Loader work machine

The invention provides a loader work machine with improved front visibility and improved aesthetic appearance. The loader work machine includes a self-propelled machine body, a work device having a boom, a boom cylinder, and a side frame for vertically pivotally supporting base portions of the boom and the boom cylinder, and a frame unit for attaching the work device to the self-propelled machine body. The frame unit has a support platform projecting laterally outward from the self-propelled machine body and a main frame mounted erect on the support platform for supporting and connecting a lower portion of the side frame. An accumulator is connected to the boom cylinder for absorbing shock occurring during a vertical pivotal movement of the work device and this accumulator is attached to the frame unit.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a loader work machine. The term “loader work machine” as used herein refers generically to a group of loading/unloading vehicles for use in agricultural works, civil engineering works, etc. some non-limiting examples of which include a tractor mount type loader formed by mounting a front loader and/or a backhoe to a tractor, a self-propelled loader (wheeled loader, self-propelled backhoe, a power shovel, etc.)

2. Description of the Related Art

There is known a loader work machine in which an accumulator for absorbing shock occurring during a vertical pivotal movement of a work device (e.g. a front loader) connected to a self-propelled vehicle body is connected to a hydraulic circuit (see e.g. Japanese Utility Model Application “Kokai” No. 56-171868). This accumulator is disposed adjacent a boom cylinder forwardly, rearwardly or upwardly, etc. of a connecting pipe interconnecting right and left boom members.

However, when the work device is connected to the self-propelling vehicle body, the accumulator is attached to a relative high position of the loader work machine. Hence, due to this accumulator, the front visibility from a driver's seat is deteriorated. Moreover, the attachment of the accumulator to the connecting pipe deteriorates not only the front visibility, but the aesthetic appearance.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a loader work machine which overcomes the above-described drawback.

For accomplishing the above-noted object, a loader work machine, according to the present invention, comprises:

a self-propelled machine body;

a work device having a boom, a boom cylinder, and a side frame for vertically pivotally supporting base portions of the boom and the boom cylinder;

a frame unit for attaching the work device to the self-propelled machine body, the frame unit including:a support platform projecting laterally outward from the self-propelled machine body, anda main frame mounted erect on the support platform for supporting and connecting a lower portion of the side frame; and

an accumulator connected to the boom cylinder for absorbing shock occurring during a vertical pivotal movement of the work device;

wherein said accumulator is attached to said frame unit.

With the above-described construction, the accumulator is attached to a lower position than the conventional construction. Hence, with elimination of blocking of the front view from the driver's seat toward the work device (e.g. a front loader), the front visibility can be improved and the aesthetic appearance of the work machine can be improved as well.

According to one preferred embodiment, said accumulator is stored within a lower portion of said frame unit. For instance, this accumulator can be stored inside the support platform which is formed like a cylinder.

According to one preferred embodiment, said main frame includes a selector valve operable to switch over the accumulator between a use condition and a non-use condition, with the selector valve being operable from a driver's seat mounted on the self-propelled machine body. With this construction, it is possible to shorten a hydraulic piping between the accumulator and the selector valve. Further, the switchover operation of the selector valve becomes more convenient.

According to one preferred embodiment, said support platform is formed like a cylindrical platform structure which accommodates therein a selector valve operable to switch over the accumulator between a use condition and a non-use condition. With this construction, not only the accumulator, but also the selector valve is accommodated within the support platform. Therefore, the blocking of the front view for the driver can be further prevented and the aesthetic appearance of the machine can be further improved.

Further and other features and advantages of the invention will become apparent upon reading the following detailed description of the preferred embodiments thereof with reference to the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Next, with reference to the accompanying drawings, respective preferred embodiments of the present invention will be described in details based on a tractor mount type loader as an example of a loader work machine relating to the present invention.

First Embodiment

InFIG. 1, there is shown at1a tractor mount type loader comprising a tractor (loading/unloading vehicle)2as a self-propelled machine body and a front loader3as a work device attached to a front portion of the tractor2.

The tractor2includes a pair of right and left front wheels4, a pair of right and left rear wheels5, and a hood6mounted at a front portion of the tractor for covering an engine, a radiator, etc.

The front loader3includes, as principal components thereof, attaching frames7, boom members8and an implement9such as a bucket. The attaching frame7includes a cylindrical support platform10, a main frame11, and a side frame12. And, the pairs of these components are disposed on the right and left sides of the tractor2, respectively.

As shown inFIGS. 1-4, the tractor2includes a front axle frame2A, a flywheel housing2B and a connecting frame2C interconnecting the frames2A,2B along the fore and aft direction.

The connecting frame2C comprises a pair of plate-like members having front half portions thereof fastened to the right and left side faces of the front axle flame2A by a plurality of bolts and having rear half portions thereof fastened to the right and left side faces of the flywheel housing2B by a plurality of bolts. To the front portion of the flywheel housing2B, the engine (not shown) is connected and to the rear portion thereof, a clutch housing, a transmission case and a rear wheel differential device are connected in the mentioned order.

The cylindrical support platform10comprises a metal pipe member such as a cylindrical steel pipe. This support platform10has its right/left inner end inserted into a circular hole2D formed at a rear portion of the connecting frame2C and fixedly welded about this circular hole2D. With this, right/left outer ends of the support platform10project outward in the right/left direction from the tractor2. And, on the right and left outer ends of the support platform10, the main frames1are attached to project upward therefrom. To this end, each main frame11forms, at a lower end thereof, a circular hole11A, in which the right/left outer end of the support platform10is inserted and the support platform10is fixedly welded around this circular hole11A.

Referring more particular to the main frame11, as shown inFIG. 2, at an upper portion thereof, there is integrally formed a cylindrical boss portion11B forming a pin hole having a right/left axis and, at a front portion of a vertically intermediate portion thereof, there is integrally formed a receiving portion11C having an upwardly open arcuate receiving recess. This main frame11is integrally formed as a single plate (thick plate) made of cast steel. In the opposed lateral plate face portions (or one lateral plate face portion), there are formed a plurality of reinforcing ribs11D arranged to intersect with each other in the vertical and fore-and-aft directions, with forming recesses11E between adjacent reinforcing ribs11D for achieving weight reduction.

The main frames11described above are attached to the front opposed lateral faces of the tractor2via the support platforms10and the connecting frames2C so as to detachably connect the side frames12of the front loader3to the front portion of the tractor2.

The side frames12are attached to rear ends of the pair of right and left boom members8of the front loader3so as to detachably connect the front loader3to the front portion of the tractor2with using the main frames11.

To the above end, to the lower end of each side frame12, there is integrally fixed an engaging pin13engageable with the receiving portion11C of the main frame11. Further, at a rear portion of a vertically intermediate portion of the side frame12, there is integrally provided a cylindrical boss portion12A having a pin hole corresponding to the boss portion11B of the main frame11.

Then, with engaging the receiving portions11C of the main frames11to the engaging pins13of the side frames12, the opposed boss portions11B,12A will be placed in registry with each other and the connecting pins14will be inserted therethrough, whereby the front loader3can be connected to the tractor2. Further, by removing the connecting pins14, the front loader3becomes detachable from the tractor2.

The boom member8, as shown inFIG. 1, is bent at a longitudinally intermediate portion thereof, so that this entire member3presents a mountain-like shape convexed upward. Further, the boom member8has a progressively larger height from the fore and rear end portions thereof toward the longitudinally center portion thereof. And, this entire boom member8is formed like a substantially angular tubular structure made of a metal plate member such as a steel plate. And, the pair of the boom members8are provided on the right and left sides of the hood6. The front portions of the right and left boom members8are interconnected via a connecting pipe15.

Each of the right and left boom members8is pivotally connected, at a proximal end (rear end) end thereof, via a pin16to the upper portion of the corresponding side frame12to be vertically pivotal about a right/left axis.

Further, from the longitudinal intermediate portion of each right/left boom member8to a vertically intermediate portion of each right/left side frame12, there is disposed a boom cylinder17comprised of a double acting type hydraulic cylinder. In operation, in association with extension/contraction of these right and left boom cylinders17, the right and left boom members8can be vertically pivoted.

To a rear side lower portion of the implement9, leading ends (front ends) of the respective boom members8are pivotally connected via pins18. And, between the rear face of the implement9and the vicinity of the leading end of each right/left boom member8, opposed ends of a two-foldable extension/contraction link19are connected via pins20,21. Further, between an upper face of the longitudinally intermediate portion of each right/left boom member8and a mid connecting point of the two-foldable extension/contraction link19, there is disposed a bucket cylinder22comprised of a double acting type hydraulic cylinder. Then, in association with extension/contraction of the bucket cylinders22, the implement9can be pivoted (for a rollback or dumping operation).

Along the lower face on the leading end side of the boom member8, a stand23is attached. This stand23is used for supporting the boom member8to allow this member8to stand alone with the implement9being placed on the ground surface, when the front loader3is to be detached from the tractor2. Incidentally, this stand23can be stored and held along the lower face of the leading end side of the boom member8.

To the hydraulic circuit of the boom cylinder17, there is connected an accumulator24. This accumulator24is disposed on the side of the main frame11. In the present embodiment, there is disclosed an exemplary construction wherein the accumulator24is stored within the support platform10of the main frame11. As the support platforms10are provided on the right and left sides of the tractor2, the accumulators24are accommodated similarly within the right and left support platforms10. In the present embodiment, one accumulator24is connected respectively to a boom elevating side oil passage and a boom lowering side oil passage of the hydraulic circuitry (not shown) of the boom cylinder17.

The accumulator24, as shown inFIG. 5, consists essentially of a cylindrical body24A having a slightly smaller outer diameter than the inner diameter of the cylindrical support platform10and a lid member24B air-tightly fastened to the body24A. And, this accumulator24is accommodated within the support platform10via a cushion member25such as a rubber sheet, and an attaching bolt26provided at an end of the body24A is inserted through an attaching plate27affixed to right/left inner side of the cylindrical platform10and fastened thereto by a nut28.

As shown also inFIG. 5, each accumulator24accommodated within the right/left support platform10includes a pipe connecting member29at an end on the right/left outer side of the cylindrical support platform10, and to this pipe connecting member29, a hydraulic pipe31is connected. This hydraulic pipe31is drawn out through an open end on the right/left outer side of the support platform10, and then connected to a selector valve30attached to a side face of the main frame11, which side face is exemplified as a position operable for switchover operation from a driver's set2F of the tractor2. The selector valve30is connected via the hydraulic pipe31to a predetermined connecting port of a control valve32. This control valve32, as shown inFIGS. 2-4, is attached to the right side face of the clutch housing2E constituting a part of the vehicle body of the tractor2. To the selector valve32, there is pivotally attached a handle shaft33. Then, as this handle shaft33is pivoted with a convenient tool (not shown) such as a spanner, the selector valve30switches over the oil passage to an open condition or to a closed condition. With this, the accumulator24is switched over between a use condition and a non-use condition. The above-described operational tool can be permanently attached to the handle shaft33or detachably attached thereto.

In the foregoing embodiment, the selector valve30is provided at the side face of the main frame11as an example of a position switchably operable from the driver's seat2F of the tractor2. Instead, the valve30can be provided at any other position, e.g. to the rear face of the main frame11or can be attached directly or indirectly via an appropriate attaching bracket to a portion of the vehicle body of the tractor2. In short, this selector valve30should be connected to a mid portion of the hydraulic pipe31connecting the accumulator24and the control valve32, and be disposed at a position conveniently operable for switchover from the driver's seat2F of the tractor2.

Incidentally, the selector valve30may be disposed adjacent the accumulator24. For instance, as shown inFIG. 6, the selector valve30may be accommodated within the support platform10together with the accumulator24. In this case, the pivoting operation of the handle shaft33is to be effected by inserting the tool from the open end on the right/left outer side of the support platform10. Incidentally, at this open end on the right/left outer side of the support platform10, there is detachably attached a lid member34made of rubber or plastics for preventing intrusion of dust or the like. This lid member34will be detached when the pivoting operation of the handle shaft33is to be effected.

To the inner face of the main frame11disposed on the right side of the tractor2, there is attached, via a support bracket35, a hydraulic pipe connecting terminal tool36. This hydraulic pipe connecting terminal tool36is connected via a hydraulic pipe37to the control valve32. The control valve32is connected to a hydraulic pump and an oil tank (not shown) mounted on the tractor2. The hydraulic pipe connecting terminal tool36is used for feeding/discharging working oil to/from the boom cylinders17and the bucket cylinders22of the front loader3. The hydraulic pipe (not shown) to the boom cylinders17and the hydraulic pipe (not shown) to the bucket cylinders22are arranged along the boom members8of the front loader3. And, to terminal ends of these hydraulic pipes too, there are provided hydraulic pipe connecting terminal tools (not shown) which are connectable to and detachable from the terminal tool36in the male-female arrangement. These terminal tools will be connected or detached when the front load3is mounted to or dismounted from the tractor2.

Next, the operations of this embodiment having the above-described construction will be described.

As shown inFIG. 1, when a work is to be effected by the front loader3with this loader3being mounted to the tractor2, by selective operations of the selector valves30, there are three types of operations selectable, i.e. one rendering both of the right and left accumulators24usable, another rendering both unusable and still another rendering one of them usable, rendering the other unusable.

First, the case of rendering both of the right and left accumulators24usable is a case where, during a work with vertically pivoting the boom members8by the boom cylinders17, sudden change in the loads due to some cause is expected or it is necessary to avoid generation of such shock per se. In such case, the work will be carried out with opening the right and left selector valves30. With this, even if there occurs sudden surge in the oil pressure in the hydraulic pipes connected to the boom cylinders17, this can be absorbed and relieved by the accumulators24, thus effectively preventing transmission of significant shock to the driver and to the implement9such as the bucket. As a result, it is possible to avoid fall of the load as well as damage to the boom members8and the implement9. Moreover, it is possible to avoid burst of the hydraulic pipes or oil leaks therefrom.

The case of rendering both the right and left accumulators24unusable is a case where the boom cylinders17need to be operated with maximum hydraulic forces. In such case, the work will be effected with closing the right and left selector valves30.

Further, in the case of effecting work with rendering only the elevating operation side accumulator24for the boom cylinder17usable and rendering the lowering operation side accumulator24unusable or in the converse case, the work will be effected with the corresponding one of the right and left selector valves30open and the other closed.

According to the present invention described above, as the accumulator24is accommodated within the support platform10, during a work of the front loader3, the accumulator24does not impair the front view of the driver and the aesthetic appearance is improved also. Further, there is no increase in the weight of the boom members8. Incidentally, the accumulator24need not be accommodated within the support platform10, but may be provided on the side of the main frame11outside the support platform10, and in such case too, no deterioration in the driver's front view will occur and no weight increase in the boom member8will occur, either.

Second Embodiment

FIG. 6shows a loader work machine according to a second embodiment of the present invention.

In this embodiment, the selector valve30is accommodated within the support platform10. With this accommodation within the support platform10, piping layout can be facilitated and the appearance can be improved.

The rest of the construction is identical to the first embodiment.

Other Embodiments

The present invention is not limited to the foregoing embodiments.

For instance, both of the right and left accumulators24can be used only for either elevating or lowering operation of the boom cylinders17. Or, instead of providing the accumulators on the opposed right and left sides, one integral accumulator may be provided to be used for only either elevating or lowering side of the boom cylinders17. In this case, the accumulator24may be accommodated within only one of the right and left support platforms10or may be disposed outside the support platform10to be attached to a portion of the main frame11or a portion of the vehicle body of the tractor2.

Further, the disposing position of the selector valve30is not limited to the one described in the foregoing embodiment. The selector valve30may be disposed outside the support platform10at any appropriate position operable for switchover from the driver's seat2F. For instance, this selector valve30may be attached to a portion of the main frame11, so that the driver as being seated at the driver's seat2F can operate the valve without having to get off the vehicle body.

Incidentally, in the above case of disposing the selector valve30outside the support platform10to be attached to a portion of the main frame11or of the vehicle body, the two selector valves may both be disposed on one either side. This arrangement allows operation of the two selector valves on one side, thus further improving the operability.