Patent Application
20170016209
This application claims priority to Japanese Patent Application No. 2015-142179 filed Jul. 16, 2015, the disclosure of which is hereby incorporated in its entirety by reference.
1. Field of the Invention
The present invention is directed to a work vehicle adapted to mount a front work implement operated under a forward facing posture and a rear work implement operated under a reverse facing posture.
2. Description of the Related Art
U.S. Pat. No. 6,851,495 B2 discloses a work vehicle operated by a driver seated under a forward facing posture. This work vehicle includes a direction switch for selecting a forward traveling and a reverse traveling; and a lever operational tool for adjusting a creeping speed. At a time of a work using a backhoe mounted at a vehicle body rear portion, a driver can use the direction switch and the lever operational tool to cause the vehicle body to travel forwardly or reversely at a desired speed. The direction switch is a a seesaw type momentary switch, and its selected operational position is transmitted to a control device. An operational position of the lever operational tool is detected by a potentiometer and transmitted to the control device. The driver will operate the direction switch to an operational position corresponding to a desired traveling direction, and also will operate the lever operational tool to a desired speed position. Then, the control device causes the vehicle body to travel in the direction (forward or reverse) based on the direction switch at the speed based on the operational position of the lever operational tool.
JP2008-056022A discloses a tractor in which a driver seated under a reverse facing posture can cause it to travel either forwardly or reversely, by operating a main switch and a sub switch constituting a shuttle switch at one time. The main switch includes a forward switch and a reverse switch that are disposed in close vicinity of each other. When it is desired to cause the vehicle body to travel forwardly or reversely with the driver being seated under the reversely facing posture, the driver will operate one of the forward and reverse switches and the sub switch simultaneously.
Forward/reverse traveling operations under the reverse facing posture are “special” operations in comparison with forward/reverse traveling operations under the forward facing posture, so it is desired that these forward/reverse traveling operations under the reverse facing posture should be simple operations. Further, a control scheme reflecting a driver's intension distinctly will also be desirable. However, with the above-described conventional state of art, there are provided two switches for the forward/reverse traveling operations under the reverse facing posture, and these switches are provided independently of each other and spaced apart from each other. Thus, for effecting forward or reverse operations under the reverse facing posture, independent operations corresponding respectively to the two switches are required for the driver. Moreover, respecting a time-sequence operation procedure for the plurality of switches, explicit disclosure relating thereto found in JP2008-056022A only discloses that the plurality of switches are operated simultaneously.
In view of the above-noted state of art, there is a need for a work vehicle that allows forward/reverse operations under the reverse facing posture to be effected in a more distinct manner, that is, through a time-sequence operational procedure with the driver's distinct awareness thereof and also in a more simple manner.
According to one aspect of the disclosure, a work vehicle is provided as under.
A work vehicle adapted to mount a front work implement operated under a forward facing posture and a rear work implement operated under a reverse facing posture, the work vehicle comprising:
With the above-described arrangement, when a driver carries out a forward/reverse operation, the driver can easily carry out this operation with using his/her one hand only.
According to another aspect of the disclosure, the signal evaluating section is configured to output the traveling command for causing the vehicle body to travel forwardly or reversely, based on an input of the second operational signal under an inputting state of inputting the first operational signal. With this, when the driver is to effect a forward/reverse operation of the vehicle body under the driver's rear facing posture, the driver can effect this forward/reverse operation by operating the second operational tool under a state of the first operational signal based on an operation on the first operational tool being inputted to the traveling control unit. Namely, for forward or reverse traveling of the vehicle body, an operation on the first operational tool needs to be effected prior to an operation on the second operational tool. In this way, by providing time-sequential conditions to the operations on the first operational tool and the second operational tool, it becomes possible to realize a forward/reverse control scheme that allows clear recognition or awareness of the intension of the forward/reverse operation of the driver under the reverse facing posture. Such control scheme will contribute to prevention of unexpected vehicle body travel by an erroneous operation.
According to still another aspect of the disclosure, the first operational tool comprises a push button that is operated by a finger of the driver; and the second operational tool comprises a pivot lever that is operable by a hand of the driver engaged in operation on the first operational tool. With this arrangement, it becomes possible to cause the vehicle body to travel forwardly or reversely by an easy and distinct one-hand operation of the driver with pivotally operating the pivot lever by the other fingers than the finger used in pushing the first operational tool.
Prior to description of embodiments of a work vehicle relating to the present invention, with reference to
A work vehicle can mount a front implement 7A at a vehicle body front portion and a rear implement 7B at a vehicle body rear portion. In
In the example shown in
The first operational signal outputted from the first operational tool 81 and the second operational signal outputted from the second operational tool 82 are inputted to a signal input section 51 of a traveling control unit 50 and evaluated by a signal evaluating section 52. This signal evaluating section 52 has a function of outputting a traveling command for causing the vehicle body to travel forwardly or reversely based on the first operational signal and the second operational signal.
Incidentally, in this detailed disclosure, in the “forward” traveling and “reverse” traveling under the forward facing posture, the work vehicle moves in directions opposite to the “forward” traveling and “reverse” traveling under the reverse facing posture. In particular, as shown in
In order to output a traveling command for forward or reverse traveling, the signal evaluating section 52 requires, as “prerequisites” therefor, input of the first operational signal (ON signal) indicating the first operational tool 81 being operated, and input of the forward operational signal or reverse operational signal. Namely, for realizing forward traveling or reverse traveling of the vehicle body, the driver needs to operate the first operational tool 81 and the second operational tool 82 with using his/her one hand.
In order to make distinct the intension of forward or reverse traveling of the vehicle body by the driver under the reverse facing posture, it is preferred that input timings (chronological operations) of the first operational signal and the second operational signal be used as another prerequisites for outputting a traveling command for forward traveling or reverse traveling. For this reason, according to a preferred embodiment of the present invention, the signal evaluating section 52 is configured to output a traveling command for causing the vehicle body to travel forwardly or reversely based on input of the second operational signal (forward operational signal or reverse operational signal) under a state of the first operational signal (ON signal) being inputted. That is, in order to cause the vehicle body to travel forwardly or reversely, the driver needs to operate first the first operational tool 81 and then the second operational tool 82 in succession thereto.
As shown in
Similarly, when an ON signal is inputted to the traveling control unit 50 in response to the first operational tool 81 being operated firstly, and thereafter the second operational tool 82 is operated to the reverse traveling side so that a reverse operational signal is inputted to the traveling control unit 50, then a reverse traveling command is outputted, thereby to cause the vehicle body to travel reversely (i.e. travel in the first direction). In this case too, it is preferred that information indicative of traveling preparation completion be notified to the driver through a notifying device such as a buzzer, a light, etc.
Although shown only schematically in
Such vehicle traveling effected under the reverse facing posture is not a “normal” vehicle traveling. So, this traveling is effected generally at a low speed. And, at such low speed, speed change is not so important. From this point view, if the reverse-facing forward traveling speed and the reverse-facing reverse traveling speed realized by the operation on the one-hand control type forward/reverse operational unit 8 are set respectively as a speed which is equal to or lower than a half of the maximum speed that can be realized by this work vehicle and which also is a constant speed, this will be advantageous since this arrangement involves simplification of the control arrangement also. Furthermore, in the case of reverse traveling which is the reverse traveling under the driver's reverse facing posture (vehicle body movement in the first direction), the traveling course visibility is poorer than the forward traveling which is the forward traveling under the driver's reverse facing posture (vehicle movement in the second direction). For this reason, it is advantageous to set the reverse facing reverse traveling speed lower than the reverse facing forward traveling speed. More particularly, it is proposed that the reverse facing forward traveling speed realized by an operation on the one-hand control type forward/reverse operational unit be set as a constant speed which is equal to or lower than a half of a forward maximum speed under the forward facing posture and the reverse facing reverse traveling speed realized by an operation on the one-hand control type forward/reverse operational unit be set as a constant speed which is equal to or lower than a half of a reverse maximum speed under the forward facing posture.
For the sake of greater comfort for the driver's operation under the reverse facing posture, it will be convenient if the driver's seat adapted for the forward facing posture operation is reversible between forward and reverse orientations, so as to allow both the forward facing posture and the reverse facing posture to be realized by the driver seated in the same driver's seat. Moreover, in general, for the forward/reverse operation of the vehicle body under the forward facing posture, a foot pedal is employed. But, it is also important to avoid occurrence of unexpected vehicle body traveling by an erroneous stepping-on operation on the foot pedal by someone other than the driver himself/herself. For this reason, according to one preferred embodiment, there is provided a foot pedal type forward/reverse operational unit (provided generally in the form of a speed changer pedal) operable under the forward facing posture; and the driver's seat is selectable between a forward facing position suitable for an operation of the foot pedal type forward/reverse operational unit and a reverse facing position suitable for an operation of the one-hand control type forward/reverse operational unit; and the travel control unit is configured to disable an operation on the foot pedal type forward/reverse operational unit when the driver's seat is set to the reverse facing position. In view of the current situation that the vehicle body traveling under the reverse facing posture is limited to traveling for a relatively short distance at a relatively low speed, it may also be a preferred option to configure such that when the driver's seat is set to the forward facing position, operations of both the foot pedal type forward/reverse operational unit and the one-hand control type forward/reverse operational unit are enabled, thus improving general versatility thereof.
With reference to
The vehicle body 3 further mounts a stepless speed changer device 40 connected to a rear portion of the engine 4, and a transmission 12 for transmitting an output of the stepless speed changer device 40 to the rear wheels 2 and optionally also to the front wheels 1 when needed. The stepless speed changer device 40 can be a hydrostatic stepless speed changer device (called “HST” for short) or a hydraulic mechanical stepless speed changer (called “HMT” for short). In this particular embodiment, as an HST is employed, so the stepless speed changer device 40 will referred to as the HST 40 hereinafter.
As shown in
In an operational panel 17 disposed laterally of the driver seated at the driver's seat 60 under the reverse facing posture, there is disposed a one-hand control type forward/reverse operational unit 8.
Laterally of the driver's seat 60 at its forward facing position, there is disposed a bucket loader operational tool 62 for operating the bucket loader 7A under the forward facing posture. Rearwardly of the driver's seat 60 at its reverse facing position, there is disposed a backhoe operational tool 63 for operating the backhoe 7B under the verse facing posture.
The first direction proportional control valve 451 and the second direction proportional control valve 452 are operated based on control signals transmitted from a control device 5 via an instrument control unit 94. When the speed changing cylinder 450 is displaced by the first direction proportional control valve 451 and the second direction proportional control valve 452, a swash plate angle of the variable displacement hydraulic pump 43 is varied. In association with this change in the swash plate angle, the engine power inputted to the input shaft 41 is speed-changed steplessly as a forward driving force or a reverse driving force and outputted as such via the output shaft 42. With this, the front wheels 1 and the rear wheels 2 are driven, so that the vehicle body 3 is moved in the first direction (forward traveling in the case of the forward facing posture operation, or reverse traveling in the case of the reverse facing posture operation) or moved in the second direction (reverse traveling in the case of the forward facing posture operation or forward traveling in the case of the reverse facing posture operation).
As shown in
The control device 5 includes an input/output interface 90, a traveling control unit 50, a work control unit 54, a notification control unit 55, and so on. The input/output interface 90 inputs signals from the push button 81 of the one-hand control type forward/reverse operational unit 8, the forward switch 82f, the reverse switch 82r, the rotation detector 93 of the speed changer pedal 31, etc. Further, the interface 90 inputs also signal from a seat detector 91 for detecting the forward facing position or the reverse facing position of the driver's seat 60.
Moreover, to this input/output interface 90, there are connected a notification device 92 constituted of a buzzer, a lamp or the like receiving a control signal from the control device 5, and the instrument control unit 94 that provides a control signal to the first direction proportional control valve 451 and the second direction proportional control valve 452 described hereinbefore.
The traveling control unit 50 has a function of controlling forward traveling and reverse traveling of the vehicle body 3 and implements the basic principle as described above with reference to
The work control unit 54 has such functions as a function of providing a control signal to the bucket loader 7A based on an operational signal generated by an operation on the bucket loader operational tool 62 (see
Next, with reference to the timing chart shown in
An example of forward operation will be described by way of lapse of time from a timing: t1 to a timing: t5. Here, firstly, as the pivot lever 82 is pivotally operated to the forward position (F), the forward operational signal acting as a second operational signal is turned ON (timing: t1). Thereafter, as the push button 81 is pushed, the first operational signal is turned ON (timing: t2). The signal evaluating section 52 is configured to ignore a pivotal operation on the pivot lever 82 unless this pivotal operation on the pivot lever 82 is preceded by a push operation on the push lever 81, so that at this stage, the tractor remains stationary. Then, if the pivot lever 82 is temporarily returned to the neutral position (N), the forward operational signal is turned OFF (timing: t3). Thereafter, when the pivot lever 82 is again pivotally operated to the forward position (F), the forward operational signal is turned ON (timing: t4). As the current ON state of the forward operational signal at this timing: t4 is preceded by the ON state of the first operational signal by a pushing operation on the push button 81, the notification control unit 55 will activate the buzzer acting as the notification device 92 and also the signal evaluating section 52 outputs a traveling start command (forward traveling) (timing: t4). In response to this output of traveling start command (forward traveling), a control signal is outputted to the speed changing control unit 45 and the swash plate angle of the HST 40 is displaced from the neutral position (N) to a forward side predetermined angle: θ1. As this forward side predetermined angle: θ1 is as an angle which is much smaller than a swash plate angle corresponding to the maximum speed, the tractor will make creeping forward traveling. When the tractor has advanced to reach the predetermined position, the driver will remove the finger from the push button 81 to turn this button 81 OFF or remove the fingers from the pivot lever 82 to allow this lever 82 to return to the neutral position (N), the signal evaluating section 52 outputs a traveling stop command (timing: t5). In response to this output of traveling stop command, the buzzer stops sounding and the swash plate angle of the HST 40 is returned to the neutral position (N), whereby the tractor will be stopped.
Incidentally, in case the ON state of the first operational signal by a pushing operation on the push button 81 precedes the ON state of the forward operational signal from the beginning, the signal evaluating section 52 will output the traveling start command (forward traveling) upon turning of the forward operational signal to ON state.
Next, an example of reverse operation will be described by way of lapse of time from a timing: t11 to a timing: t13. In this example, as the push button 81 has been pushed prior to a pivotal operation on the pivot lever 82 thus turning the first operational signal ON (timing: t11), at this timing, the buzzer is activated. In succession, as the pivot lever 82 is pivotally operated to the reverse position (R), the reverse operational signal acting as a second operational signal is turned ON, so that the signal evaluating section 52 outputs a traveling start command (reverse traveling) (timing: t12). In response to this output of traveling start command (reverse traveling), a control signal is outputted to the speed changing control unit 45 and the swash plate angle of the HST 40 is displaced from the neutral position (N) to a reverse side predetermined angle: 02. With this, the tractor will make creeping reverse traveling.
Incidentally, in this embodiment, the predetermined angle: θ2 to the reverse side is set smaller than the predetermined angle:θ1 to the forward side, so that the reverse traveling is made at a speed lower than the forward traveling. When the driver removes the finger from the push button 81 to turn this button 81 OFF or remove the fingers from the pivot lever 82 to allow this lever 82 to return to the neutral position (N), the signal evaluating section 52 outputs a traveling stop command (timing: t13). In response to this output of traveling stop command, the buzzer stops sounding and the swash plate angle of the HST 40 is returned to the neutral position (N), whereby the tractor will be stopped.
(1) In the foregoing embodiment, the first operational tool 81 constituting the one-hand control type forward/reverse operational unit 8 operated by one hand is provided as a push button, and the second operational tool 82 is provided as a pivot lever, and also the first operational tool 81 is disposed in the lateral face of the grip of the second operational tool 82. Instead of this, both the first operational tool 81 and the second operational tool 82 can be provided each as a pivot lever operable by one hand. Further alternatively, the first operational tool 81 and the second operational tool 82 can be combined into a single three-direction operational tool configured to output the first operational signal in response to an operation in a first direction, the forward operational signal in response to an operation in a second direction and the reverse operational signal in response to an operation in a third direction, respectively. Still further alternatively, the second operational tool can be comprised of a forward button and a reverse button, so that the three push buttons together constitute the one-hand control type forward/reverse operational unit 8.
(2) In the foregoing embodiment, forward traveling and reverse traveling provided by the one-hand control type forward operational unit 8 are effected each at its constant speed which is set in advance. Instead, the reverse switch and the forward switch can be comprised each of a detector capable of detecting a variable operational amount, such as a potentiometer, so that speed adjustment may be realized also in the forward traveling and the reverse traveling by the one-hand control type forward/reverse operational unit 8.
(3) An arrangement can be provided such that, in case an operation by the second operational tool 82 is disabled due to e.g. connection failure of the reverse switch and/or the forward switch, forward traveling can be provided by the first operational tool 81 alone.
(4) The work vehicle according to the present invention is applicable to a multi-purpose (utility) work vehicle, in particular, a construction or civil engineering work vehicle, other than the tractor.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2015-142179 | Jul 2015 | JP | national |
