JPH0717357B2 - forklift - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a forklift used for cargo handling work such as transportation and lifting of heavy objects.

[Prior Art] Conventionally, a forklift of this type has a side shift mechanism for adjusting the left and right positions of both forks by moving the forks in the same left and right direction as a mechanism for moving the two forks and a left and right fork. And a fork shift mechanism for adjusting the distance between the two forks by moving the forks in the opposite direction.

The drive source and the actuator for moving the fork are covered by the fluid pressure source and the fluid pressure cylinder, which are common to each of the above-mentioned mechanisms, generally a hydraulic pump and a hydraulic cylinder.

[Problems to be Solved by the Invention] However, the conventional forklift has the following problems.

Generally, side shifts of both forks are often carried out with heavy objects placed on the forks during cargo handling work. Therefore, the hydraulic pump to be used has a high pressure such as high pressure oil feed and large amount oil feed to perform various cargo handling work. Pumping capacity is required.

On the other hand, the fork shift of both forks is carried out for the purpose of adjusting the width of the forks before placing the heavy object on the forks.

In other words, the fork shift only moves the fork when no heavy object is placed,
It is performed on the basis of high-pressure oil pumped from a hydraulic pump having a high pumping capacity. For this reason, the moving speed of the fork during the fork shift is inevitably high, and it becomes difficult to finely adjust the fork interval. Further, the hydraulic pump needs to be driven in spite of a light load when no heavy object is placed, and an unnecessary load is applied to the engine that is the drive source of the rotation.

Further, the frame to which the fork or the like is attached needs to have strength because it moves up and down along with the bracket along the mast with a heavy object placed thereon, and is generally composed of a plate body to block the front view of the driver.

The present invention has been made to solve the above problems, and an object of the present invention is to improve the usability at the time of performing a side shift of a fork and a fork shift, and to secure a front view of a driver.

[Means for Solving the Problems] In order to achieve such an object, in the forklift according to claim 1, a frame is attached to a bracket that moves up and down along a mast, and a guide member installed on the frame is moved in the left-right direction. Two freely movable forks are attached, and two fluid pressure cylinders for moving the two forks in the left and right directions are provided on the frame, and fluid is pressure-fed to the two fluid pressure cylinders so that the two cylinders are connected to each other. Between the driven fluid pressure source and the two fluid pressure cylinders, the first fluid of the fluid serves as a flow path for moving the two forks in the same left and right direction by the fluid pressure-fed from the fluid pressure source. A path is provided between the fluid pressure supply source and the two fluid pressure cylinders, and
In a forklift provided with a second path for the fluid, which serves as a flow path for moving the fork of the book in the left-right direction, a main fluid pump having a fluid pressure-feeding capacity which is sufficient for loading and unloading heavy goods. A sub-fluid pump having a fluid pumping capacity sufficient to move the two forks alone, the main fluid pump being connected to the first path,
The sub-fluid pump was connected to the above-mentioned route.

In the forklift according to claim 2, the frame of the forklift according to claim 1 having the above-described structure is formed in a ladder shape in which a supporting frame is provided with vertical ribs.

[Operation] In the forklift according to claim 1 having the above configuration, when the two forks that are movable in the left-right direction with respect to the bracket are moved in the same direction in the left-right direction, the fluid discharged from the main fluid pump is moved to the first path. To each fluid pressure cylinder. In this way, the main fluid pump having a high fluid pressure feeding capability covers the side shift that is often performed while the heavy object is placed on the fork during the cargo handling work.

On the other hand, when moving the two forks in the left and right directions, the fluid discharged from the sub-fluid pump is pumped to each fluid pressure cylinder via the second path. As a result, the fork shift, which merely moves the fork in a state where no heavy object is placed, is covered by the sub-fluid pump having a low fluid pressure feeding capability.

Further, in the forklift according to the second aspect, the frame located in front of the driver is formed into a ladder shape to secure the front view.

[Embodiment] Next, an embodiment of a forklift embodying the present invention will be described with reference to FIGS. 1 to 4. In the explanation, the structure around the vehicle body as well as around the mast is the same as that of various conventional forklifts.
The description will be omitted.

FIG. 1 is a schematic perspective view around a fork of a forklift 1 of the embodiment. As shown in the figure, a pair of left and right masts 3 are erected on a front portion of a vehicle body (not shown) of the forklift 1, and each mast 3 is composed of an outer mast 3a and an inner mast 3b. The outer mast 3a is provided to be tiltable back and forth by a tilt hydraulic cylinder (not shown). A bracket 5 is mounted between the left and right inner masts 3b so as to be able to move up and down along the mast 3. The lifting is performed by a hydraulic cylinder for lifting and lowering (not shown) provided along the mast 3 and a chain. .

As shown in FIG. 1, on the front surface of the bracket 5, two upper and lower finger bars 7 extending in the left-right direction and the left and right end face plates 9a and 9b fixed to the end surfaces thereof and the finger bars 7 are appropriately spaced. A frame composed of ribs 11 formed of
13 are arranged. And this frame 13 is the first
As shown in FIG. 2A of the sectional view taken along the line I-I of FIG.
In the engaging portion 5a protruding from the bracket 5, the pin 15,
Through the engagement piece 13a of the fixed flange 17 and the frame 13,
It is pivotally supported on the bracket 5 so as to be swingable around a pin 15. That is, the frame 13 moves up and down along the mast 3 integrally with the bracket 5 and swings around the pin 15 in the directions of arrows A and B in FIG.

On the front surface of the upper finger bar 7, flanges 19 and 21 are projected and fixed, and between the flange 19 and the end face plate 9a and between the flange 21 and the end face plate 9b, a columnar shape or a cylindrical shape extending in the left-right direction, respectively. The guide members 23 and 25 are installed. A left fork 27 and a right fork 29 are attached to each of the guide members 23, 25 so as to be movable in the left-right direction via sliding holes formed in their upper portions.

Each of the forks 27, 29 includes a hanging portion 27a, 29a extending downward from the sliding hole immediately in front of the finger bar 7 and a fork portion 27b, 29b bent from the lower end thereof and extending forward. Support rollers 27c and 29c that roll on the front surface of the lower finger bar 7 are provided on the lower rear surfaces of the 27a and 29a. When the frame 13 descends to the lowermost end, both fork parts 27b and 29b approach the ground, and when the outer mast 3a is tilted forward by the tilt hydraulic cylinder, the tips of both fork parts 27b and 29b reach the ground. It comes in contact.

A left fork 27 and a right fork 29 are provided in the left and right directions above and below the flanges 19 and 21 projecting from the front surface of the finger bar 7 so as to support the guide members 23 and 25, that is, in the directions of arrows C and D in FIG. An upper hydraulic cylinder 31 and a lower hydraulic cylinder 33 to be moved to are installed by fixing and fixing both ends of each main body 31a, 33a to each flange 19, 21. The rod 31b of the upper hydraulic cylinder 31 is attached to the left fork 27.
The rod 33b of the lower hydraulic cylinder 33 is attached to the upper end of the right fork 29 in the middle of the hanging portion 29a of the right fork 29.

Further, two arms 35 bent toward the mast 3 are attached to the upper surface of the finger bar 7 on both sides of the engagement piece 13a of the frame 13, and are shown in FIG. Two
As shown in the figure (B), each arm 35 and the bracket 5
Between the frame 13 and the left side hydraulic cylinder 37 for the cradle for swinging the frame 13 around the pin 15 of the bracket 5 in the directions of arrows A and B in the figure, the main bodies 37a and 39a are provided. Is pivotally supported on the upper surface of the engaging portion 5a of the bracket 5, and the tips of the rods 37b, 39b are pivotally supported on the lower surface of the arm 35.
It is arranged.

Furthermore, the forklift 1 according to the present embodiment includes both forks 27, 2.
A clamp mechanism 41 is provided on both sides of the mast 3 to press the load-bearing material placed on the sheet 9, for example, concrete piles, against the hanging parts 27a, 29a of the forks 27, 29. The clamp mechanism 41 includes a support block 43 standing on the upper surface of the finger bar 7 on the upper side of the frame 13, and an arm box 47 slidably accommodating a clamp arm 45. From both side surfaces of the arm box 47. Each of the engaging arms 49 projecting downward is pivotally supported by the support block 43 via the swing shaft 51, and the support block 43 and the arm box 47 are swingably engaged with each other.

Further, between the rear end of each arm box 47 and the finger bar 7 on the lower side of the frame 13, in order to swing each arm box 47 in the directions of arrows E and F in the drawing around the swing shaft 51 as a center. Clamp reach hydraulic cylinder 53
a is provided on the back surface of the lower finger bar 7 and the tip of the rod 53b is axially supported on the lower surface of the arm box 47, respectively. Also, inside the arm box 47, the clamp arm
A clamping hydraulic cylinder 55 for sliding 45 in the directions of arrows G and H in the figure fixes its main body 55a to the inner peripheral surface of the arm box 47, and the tip of the rod 55b is clamped to the clamp arm 45.
It is directly connected to the rear end and is built in.

Next, a side shift for moving the left fork 27 and the right fork 29 in the same direction in the left and right directions, a fork shift, a cradle for rocking the frame 13, a clamp reach for rocking the arm box 47, and both forks 27, 27. 2
A hydraulic circuit for driving and controlling the above-mentioned hydraulic cylinders for performing a clamp or the like for pressing the load-bearing object placed on 9 will be described with reference to FIGS. 3 and 4.

As shown in FIG. 3, this hydraulic circuit has a right fork.
29 fork shift first valve 57 and left fork
2nd valve 59 for 27 fork shifts and 2 forks
The third valve 61 for side shift of 7,29, the fourth valve 63 for cradle of the frame 13, the fifth valve 65 for clamp reach of the arm box 47, and the clamp of the load-bearing object by the clamp arm 45. Six four-port three-position manual switching valves of sixth valve 67 are used (see FIG. 4).

Of these, the first valve 57, the second valve 59, the fifth valve 65, and the sixth valve 67 perform lateral movement of each fork by using the engine 69 as its drive source, and clamp reach and clamp by the clamp mechanism 41. The sub-pump 71 and the tank 73, which have a sufficiently low hydraulic pressure feeding capacity, are connected via a manifold 75. On the other hand, the third valve 61 and the fourth valve 63 are main pumps 77 having a high hydraulic pumping capacity sufficient to carry out cargo handling operations such as lifting and lowering heavy objects, side shifts and cradle using the engine 69 as a drive source.
And the tank 73 via a manifold 79. The P port and T port of each valve are in communication with the P port and T port of each manifold 75, 79 connected to the corresponding pump and tank 73.

The above-mentioned cylinders and valves are connected as follows by relaying junction blocks 81 and 83 which divide the vehicle body side where fixed piping is provided and the lift side where movable piping is provided by a high pressure hose or the like.

In contrast to the lower hydraulic cylinder 33 that moves the right fork 29, the flow control valve with check valve is installed in the hydraulic chamber on the rod side.
The A port of the first valve 57 and the A port of the second valve 59 are connected via 85, and the non-rod side hydraulic chamber is connected to the B port of the first valve 57 via the flow rate adjusting valve 85. The A port of the third valve 61 is connected.

The A port of the first valve 57 and the A port of the second valve 59 are connected to the rod-side hydraulic chamber of the upper hydraulic cylinder 31 for moving the left fork 27 via a flow rate adjusting valve 85. In the hydraulic chamber on the non-rod side, the flow adjustment valve 85
Through the B port of the second valve 59 and the B port of the third valve 61.
The port is connected.

Right hydraulic cylinder for cradle that rocks frame 13
37, right hydraulic cylinder 3 for left hydraulic cylinder 39
The port A of the fourth valve 63 is connected to the rod side hydraulic chamber of 7 and the non-rod side hydraulic chamber of the left hydraulic cylinder 39 via the flow rate adjusting valve 85, respectively. B port of the fourth valve 63 is connected to the hydraulic chamber of the left hydraulic cylinder 39 and the hydraulic chamber on the rod side of the left hydraulic cylinder 39 via the flow rate adjusting valve 85, respectively.

For the clamp reach hydraulic cylinder 53 that swings the arm box 47, the A port of the fifth valve 65 is connected to the rod side hydraulic chamber via the flow rate adjusting valve 85, and the non rod side hydraulic chamber. To the fifth valve via the flow adjustment valve 85
65 B ports are connected.

Further, for the clamp hydraulic cylinder 55 that slides the clamp arm 45, the A port of the sixth valve 67 is connected to the hydraulic chamber on the rod side via the flow rate adjusting valve 85, and the hydraulic pressure on the non-rod side is Sixth valve through the flow control valve 85 to the chamber
67 B port is connected.

In the forklift 1 of the present embodiment having the above configuration, when the first valve 57 and the second valve 59 are switched so that oil is pumped to the A port, the rods of the upper hydraulic cylinder 31 and the lower hydraulic cylinder 33 are rod-shaped. Side sub-pump in the hydraulic chamber
Oil is made to flow in from 71, and rods 31b and 33b are made to enter the cylinder bodies 31a and 33a. Thus, the left fork 27
By moving the right fork 29 and the right fork 29 in the opposite directions of the arrows D and C in FIG. 1, the fork shift on the side of narrowing the fork is performed by the sub-pump 71 having a low hydraulic feed capacity. It

When the first valve 57 and the second valve 59 are switched so that the oil is pumped to the B port thereof, the oil is supplied from the sub-pump 71 to the non-rod side hydraulic chambers of the hydraulic cylinder 31 and the lower hydraulic cylinder 33. Flow into the cylinder body
The rods 31b and 33b are withdrawn from 31a and 33a. In this way, the left fork 27 and the right fork 29 are moved in the opposite directions of the arrows C and D in FIG. 1 so that the gap between them is widened, so that the fork shift on the side of widening the gap between both forks has a low hydraulic feed capacity. It is made by the sub-pump 71 which has.

On the other hand, when the third valve 61 is switched so that oil is pumped to its B port, oil is made to flow from the main pump 77 into the hydraulic chamber on the non-rod side of the upper hydraulic cylinder 31 from the cylinder body 31a to the rod 31b. And the oil in the rod-side hydraulic chamber of the upper hydraulic cylinder 31 is caused to flow into the rod-side hydraulic chamber of the lower hydraulic cylinder 33 to cause the rod 33b to enter the cylinder body 33a. Thus, the left fork 27 and the right fork 29 are respectively indicated by the arrow C in FIG.
The main pump 77 having a high hydraulic feed capacity has a side shift that moves both forks in the same direction (left direction) by moving the forks in the left direction.

When the third valve 61 is switched so that oil is pumped to its A port, oil is made to flow from the main pump 77 into the hydraulic chamber on the non-rod side of the lower hydraulic cylinder 33, and the oil is supplied from the cylinder body 33a to the rod. 33b is withdrawn, the oil in the rod-side hydraulic chamber of the lower hydraulic cylinder 33 is caused to flow into the rod-side hydraulic chamber of the upper hydraulic cylinder 31, and the rod 31b is made to enter the cylinder body 31a. Thus, the left fork 27 and the right fork 29 are respectively indicated by the arrow D in FIG.
By moving the fork in the right direction indicated by, the main pump 77 having a high hydraulic pressure feeding capability causes a side shift that moves both forks in the same direction (to the right).

As a result, since the fork shift in the light load state (the state in which no heavy object is placed) is covered by the sub-pump 71 having a low hydraulic feed capacity, it is easy to finely adjust the fork interval based on the decrease in the fork moving speed. It is possible to improve its usability. Further, since the main pump 77 can be put into a no-load state during the fork shift execution period, it is possible to reduce the load on the engine 69. Of course, the side shift can be preferably performed as in the conventional case.

Further, in the forklift 1 of the present embodiment, when the fifth valve 65 is switched so that the oil is pumped to the A port thereof, the oil is made to flow into the rod side hydraulic chambers of the left and right clamp reach hydraulic cylinders 53. The rod 53b into the cylinder body 53a. In this way, the arm boxes 47 respectively swing in the direction of arrow F in FIG.
45 is retracted above both forks 27 and 29, so both forks 2
It is possible to place heavy objects on 7,29 without any trouble.

Then, when the fifth valve 65 and the sixth valve 67 are switched so that oil is pumped to the B port after placing a heavy object or the like, the left and right clamp reach hydraulic cylinders 53 and the clamp hydraulic cylinder 55 are moved. Allow oil to flow into the hydraulic chamber on the non-rod side so that the rods 53b, 5
Exit 5b. In this way, the arm box 47 swings in the direction of arrow E in FIG. 1 and the clamp arm 45 is pulled toward both forks 27, 29, so that both forks 27,
Since the heavy object placed on 29 is clamped, it is possible to prevent the heavy object from being displaced from the fork even while the heavy object is being transported.

In addition, the forklift 1 according to the present embodiment has the fourth valve 63.
Is switched so that oil is pumped to its B port, oil is made to flow from the main pump 77 into the non-rod side hydraulic chamber of the cradle right hydraulic cylinder 37 and the rod side hydraulic chamber of the left hydraulic cylinder 39. Cylinder body 37
The rod 37b is withdrawn from the a and the rod 39b is entered into the cylinder body 39a, and the frame 13 is moved to the arrow A in FIG.
Rock in the direction. When the fourth valve 63 is switched so that oil is pumped to its A port, the oil is fed to the rod-side hydraulic chamber of the cradle right hydraulic cylinder 37 and the non-rod hydraulic chamber of the left hydraulic cylinder 39. To allow the rod 37b to enter the cylinder body 37a and to leave the rod 39b from the cylinder body 39a.
13 is swung in the direction of arrow B in FIG.

Thus, according to the forklift 1 of the present embodiment, which can perform the cradle that swings the frame 13,
Even when a long object such as a concrete pile is placed on both forks 27, 29 in a slightly tilted state, the cradle allows the long object to be vertically moved and transported. In other words, when a long object or the like is placed, it is not necessary to frequently perform a side shift and a fork shift to adjust the positions of both forks so that the fork can be placed horizontally, and the usability can be improved. .

Further, since the frame 13 which moves up and down along with the mast 3 together with the bracket 5 is composed of the upper and lower finger bars 7 and the ribs 11 between them, it is possible to secure a good front view of the driver while maintaining the strength thereof. .

[Effects of the Invention] As described in detail above with reference to the embodiments, according to the forklift of claim 1, the fork shift mainly carried out in the light load state (the state in which no heavy object is placed) is performed. Since it is covered by a sub-fluid pump with a low fluid pressure feed capacity that is separate from the main fluid pump used for cargo handling work, fine adjustment of the fork interval can be facilitated based on the decrease in the fork movement speed, and its usability can be improved. Alternatively, by using the main fluid pump having a high fluid pressure feeding capability, the side shift can be suitably performed as in the conventional case.

Further, according to the forklift of the second aspect, in addition to the above effects, the frame located in front of the driver is configured like a ladder, so that the driver's forward visibility can be well maintained while maintaining its strength. it can.

[Brief description of drawings]

FIG. 1 is a schematic perspective view of the fork and its periphery of the forklift 1 of the embodiment, FIG. 2 (A) is a sectional view taken along the line II of FIG. 1, and FIG. 2 (B) is II- of FIG. II line cross section, the third
FIG. 4 is a hydraulic circuit diagram of the forklift 1, and FIG. 4 is an explanatory diagram for explaining the configuration of each switching valve used in the hydraulic circuit. 1 ... Forklift, 3 ... Mast, 5 ... Bracket, 7 ... Finger bar, 11 ... Rib, 23, 25 ... Guide member, 27 ... Left fork, 29 ... Right fork, 31
...... Upper hydraulic cylinder, 33 …… Lower hydraulic cylinder, 77…
… Main pump, 71 …… Sub pump,

Claims (2)

[Claims] 1. A frame (13) is attached to a bracket (5) that moves up and down along a mast (3), and the frame (13) is attached.
Two forks (27,29) that are movable in the left-right direction are attached to the guide member (23,25) installed on the frame, and the two forks (27,29) are attached to the frame (13) to the left and right, respectively. Two fluid pressure cylinders (31, 33) for moving in the direction are provided, and a fluid pressure supply source for driving both fluid pressure cylinders (31, 33) to drive both cylinders and the two fluids. A first path of the fluid serving as a flow path for moving the two forks (27, 29) in the same left and right direction by the fluid pressure-fed from the fluid pressure source between the pressure cylinders (31, 33) Is provided
The fluid pressure source and the two fluid pressure cylinders (31, 33)
And a second path of the fluid, which serves as a flow path for moving the two forks (27, 29) in the left and right directions by the fluid to be pumped, From a main fluid pump (77) having a fluid pressure feeding capacity sufficient to carry heavy goods, and a sub fluid pump (71) having a fluid pressure feeding capacity sufficient to move the two forks (27, 29) alone. The forklift according to the present invention, wherein the main fluid pump (77) is connected to the first path, and the auxiliary fluid pump (71) is connected to the second path. 2. The forklift according to claim 1, wherein the frame (13) has a ladder shape in which a support frame (7) is provided with vertical ribs (11).