to reach the target engine speed by controlling a quantity of fuel to be injected. Usually, the crawler type tractor is equipped with a deceleration pedal so that the engine output can be reduced to a value corresponding to an extent of depressing of the deceleration pedal which has been depressed by an operator.
Tractive power generated by the engine during running of the crawler type tractor is related to a shoe slip rate representative of shoe slip appearing between the track shoes and the ground surface. As the shoe slip increases, the tractive power increases correspondingly, until the shoe slip rate reaches a predetermined limit value. However, if the shoe slip rate exceeds the predetermined limit value, the track shoes are uselessly caused to slip with the result that an engine output from the engine on the crawler type tractor fails to be effectively utilized as a tractive power. This leads to not only loss of energy but also wear of the track shoes within a short period of time.
Hitherto, e.g., when shoe slip occurs due to increased load during a soil heaping operation with the use of a blade or during a ripping operation with the use of a ripper unit attached to the bulldozer, an operator senses an occurrence of shoe slip and depresses the deceleration pedal to reduce the engine output. At the same time, he actuates a working unit actuating lever to alleviate the engine load to lower the tractive power. In other words, a problem arising due to an occurrence of shoe slip has been heretofore eliminated by the aforementioned complicated actuations which require a highly trained skill.
However, since a controlling operation for adequately compensating the shoe slip by an operator's actuation has been performed by sensing of the shoe slip, depressing of the deceleration pedal with his foot and actuating of levers for working units with his hand, he feels complicated and moreover he is required to pay close attention to his actuations. In practice, since he reduces an output from the engine after an occurrence of shoe slip, it is unavoidable that the shoe slip lasts for a certain period of time. In addition, some operators often cause useless slip due to careless inattention. In this case, it may be impossible to completely prevent an occurrence of such shoe slip. Particularly, when the bulldozer collides against a hard rock-bed during a ripping operation, the result is that the rear part of a vehicle body is raised up without piercing of a ripper into the rock-bed so that the bulldozer is brought in a three-point grounding state wherein the vehicle body comes in contact with the ground surface at three points, two of them being located at the fore parts of both crawler belts and the other one being located at the foremost end
REFERENCES:
patent: 880061 (1908-02-01), Anderson
patent: 4344499 (1982-08-01), van der Lely
patent: 4402377 (1983-09-01), Brooks
patent: 4454919 (1984-06-01), Arnold et al.
patent: 4626040 (1986-12-01), Ogino
patent: 4807132 (1989-02-01), Arai et al.
patent: 4933857 (1990-06-01), Hashiguchi et al.
Yamada Hideki
Yamamoto Shigeru
Boehler A. M.
Focarino Margaret A.
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