WORKING VEHICLE

Abstract: The present invention is a working vehicle having high visibility and transportability and capable of providing a large excavation force over a wide range. To this end, a working unit (30) is provided with a boom (31) divided into a first boom (31a) and a second boom (31b) and an arm (32) fixed to a front end portion of the second boom (31b). The first boom (31a) is free to swing by a first boom cylinder (36) and the second boom (31b) is free to swing by a second boom cylinder (37). One end portion of a first arm link (33a) is attached to a front end portion of the second boom (31b), and one end portion of a second arm link (33b) is attached to a rear end portion of the arm (32), the other end portion of an arm cylinder (38) and the other end portions of the first arm link (33a) and the second arm link (33b) being connected together.

Description: Technical Field The present invention relates to a working vehicle, and particularly to a working vehicle having a working unit such as a bucket or the like ahead of the operator's seat. Background Art As a working vehicle having a working unit such as a bucket and so on forward of an operator's seat, there is, for example, Japanese Patent Application laid-open No. 6-136779 (& WO-A-94/08098 and also US-A-5 584 643, although the latter published too late) which is previously proposed by the applicant. A construction equipment 100 being one of working vehicles has a first boom 131 a attached to a vehicle body frame 121, a second boom 131 b attached to the first boom 131 a, and an arm 132 attached to the second boom 131 b, so as to be respectively free to swing. To the arm 132, a working unit 130 having a bucket 133 and the like is attached. The bucket 133 in a traveling posture is stably placed on a bracket 115 fixed on the front portion of a base frame 111 and stably housed by hooking the front end portion of the bucket with a hooking device 116. The construction equipment 100 is provided with a first boom cylinder 135 attached to the vehicle body frame 121 and the second boom 131b and swinging the second boom 131b, a second boom cylinder 136 attached to the second boom 131 b and the first boom 131 a and swinging the second boom 131b, and an arm cylinder 137 attached to the second boom 131b and the arm 132 and swinging the arm 132. As for these booms, cylinders, and so on, the vehicle body frame 121 and the fist boom 131a are connected by a pin 123, the first boom 131a and the second boom 131b are connected by a pin 141, the vehicle body frame 121 and the first boom cylinder 135 are connected by a pin 124, and the second boom 131b and the first boom cylinder 135 are connected by a pin 143. In the housing posture illustrated in the drawing, relative to the line connecting the pin 123 and the pin 141, the pin 124 is positioned near one end portion of the line and the pin 143 is positioned near the other end portion of the line. However, in the traveling posture (Fig. 4) with the working unit 130 being housed, the above-described construction equipment 100 has increased front overhang amount 112 and greater rotation radius. For example, when an operator's cab 160 is attached on the left side while the working unit 130 is attached on the right side, a height of housing posture 113 of the arm 132 and the arm cylinder 137 becomes great, therefore there is a disadvantage of low visibility of the lower part on the right side in front. As the art for improving the above-described visibility, a construction equipment 110 illustrated in Fig. 5 is known. The construction equipment 110 has a higher visibility of the side portion in a traveling posture with the working unit 130 being housed as compared to the construction equipment 100 in a housed posture. However, since a height of housing posture 114 of the working unit 130 is high, the position of the center of gravity of the construction equipment 110 becomes high, and a disadvantage exists in the stability at the time of traveling at high speed. Other working vehicles of prior art which also show the disadvantage of low visibility are known from the US-A-4 393 607 and the WO-A-94/08098. According to the US-A-4 393 607, an implement attached boom-arm linkage has a first and a second boom with an arm assembly pivoted end to end. But when the implement is retracted into ist traveling configuration, the second boom is always positioned above the first boom, not housed inside the first boom. And according to the WO-A- 94/08098, upon which the preamble of claim 1 has been based, the working vehicle also consists of a first boom and a second boom and an arm assembly pivoted end to end. But when the unit is in a housed position, the second boom is also positioned above the first boom, not housed inside the first boom. Further, as the number of traveling vehicles on roads is increasing recently, the improvement of the transportability (traveling ability) of working vehicles on ordinary roads is strongly demanded. Especially, for working vehicles which frequently have to go to different working places, the ability of traveling on an ordinary road as well as increased traveling speed at the time of transportation is demanded. In this case, stability at the time of traveling at high speed, cornering ability, reduction of the entire length, visibility, agility, and so on are demanded. Disclosure of the Invention The present invention is made in order to eliminate the above-described disadvantages in the conventional art, and it is an object of the invention to simplify operation when driving the working vehicle with its jib retracted into the traveling position. According to the invention a working vehicle is provided having high visibility and transportability, and a large excavating force over a wide range, with a working unit smoothly operated. The working vehicle relating to the present invention is a working vehicle comprising an upper rotary body rotatably supported on a base carrier so as to support a working unit and an operator's cab located thereupon, said working unit including a boom, an arm and a bucket; wherein the boom of said working unit is divided into a first boom, pivotally mounted at its proximal end on said upper rotary body, and a second boom pivotally linked at its proximal end to a distal end of said first boom; wherein a proximal end of the arm is pivotally linked to a distal end of said second boom, the bucket being supported for pivotal movement at the distal end of said arm; wherein a first boom cylinder has one end portion attached to said upper rotary body, the other end portion thereof being attached to said second boom proximate the pivotal link between said first and said second boom and on the distal side thereof, and wherein a second boom cylinder has one end portion attached to the rear end portion of said second boom, the other end portion thereof being attached to an intermediate portion of said first boom; whereby said first and second cylinders cooperate under power actuation to coordinate pivoting of both the first and the second booms characterized in that said first boom is adapted to receive said second boom substantially inside a second boom housing cavity formed therein, whereby said second boom is received substantially inside said second boom housing cavity at least whenever said boom is in its retracted travelling condition. Further, it is desirable that the arm cylinder has one end portion attached to said second boom jointly with the other end portion of the first boom cylinder, a first arm link has one end portion attached to a front end portion of said second boom, and that a second arm link has one end portion attached to a rear end portion of said arm , and each of the other ends of said arm cylinder, said first arm link and said second arm link are connected together; wherein said arm is parallel to a top surface of a base frame of said base carrier in condition in which said arm cylinder is retracted; and wherein the posture of said working unit at the time of traveling is a housed posture in which said devided boom in a housed condition and the arm with said arm cylinder in a retracted condition substantially make a V-shaped form. According to the above-described configuration, in which the divided boom is used, the second boom is rotated with the second pin as its fulcrum by contracting the rod of the second boom cylinder at the time of the operation from the hosing posture to the working posture. By extending the first boom cylinder simultaneously with this contraction, the first boom is rotated in a counterclockwise direction with the first pin as its fulcrum. In the housing posture, when the line connecting the centers of the first and second pins is a reference, the line connecting the centers of the first and the sixth pins has an angle in a counterclockwise direction, therefore a derricking operation is carried out smoothly. When the working unit is shifted from the housing posture to the working posture, or from the working posture to the housing posture, the divided boom is smoothly operated over extremely wide range by supplying an actuator oil to the second boom cylinder and the first boom cylinder. When the first and the second arm links are operated by derricking the arm cylinder, the rotation angle of the arm greater than the conventional art can be obtained relative to the stroke of the arm cylinder since the length between the centers of the ninth and tenth pins are made relatively greater. In addition, since the radius of the rotation moment is greater than the conventional art, the excavating force at the edge of front end of the bucket is increased. Further with the second boom housing section is provided inside the first boom, the divided boom is in a compact housed posture since the second boom is housed by extending the second boom cylinder. Accordingly, since an operator in an operator's cab can obtain excellent visibility with the housing posture at the time of traveling, safety can be secured. Further, the arm at the time of being housed becomes almost parallel to the top surface of the base frame, and the arm and the divided boom are made to be substantially in a V-shaped form. Thereby, excellent visibility can be obtained, while the center of gravity of the working unit is at a lower position, so that stability can be secured at the time of traveling at high speed. Brief Description of the Drawings Fig. 1 is a side view of a working vehicle in a housing posture relating to an embodiment of the present invention; Fig. 2 is a side view of a working vehicle in a working condition relating to the embodiment; Fig. 3 is a view seen from the direction of an arrow III in Fig. 2 and explaining the configuration in which a second boom and a second boom cylinder are housed in a first boom; Fig. 4 is a side view of a working unit of the working vehicle relating to the conventional art; and Fig. 5 is a side view of the working unit in a traveling and transporting posture relating to the working vehicle of another conventional art. Best Mode for Carrying out the Invention A preferable embodiment of a working vehicle relating to the present invention will be particularly described with reference to the attached drawings. In Fig. 1 and 2, a working vehicle 1 includes a base carrier 10 and an upper rotary body 20 placed on the base carrier 10 so as to be free to rotate with the point close to a center of the base carrier 10 as its center of rotation CL. The working vehicle 1 also includes a working unit 30 which is placed on a vehicle body frame 21 on the upper rotary body 20 and which is free to derrick relative to the upper rotary body 20, and an operator's cab 60 for an operator 61 to sit in to operate the working unit 30. The base carrier 10 includes wheels 12 which are rotated by an oil hydraulic motor for running (not illustrated) equipped on a base frame 11 or the like and which run the working vehicle 1, and a rotation bearing 13 supporting the upper rotary body 20 positioned on the base frame 11. Incidentally, the wheels 12 can be an endless crawler belt. The upper rotary body 20 consists of the vehicle body frame 21 supported by the rotation bearing 13, and a rotary body cover 22 attached to the vehicle body frame 21 and including a counter weight 22a. The upper rotary body 20 is installed so as to be free to rotate in a horizontal direction relative to the center of rotation CL located almost at the center of the base frame 11 both in a width direction and in a fore-and-aft direction, and the upper rotary body 20 is rotated by an oil hydraulic motor for rotation (not illustrated) actuated by the operation of the operator 61 in the operator's cab 60. A first pin 23 supporting the working unit 30 so as to be free to derrick is attached to the vehicle body frame 21. A fifth pin 24 attached to the vehicle body frame 21 supports one end portion of a first boom cylinder 36 and by the extension and contraction of the first boom cylinder 36, a second boom 31b is operated so as to be free to derrick. The first pin 23 and the fifth pin 24 are fixed pins attached to the vehicle frame 21. Further, the oil hydraulic motor for rotating the working vehicle 1, a change-over valve (not illustrated) of each of the above-described cylinder for derricking the working unit 30, and so on are positioned inside the rotary body cover 22. The working unit 30 includes a boom 31 consisting of a first boom 31a and the second boom 31b as well as being capable of bending, an arm 32, a bucket 34, the first boom cylinder 36, a second boom cylinder 37, an arm cylinder 38, and a bucket cylinder 39. The working unit 30 also includes a first and a second arm links 33a and 33b connected to the arm 32 and the second boom 31b, bucket links 35a and 35b connected to the arm 32 and bucket 34, and a number of pins described below connecting each member, oil hydraulic cylinders and so on. The above-described pins are configured in such a way as to include a connecting pin fixed at the first boom 31a and a bush to be inserted into the hole of the second boom 31b, for example, in the case of a second pin 41 connecting the first boom 31 a and the second boom 31b as well as supporting the second boom 31b. Or, the pins are configured in a reverse way, specifically, by including the connecting pin fixed at the second boom 31b and the bush inserted into the hole provided on the first boom 31a. A preferable configuration is the one in which a connecting portion of one member has a crotch and in which a connecting portion of the other member is inserted into the crotch and linked by a pin, but other ordinary configurations of the connecting portions are suitable, without being limited to the above-described configuration. The first boom 31a is attached at the vehicle body frame 21 through the first pin 23 so as to be free to swing, and has the second pin 41 supporting the second boom 31b and a third pin 42 supporting the second boom cylinder 37. The detailed form of the first boom 31a will be explained with reference to Fig. 3. The first boom 31 a has side panels 31 L and 31 R defined by box-shaped members connected and fastened by a connector 31C. Both end portions of the side panels 31L and 31R have a forked connecting portion fulcrum 23a to be connected to the first pin 23 and a forked connecting portion fulcrum 41 a to be connected to the second pin 41. A forked connecting portion fulcrum 42a provided on the first pin 23 side of the connector 31C holds the bottom side of the second boom cylinder 37 through the third pin 42 and allows the bottom side thereof to be free to rotate. On the other hand, the rod side of the second boom cylinder 37 is connected to a forked connecting portion fulcrum 44a of the second boom 31b through a fourth pin 44 so as to be free to rotate. The forked connecting portion fulcrum 41a holds one end of the second boom 31b through the second pin 41 and allows the second boom 31b to be free to swing. In the above-described configuration in Fig. 3, by extending the rod of the second boom cylinder 37, the second boom 31b rotates with the second pin 41 as the axis of rotation, and is inserted between the side panels 31L and 31R of the first boom 31a to be housed in a second boom housing section 31d in such a way as to face the second boom cylinder 37. Returning to Fig. 1, the second boom 31b is provided at one end portion with a sixth pin 43 attaching the first boom cylinder 36 connecting to the vehicle frame 21 and the arm cylinder 38. Also at the one end portion, the second boom 31b is provided with the fourth pin 44 attaching the second boom cylinder 37 connecting to the first boom 31 a. On the other hand, on the other end portion, the second boom 31b is provided with a seventh pin 45 supporting the arm 32 and a tenth pin 47 supporting the first arm link 33a. The second boom 31b is provided with forked fulcrums 43a and 44a so as to insert and hold the rod portion of the second boom cylinder 37 and the bottom portion of the arm cylinder 38 therein. Thereby, the arm cylinder 38 can be housed in the second boom 31b with the rod being contracted. The arm 32 is attached at the second boom 31b through the seventh pin 45 so as to be free to swing. At the end portion of the arm 32 adjacent to the seventh pin 45, an eighth pin 48 attaching the second arm link 33b and a pin 49 attaching the bucket cylinder 39 are provided. At the front end portion of the arm 32, a bucket supporting pin 51 allowing the bucket 34 to be free to swing and a bucket link supporting pin 52 supporting the bucket link 35a are attached. The bucket 34 is connected to the bucket link 35b through the bucket link supporting pin 53. 34a shows the front end of the bucket. Bucket link 35a is attached to the arm 32 through the bucket link supporting pin 52 so as to be free to swing, and is connected to the bucket link 35b through a pin 50. To the pin 50, the arm cylinder 39 is also connected. The first boom cylinder is defined by two pieces in such a way as to hold the second boom 31b between. In the two pieces of the first boom cylinders 36, each bottom portion is attached at the fifth pin 24 of the vehicle body frame 21, and each rod portion is attached at the sixth pin 43 of the second boom 31b. The second boom cylinder 37 has the bottom portion attached at the third pin 42 of the first boom 31 a, and the rod portion attached at the fourth pin 44 of the second boom 31 b. As for the arm cylinder, the bottom portion is attached at the sixth pin 43 of the second boom 31b, and the rod portion is attached at the arm links 33a and 33b through the ninth pin 46. The bucket cylinder 39 has the bottom portion attached at the pin 49 of the arm 32, and the rod portion attached at the bucket links 35a and 35b. The attachment of each cylinder in the embodiment can be conducted by reversing the bottom portion and the rod portion as necessary. The operation by the above-described configuration will be explained. As for a line connecting two centers of pins, for example, the line connecting the center of the first pin 23 and the center of the second pin 41 is expressed as a line segment 23 / 24. In Fig. 1 which shows a housing posture of the working unit 30, when the first pin 23 is the center of the base end portion of the hands of a clock, the first boom 31 a is at the position of two o'clock, and the first boom 31a is parallel to the second boom 31b. Then, when the center of the first pin 23 is a reference point with the line segment 23 / 41 is a reference line, and when an angle in a counterclockwise direction is a positive number, and an angle in a clockwise direction is a negative number, an angle A made by the line segment 23 / 41 and a line segment 23 / 43 is a positive number. Accordingly, when derricking the working unit 30 from the housing posture, a smooth derricking operation can be attained. In the housing position with the arm cylinder 38 being contracted at the time of transport, the second boom 31b is housed in the inside of the first boom 31a with the second pin 41 as the fulcrum. At the same time, the arm cylinder 38 is housed in the inside of the second boom 31b with the sixth pin 43 as the fulcrum. Accordingly, the second boom 31 b and the arm cylinder 38 are compactly housed. In this position, the bottom surface of the arm 32 is almost parallel to the top surface 11 a of the base frame 11. By placing the arm 32 directly on the top surface 11 a, or on the stabilizing member equipped on the top surface 11a, the working unit 30 is stabilized at the time of traveling. In addition, since the center of gravity of the working unit 30 is at a low position, excellent stability can be obtained. Further, by removing a conventional hooking device 116 (Fig. 4, Fig. 5), front overhang amount is decreased, so that excellent agility and cornering ability at a small working site can be obtained. Incidentally, in the housing posture, the first and second booms 31a and 31b and the arm 32 are almost in a V-shaped form. In an excavating condition in Fig. 2, when the arm cylinder 38 is extended, the first arm link 33a is rotated in a counterclockwise direction with the tenth pin 47 as its fulcrum. Since the first arm link 33a is connected to the arm 32 through the second arm link 33b, the arm 32 is rotated in a counterclockwise direction with the seventh pin 45 as its fulcrum. At the time of this rotation, the length of a line segment 46 / 47 (specifically, the distance between the pins of the first arm link 33a) is greater than a line segment 45 / 48. On the other hand, in the conventional art, when explaining by using Fig. 2 of the present embodiment, the arm cylinder 38 is directly connected to the eighth pin 48 without attaching the first and the second arm links 33a and 33b. Accordingly, by attaching the first arm link 33a having the relatively great distance between the pins, the angle of rotation of the arm 32 is increased even with the stroke of the arm cylinder 38 same as the conventional art. Since a radius of rotation moment M2 of the present embodiment is greater than the conventional M1, an excavating force F at the cutting edge of the bucket front end 34a is great and is obtained over a wide range of the angle of rotation of the arm 32. Next, the visibility will be explained with reference to Fig. 1. As for the placement, the working unit 30 equipped with the bucket 32 and so on is attached on the right portion of the rotary vehicle body frame 21, and the operator's cab 60 is attached on the left portion of the vehicle body frame 21. On both side walls of the operator's cab, a lower side window 63, an upper side window 64, and a rear side window 65 are provided. Inside the operator's cab 60, an operation lever (not illustrated) for an actuating operation of the working unit 30 is housed. When the working unit 30 is in a housing posture, the position of the seventh pin 45 connecting the second boom 31b to the arm 32 is on the vehicle body frame 21 and is lower than a line connecting an eye point 62 of the operator 61 and a front fender nose 21 a of the vehicle body frame 21. Thereby, the operator 61 can see the right side of the working vehicle 1 which is in the working unit 30 side, and the front lower part of the front fender nose 21a on the right side, and therefore the visibility is improved. Incidentally, in Figs. 1 and 2, the operator's cab is provided before the working unit 30, and is illustrated by a phantom line in order to make the configuration of the working unit 30 understandable, which is on the side of the shade of the operator's cab 60. Industrial Availability The present invention is useful as a working vehicle having a great excavating force over a wide range with smooth operation of the working unit, whereby a visibility is excellent when the working unit is housed therein and an excellent transportability can be obtained.

Claims: A working vehicle comprising an upper rotary body rotatably supported on a base carrier so as to support a working unit and an operator's cab located thereupon, said working unit including a boom, an arm and a bucket; wherein the boom (31) of said working unit (30) is divided into a first boom (31a), pivotally mounted at its proximal end on said upper rotary body, and a second boom (31 b), pivotally linked at its proximal end to a distal end of said first boom; wherein a proximal end of the arm (32) is pivotally linked to a distal end of said second boom (31 b), the bucket (34) being supported for pivotal movement at the distal end of said arm (32); wherein a first boom cylinder (36) has one end portion attached to said upper rotary body, the other end portion thereof being attached to said second boom (31b) proximate the pivotal link between said first and said second boom (31a, 31b) and in the distal side thereof; and wherein a second boom cylinder (37) has one end portion attached to the rear end portion of said second boom, the other end portion thereof being attached to an intermediate portion of said first boom (31a); whereby said first and second cylinders (36, 37) cooperate under power actuation to coordinate pivoting of both the first and the second booms (31a, 31b); characterized in that said first boom (31 a) is adapted to receive said second boom (31b) substantially inside a second boom housing cavity (31d) formed therein, whereby said second boom (31b) is received substantially inside said second boom housing cavity (31d) at least whenever said boom (31) is in its retracted travelling condition. Working vehicle according to claim 1; wherein an arm cylinder (38) having one end portion ) attached to said second boom (31b) jointly with the other end portion of the first boom cylinder (36), a first arm link (33a) having one end portion attached to a front end portion of said second boom (31 b), a second arm link (33b) having one end portion attached to a rear end portion of said arm (32), and each of the other ends of said arm cylinder (38), said first arm link (33a), and said second arm link (33b) being connected together; wherein said arm (32) is parallel to a top surface (11a) of a base frame (11) of said base carrier (10) in condition in which said arm cylinder (38) is retracted; and wherein the posture of said working unit (30) at the time of traveling is a housed posture in which said divided boom (31) in a housed condition and the arm (32) with said arm cylinder (38) in a retracted condition substantially make a V-shaped form.

Inventors: OHBATAKE YOUJIROU, SASAKI HIDETOSHI, OHBATAKE, YOUJIROU, SASAKI, HIDETOSHI, OHBATAKE, Youjirou Komatsu Awazu Plant 23, Tsu
Applicants: KOMATSU MFG CO LTD, KOMATSU LTD.
Application year: 1995
Main classification: E02F3
IPC codes: E02F3, E02F9