Work vehicle

Abstract

There are provided an intake pressure detecting means for detecting an intake pressure on more downstream side than a throttle valve in an intake passage to an engine, a rotational speed detecting means for detecting a rotational speed of an engine, an engine controlling means for controlling the engine to arrive at a target air-fuel ratio corresponding to the detected intake pressure and the detected engine rotational speed and an abnormality treating means for executing an engine stopping treatment to stop the engine if an intake pressure higher than a set pressure has been detected and an engine rotational speed higher than a set rotational speed has been detected, when an opening degree state detecting means detects that the throttle valve is under a fully closed or substantially fully closed state.

Claims

1. A work vehicle comprising: a throttle valve incorporated in an intake passage to an engine and operable in response to an operation on an accelerator operational tool; an intake pressure sensor for detecting an intake pressure on more downstream side than the throttle valve in the intake passage; an engine rotation sensor for detecting a rotational speed of the engine; an engine control section program for controlling the engine based on a detection value of the intake pressure sensor and a detection value of the engine rotation sensor to arrive at a target air-fuel ratio corresponding to the detected intake pressure and the detected engine rotational speed; an opening degree sensor for detecting an opening degree state of the throttle valve; and an abnormality treatment section program for executing an engine stopping treatment to stop the engine if the intake pressure sensor detects an intake pressure higher than a set pressure and the engine rotation sensor detects an engine rotational speed higher than a positive set rotational speed, when the opening degree sensor detects that the throttle valve is under a fully closed or substantially fully closed state.

2. The work vehicle of claim 1, wherein the abnormality treatment section program executes, after execution of the engine stopping treatment, a reporting treatment for reporting abnormality to a driver by activating a meter panel.

3. The work vehicle of claim 1, wherein the abnormality treatment section program stops the engine by stopping fuel supply to the engine.

4. The work vehicle of claim 1, wherein the intake pressure sensor detects the intake pressure higher than the set pressure independently of the engine rotation sensor detecting the engine rotational speed as higher than the positive set rotational speed.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is an overall side view,

(2) FIG. 2 is a transmission system diagram,

(3) FIG. 3 is a control block diagram, and

(4) FIG. 4 is a flowchart of control operations.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(5) Next, an embodiment of a work vehicle relating to the present invention will be described with reference to the accompanying drawings.

(6) Incidentally, a front-rear direction in the following explanation of the embodiments is defined as follows, unless explicitly indicated otherwise. Namely, a direction denoted with an arrow F in FIG. 1 is defined as front side, and a direction denoted with an arrow B in FIG. 1 is defined as rear side, respectively.

(7) [General Arrangement]

(8) FIG. 1 shows a multi-purpose work vehicle as one example of work vehicle. Such multi-purpose work vehicle is configured as a vehicle that can be used for various purposes such as transport of load, a recreational activity, etc. This work vehicle includes a traveling vehicle body provided with a pair of left and right drivable and steerable front wheels 1 and a pair of left and right drivable rear wheels 2. At the center portion of the traveling vehicle body, there is provided a driving section 3 at which a driver will be seated and effect driving operations. At a rear portion of the traveling vehicle body, there is provided a load carrying deck 4 that can mount a load and can be operated for its dumping operation. Under the load carrying deck 4, an engine section 5 is provided.

(9) At the driving section 3, there are provided a steering wheel 6 for steering the front wheels 1, an accelerator pedal 7 (see FIG. 3) as an accelerator operational tool capable of manual operation of changing a traveling speed, a speed changer lever 8 for speed changing operation, a driver's seat 9 at which a person can be seated, and so on. The accelerator pedal 7 is configured to be capable of a foot step-on operation and to be urgingly returned to its initial position upon release of a foot therefrom. The speed changer lever 8 is configured to be switchable by a pivotal operation, to a forward first-speed position, a forward second-speed position, a neutral position and a reverse position.

(10) As shown in FIG. 2, the engine section 5 includes a gasoline engine (to be referred to shortly as engine hereinafter) E, and a speed changer device 10 for speed-changing output of the engine E and transmitting resultant speed-changed output to the front wheels 1 and the rear wheels 2. The speed changer device 10, though not specifically described herein, is capable of switching among a plurality of speed changed states having different speed changing ratios, by an operation on the speed changer lever 8. Specifically, the speed changing state of the speed changer device 10 can be switched among the forward first-speed state, the forward second-speed state, the neutral state and the reverse state. Under the neutral state, power transmission is disconnected, so the traveling vehicle body is set under a traveling stopped state. As shown in FIG. 2, power outputted from the speed changer device 10 is transmitted via a rear wheel differential mechanism 11 to the left and right rear wheels 2 and transmitted also to the left and right front wheels 1 via a front wheel differential mechanism 12.

(11) [Control Arrangement for Abnormality in Intake System]

(12) As shown in FIG. 3, a throttle valve 14 is provided for adjusting a supply amount of combustion air to a combustion air intake passage 13 for the engine E. The throttle valve 14 is operated in association with an operation of the accelerator pedal 7. Adjacent the throttle valve 14, there is provided an opening degree sensor 15 as an opening degree detecting means for detecting an opened state (actual opening degree) of the throttle valve 14.

(13) An intake pressure sensor 16 is provided as an intake pressure detecting means for detecting an intake pressure on more downstream side than the throttle valve 14 in the intake passage 13. An engine rotation sensor 17 is provided as a rotational speed detecting means for detecting an actual rotational speed of the engine E.

(14) At a portion of the intake passage 13 near the cylinders of the engine E, there is provided an injector 18 for feeding by injection fuel in the form of mist. A control device 19 is provided for controlling an output of the engine E by variably adjusting a fuel injection amount by the injector 18 for the engine E. The control device 19 is provided with a microcomputer. As shown in FIG. 3, the control device 19 includes a map storage section 20, an engine control section 21 as an engine controlling means, and an abnormality treatment section 22 as an abnormality treating means. The engine control section 21 and the abnormality treating section 22 are configured as control programs of the control device 19. Alternatively, however, the engine control section 21 and the abnormality treatment section 22 can be configured as an electronic circuit device having these sections distinctly. In the drawing, a numeral 24 denotes an ignition plug.

(15) In the map storage section 20, there are recorded and stored in advance, in the form of map data, relationships between intake pressures corresponding to respective operational amounts of the accelerator pedal 7 and engine rotational speeds corresponding respectively to these intake pressures. Referring further briefly to the map data, in the map data, various control information is stored in the form of map with correlating the intake pressures and the engine rotational speeds. This map data can alternatively be configured such that air-fuel ratio data corresponding to a plurality of operational points on the map or ignition timing data corresponding to a plurality of operational points on the map are set in correlation with the map data in advance.

(16) The engine control section 21 controls an operation of the injector 18, based on the map data, in such a manner that an actual air-fuel ratio of the engine E may arrive at a target air-fuel ratio corresponding to the intake pressure and the output rotational speed, thus adjusting a fuel injection amount for the engine E. More particularly, the engine control section 21 inputs detection information of the intake pressure sensor 16 and detection information of the engine rotation sensor 17 and sets a target air-fuel ratio corresponding to the detected value of the intake pressure sensor 16 and the detected value of the engine rotation sensor 17, from the map data. And, the engine control section 21 controls a fuel injection amount for the engine E by controlling the operation of the injector 18, so as to arrive at the target air-fuel ratio.

(17) As shown in FIG. 4, the abnormality treatment section 22 inputs detection information of the opening degree sensor 15, detection information of the intake pressure sensor 16 and detection information of the engine rotation sensor 17. And, if the intake pressure sensor 16 detects an intake pressure higher than a set pressure (step 2) and the engine rotation sensor 17 detects an engine rotational speed higher than a set rotational speed (step 3), when the throttle opening degree sensor 15 detects that the throttle valve 14 is under a fully closed or a substantially fully closed state, then, the abnormality treatment section 22 executes an engine stopping treatment for stopping operation of the engine E by stopping fuel supply to the engine E by the injector 18 (step 4).

(18) As such set pressure for abnormality determination in the intake pressure, this is set as such an intake pressure as not leading to erroneous abnormality determination when the engine E is operating normally even if there occurs a change in the temperature of the engine E due to a certain operational condition or a change in the atmospheric pressure to an altitude difference.

(19) The abnormality treatment section 22 acts as a reporting means simultaneously with the execution of the engine stopping treatment to effect a reporting operation for reporting the abnormality to the driver by causing an error code and an alarm lamp to be displayed on a meter panel 23 provided in the driving section 3 (step 5). Such reporting treatment can be any that can cause the driver to recognize the abnormality.

(20) If the intake pressure and the engine rotational speed are high although the throttle valve 14 is under the fully closed or substantially fully closed state, then it may be assumed that a certain abnormality exists such as presence of damage in the midst of the intake passage 13, presence of a gap at a connecting portion of pipes, etc. Then, in such case, an emergency stop of the engine E is effected and also this is reported by the error code and the alarm lamp on the meter panel 23. With this, it is possible to avoid re-occurrence of abnormality such as excessive rise in the engine rotational speed by restart of the engine.

Other Embodiments

(21) (1) In the foregoing embodiment, as the reporting means, there are provided an error code and an alarm lamp to the meter panel 23. In place of this arrangement, reporting by means of an alarm buzzer or the like can be made. Or, the meter panel 23 and the alarm buzzer can be employed in combination as well.

(22) (2) In the foregoing embodiment, the engine E is stopped by stopping fuel supply. Alternatively, the engine E can be stopped by stopping the operation of the ignition plug 24.

(23) (3) In the foregoing embodiment, the accelerator pedal 7 is employed as the accelerator operational tool. Instead, a manual operation type accelerator lever may be employed.

(24) (4) In the foregoing embodiment, a gasoline engine is employed as the engine E. Instead, a diesel engine may be employed.

(25) (5) In the foregoing embodiment, the traveling vehicle body has the front wheels 1 and the rear wheels 2. Instead, a crawler type traveling device can be employed as the traveling device.

INDUSTRIAL APPLICABILITY

(26) The present invention is applicable not only to a multi-purpose work vehicle, but to various work vehicles such as a tractor, a combine, etc.