JPS61184267A - Hydraulic winch drive apparatus - Google Patents

Abstract

PURPOSE:To provide a hydraulic winch drive apparatus with high efficiency of cargo work by controlling the number of two variable capacity motors according to pressure set thereto. CONSTITUTION:Two variable capacity motors 3, 4 are connected to a winch drum. And to intake and discharge pipe paths 10, 31, 32 and 33 of both motors 3, 4 is connected a high and low speed change-over valve 8 which supplies pressurized liquid to both motors under at least set pressure, to only the first motor 3 under set pressure or less and shortcircuits said pipe paths with respect to the second motor 4. The respective motors 3, 4 are provided with constant horse power controlling valves 12, 14 which are constituted to change the respective motor speed according to the pressure in said pipe paths. Set pressure in the constant horse power controlling valves 12, 14 is set such that the set pressure in said valve 14 for the first motor is higher than that for the second motor and the set pressure in said valve 12 for the first motor is lower than that in said change-over valve 8.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a type of winch drive device in which a winch drum is driven by a plurality of hydraulic motors.

Conventional Technology In general, this type of hydraulic winch drive device is used for light load hoisting and light load
When lowering heavy loads, multiple hydraulic motors are connected in series for high-speed operation, and when lifting heavy loads, they are connected in parallel for low-speed operation.

For example, in the conventional device shown in FIG.
The hydraulic fluid from the directional control valve (7a), the % high/low speed control valve (72), and the check valve (731) of the counterbalance valve (731)
4), hydraulic motor (75), flow path (γ6), high/low speed switching valve (7η), flow path (7η), check valve (79) of counter balance valve (78), hydraulic motor # (80), flow path ( 8]
), (821) Directional switching valve (70J to tank (821)
When the directional control valve (70) is set to position B in order to lower the light load and heavy load, the working fluid from the pump (71) flows through the directional control valve (70J% flow path (76) , the hydraulic motor (751), the counterbalance valve (73), the high/low speed switching valve (721), and the direction switching valve (701). and hydraulic motor (80)
The liquid discharged from the counter balance valve (78J 1 flow path (
77), and circulates through the high/low speed switching valves (seven, flow paths (8)). In this case, the entire amount of hydraulic fluid from the pump (71) flows to the hydraulic motor (75), resulting in high-speed operation.

On the other hand, when hoisting a heavy load, when the directional control valve (70) is set at position A, the discharge pressure from the pump (7I) overcomes the setting spring of the high/low speed control valve (72), Switch to position 7 of hydraulic motor α5), (80)
Since the hydraulic motors are connected in parallel, the amount of inflow to each hydraulic motor is halved, resulting in low-speed operation.

Therefore, the above-mentioned conventional device has the 8th
As is clear from the figure, the load hoisting speed is in two stages: high speed for light loads and low speed for heavy loads.

The conventional device shown in FIG. 9 has a configuration in which one pump is added to the conventional device shown in FIG. 7, and the direction of the pump can be switched between two pumps and one pump using a switching valve. Therefore, in the illustrated state using one pump, the same two high and low hoisting speeds as shown in FIG. 7 are obtained;
When hoisting a light load using a single pump, the hydraulic motor (7 pumps) receives liquid discharged from both pumps and becomes even faster, so there are three hoisting speeds as shown in Figure 10. can get.

The hydraulic drive device described in JP-A-53-86981 is
At least one of the two hydraulic motors is a two-speed variable speed motor to increase the number of speed steps.

Problems to be Solved by the Invention Since the conventional equipment described above can only obtain hoisting speeds in several stages, the hoisting speed for medium loads, which is often used in cargo handling equipment, is intended for loads that are one step heavier than the hoisting load. Since the hoisting speed is , the cargo handling efficiency is poor under medium loads.

It is an object of the present invention to eliminate the above-mentioned drawbacks regardless of the speed range, and to improve safety when lowering a single heavy load and reduce energy loss due to motor idling.

Means for Solving the Problems The structure of the present invention for achieving the above object will be explained below using FIGS. 1 to 6, which correspond to embodiments.

Connected to the same winch drum and counterbalanced valve (
The first variable displacement hydraulic motor (3), which is equipped with a counterbalance valve (5), and the second variable displacement hydraulic motor (4), which is equipped with a counterbalance valve (force), are connected to the hydraulic pressure via a directional valve (2). When the motor supply pressure exceeds the set pressure, both variable displacement hydraulic motors (3) are connected to the source (1). ).

(4) are connected from series to parallel, and when the pressure is below the set pressure, only the second variable displacement hydraulic motor (4) is connected to the inflow and outflow passages (9) on both sides.
, α0) is provided with a high/low speed switching valve (8) that short-circuits the counterbalance valve (including force), and the variable capacity forming pressure motors (3) and (4) are equipped with setting springs (2, f25
) through the spools (i6), (17) exceeds the set pressure by the setting springs (24), (251), the pressure liquid is transferred to the variable capacity forming pressure motors (3), (4).
) volume adjustment mechanism (13, (15) large capacity switching chamber (4)
6), (4UK, When the pressure is below the set pressure, the pressure liquid is guided to the small capacity switching chambers (44), '(45), and when the liquid pressure and the set pressure are balanced, the high capacity switching chambers (46)j (47) and Constant horsepower control valves (12) and (14) are provided to control the variable capacity forming pressure motors (3) and (4) at constant horsepower by blocking the small capacity switching chambers (44) and 451, respectively. Further, the constant horsepower control valve (12) provided on the first variable leaf type hydraulic motor (3) is set with the motor supply pressure when lifting the load and the braking pressure when lowering the load via the spool (+6). Spring (2IO and opposing circuit (49) t (5)
) t (22), and a second variable displacement hydraulic motor (
4) A constant horsepower control valve (14J) controls the motor supply pressure only when the motor supply pressure when lifting a load exceeds the set pressure of the high/low speed switching valve (8), and controls the motor braking pressure when lowering the load. A circuit 68), (60) + +23) is provided to oppose the setting spring (25) via (17), and the constant horsepower control valve (1 set pressure is connected to the constant horsepower control valve (14)
is set higher than the set pressure of the high/low speed switching valve (8) and lower than the set pressure of the high/low speed switching valve (8).

When hoisting a working load, the motor supply pressure is controlled by the high/low speed switching valve (8
) below the set pressure (load i in Figure 5), the high/low speed switching valve (8) assumes position a, and the entire amount of hydraulic fluid from the hydraulic pressure source (1) is transferred to the first variable displacement hydraulic motor. (3), the first variable displacement hydraulic motor (3) hoists the load, and passes the load to the second variable displacement hydraulic motor (3) via the winch drum.
4) Drive.

At that time, the constant horsepower control valve of the second variable displacement hydraulic motor (4) is set at the rest position a where only the pressing force of the spool (spring C5 set to 1η) is applied, and the second variable displacement hydraulic motor (4) pumps at minimum capacity.

On the other hand, when the constant horsepower control valve (12) of the first variable displacement hydraulic motor (3) position a
, the first variable displacement hydraulic motor (3) becomes the minimum displacement and hoists the load at high speed.

For light and medium loads (loads A-B in Figure 5), the position is reached when the motor supply pressure is higher than the set pressure, so the capacity of the first variable displacement hydraulic motor (3) increases, and the load accordingly increases. As the hoisting speed decreases, the motor supply pressure also decreases, and when this motor supply pressure is balanced with the set pressure, the motor capacity and motor supply pressure become constant. Conversely, when the motor supply pressure is below the set pressure, it takes position a, so the motor capacity decreases, the load hoisting speed increases and the motor supply pressure increases, and the motor supply pressure becomes equal to the set pressure. When balanced, the motor capacity and motor supply pressure become constant.

Next, when the load increases beyond load B, the capacity of the first variable displacement hydraulic motor (3) has already reached its maximum capacity under load B, so the motor supply pressure increases, and the pressure increases. When the set pressure of the low speed switching valve (8) is exceeded, the high/low speed switching valve (8) is switched to the position as shown in Fig. 6, and the hydraulic pressure source (1) is switched to the position shown in Fig. 6.
The hydraulic fluid from the first variable displacement hydraulic motor (3) and the second
The flow is divided to the variable displacement hydraulic motor (4), and the load is hoisted by these two hydraulic motors (3) and (4). The motor supply pressure at that time becomes equal to the pressure of the load i, that is, the set pressure of the constant horsepower control valve (14), as shown in FIG. 6(c).

The capacity of the first variable displacement hydraulic motor (3) is the minimum capacity because the motor supply pressure is lower than the set pressure of the constant horsepower control valve (121) as shown in Fig. 6 (a). The capacity of the displacement type hydraulic motor (4) is the capacity required to hoist the load i at the set pressure of the constant horsepower control valve (+4) as shown in Fig. 6 (b), and is slightly larger than the minimum capacity. Large.Furthermore, the load is load i
, the second variable displacement hydraulic motor (4)
The capacity increases, and reaches its maximum capacity when the load is C or higher. On the other hand, the capacity of the first variable displacement hydraulic motor (3) is shown in Fig. 6 (
As shown in (a) and (c), when the load exceeds the load -, the constant horsepower control valve (12) is activated and the capacity increases from the minimum capacity to the maximum capacity under heavy load. Furthermore, when a load greater than a heavy load is hoisted, the capacities of the hydraulic motors (3) and (4) reach their maximum capacities, so the motor supply pressure increases.

Next, when the directional control valve (2) is switched to position B to lower the load, the entire amount of hydraulic fluid from the hydraulic pressure source (1) is transferred to the first variable displacement hydraulic motor (3) as shown in FIG. ),
The discharged liquid passes through the counterbalance valve (5) to the hydraulic pressure source (1).
reflux into the tank. In this case, when the load is below heavy load C, as shown in Fig. 6 (f), the constant horsepower control valve (one setting pressure of the first variable displacement hydraulic motor (3) is higher than the motor braking pressure, so the hydraulic motor ( 3) is maintained at minimum capacity and lowers the load at high speed.

For heavy load F-E, motor braking pressure and constant horsepower control valve (121
When the set pressure is balanced with the set pressure, constant horsepower control is performed to keep the motor braking pressure constant.

On the other hand, the second variable displacement hydraulic motor (4) is driven by the load and pumps, and its working fluid circulates through a circulation path that includes a counterbalance valve (7). Since the motor braking pressure acts on the spool (17), when the load of the second variable displacement hydraulic motor (4) is below G, the motor braking pressure is lowered by the constant horsepower control valve (■( Since it is lower than the set pressure in (a), the capacity is not the minimum capacity.At heavy loads G-ψ, constant horsepower control is performed where the motor braking pressure becomes constant when the motor braking pressure and set pressure are balanced, and at heavy loads t-
At E, the motor braking pressure is higher than the set pressure, resulting in the maximum capacity.

Embodiments An embodiment of the present invention will be described with reference to the drawings. In Fig. 1, (1) is a hydraulic pressure source, (2) is a directional valve, (3) is a first variable displacement hydraulic motor, and (4) is a second variable displacement hydraulic motor. The pressure motors are connected to the same winch drum (not shown) via gears or the like. The first variable displacement hydraulic motor (3) is equipped with a counterbalance valve (5), and the second variable displacement hydraulic motor (4) is equipped with a counterbalance valve (power). (
A high/low speed switching valve (8) is arranged between 5), (7) and the directional switching valve (2). When the motor supply pressure exceeds the set pressure, this high/low speed switching valve switches the position between the first variable displacement hydraulic motor (3) and the second variable displacement hydraulic motor (4).
are connected in series to parallel, and when the motor supply pressure is less than the set pressure, it takes position a and short-circuits both the inflow and outflow passages (9L (1, 0) of the second variable displacement hydraulic motor (4)). .

The high/low speed switching valve (8) is provided with a holding circuit (1υ) to maintain the position even if the pressure decreases when switching to the position.

(12) is a constant horsepower control valve that controls the volume adjustment mechanism 0□□□ of the first variable displacement hydraulic motor (3), and the circle is the volume adjustment mechanism (151) of the second variable displacement hydraulic motor (4). Constant horsepower control valve (IL) (1 (A) is the spool Q6), (17) has a spring (1) set to a predetermined spring force at one end, (19) and the spool ( 1
6), the piston (20) that presses (17), (2υ
A cylinder (221, (23) with
A liquid chamber (28), (27) equipped with a large diameter piston (26), (27) that presses the spring of
29).

Therefore, the P port is connected to the variable capacity forming pressure motor (3), (
4) and the counterbalance valve (5), check valve (61, (30) of (7)) (311t (32)
and the variable capacity forming pressure motor (3), the shuttle valve (35
)t f36), the R port communicates with the tank (3(to)) through the flow path '3n * (38), the A and B ports connect to the flow path, (41),
(Volume adjustment mechanism (13) by 43, small capacity switching chamber (44) of f151, (451 and large capacity switching chamber (46)
)? (47) is connected.

The inner chamber of the constant horsepower control valve (12 cylinders (221) is connected to the flow path (33) through the passage (49),
The outer chamber (50) and the liquid chamber (c) are connected to a passage (51),
(521 is connected to flow path 01).

The constant horsepower control valve 0 force liquid chamber (29) passes through the passage (56) to the flow passage (321), the inner chamber 6η of the cylinder (23) passes through the passage (58) to the flow passage 00, and the outer chamber (59) ) is the passage (
It communicates with the flow path (34) via (60) and (56).

Therefore, the set pressure of the constant horsepower control valve (121) is much higher than that of the constant horsepower control valve (14), and the high/low speed switching valve (8
) is set lower than the set pressure.

Since this embodiment has the above-described configuration, when the directional control valve (2) is switched to position A to hoist the load, the operation is as follows. When the motor supply pressure from the fluid pressure source (1) is less than the set pressure of the high/low speed switching valve (8), the high/low speed switching valve (8)
is at position a, and the supply/discharge passage (9) of the second variable displacement hydraulic motor (4) (hereinafter referred to as hydraulic motor (4)) t (1
0) is short-circuited, the hydraulic fluid from the hydraulic pressure source (1) is transferred to the second
As shown in the figure, the flow path (6I), directional switching valve (2), flow path (6L high/low speed switching valve (8), flow path 64), check valve (
6), the first variable displacement hydraulic motor (3) via the flow path Gυ
(hereinafter referred to as the hydraulic motor (3)), and the returned liquid is returned to the tank of the hydraulic pressure source (1) via the flow path (33), the directional control valve (2), and the flow path (63). The hydraulic motor (3) drives the winch drum and the hydraulic motor (4), while
The hydraulic motor (4) pumps and the working fluid is pumped through the hydraulic motor (4), the flow path aO), the high/low speed switching valve (8), and the flow path (
It circulates through the circulation path formed in step 9).

In this case, the hydraulic motor (3) has a minimum capacity depending on the constant horsepower control valve a for light loads (loads A and below in Figure 5), and for light and medium loads (loads A-B in Figure 5), depending on the load. The hydraulic motor (4) is set to the minimum capacity by the constant horsepower control valve (I4).

That is, the motor supply pressure is guided to the liquid chamber (28) of the constant horsepower control valve 02) and the outer chamber (50) of the cylinder control valve 22), and the inner chamber (481) is connected to the passage (49), the flow path brass, and the direction switch. Valve (2
), which communicates with the tank of the hydraulic pressure source (1) via the flow path (631).Therefore, in the constant horsepower control valve (12), the spring (I
8) and the spool pressing force of the piston (20) and the spring (24) set to a specified spring force by the large diameter piston (26).
J and J oppose each other via the spool ([6), and since the spring (241) is stronger under light loads, the constant horsepower control valve (12) takes position a and closes the small capacity switching chamber ([241] of the volume adjustment mechanism (13)). 44
) and communicates the large-capacity switching chamber (46) with the tank. As a result, the hydraulic motor (3) hoists a light load A or less at high speed with minimum capacity. At light and medium loads A-B, the motor supply pressure increases due to the increase in load and overcomes the spool pressing force on the piston (20) side and the pressing force of the spring.
The constant horsepower control valve (12) is located in the large capacity switching chamber (
46) to communicate the small capacity switching chamber (44) to the tank, the capacity of the hydraulic motor (3) increases, and as a result, the load hoisting speed decreases and the motor supply pressure decreases. descend. As a result, when the pressing forces at both ends of the spool ([6] are balanced, the constant horsepower control valve (12J) takes the neutral position and closes the small capacity switching chamber (44) and the large capacity switching chamber (46), so that the hydraulic motor ( 3), the capacity and motor supply pressure become constant. When the load decreases from this neutral state, the motor supply pressure decreases, and the constant horsepower control valve (12) changes to position a, and the small capacity switching chamber (44) transfers the motor, Large capacity switching chamber (
46) to the tank, the capacity of the hydraulic motor (3) decreases, and as a result, the hoisting speed increases and the motor supply pressure increases. As a result, when the pressing forces at both ends of the spool (16) are balanced, the constant horsepower control valve (12) assumes a neutral position, so that the capacity of the hydraulic motor (3) and the motor supply pressure become constant.

That is, at light loads A and below, the capacity of the hydraulic motor (3) becomes minimum and high-speed hoisting is performed, but at light and medium loads A to B, constant horsepower characteristics are obtained.

On the other hand, the constant horsepower control valve (14) of the pumping hydraulic motor (4) is operated by the piston (21) of the cylinder (23) due to the differential pressure between the suction side flow path (3) and the discharge side flow path (10). ) is moving in the opposite direction to the shuttle valve (
The hydraulic fluid in the flow path (10) flowing through the flow path (10) is led to the small capacity switching chamber (45) and the large capacity switching chamber (47) is connected to the tank (36).
9), the hydraulic motor (4) has the minimum capacity.

Next, when the load exceeds load B at which the capacity of the hydraulic motor (3) is maximum, the supply pressure of the hydraulic motor (3) increases, and this pressure exceeds the set pressure of the high/low speed switching valve (8). If you cross it, the 6th
As shown in the figure, the high/low speed switching valve (8) is switched to the position, and the hydraulic fluid from the hydraulic pressure source (1) passes through the directional switching valve (2) and the high/low speed switching valve (8) to the flow path ( The hydraulic motor (3) is arranged in parallel with the flow divided into (54) and (9).

(4) and discharged from both hydraulic motors pass through the flow path (33)l (10) and merge before the directional control valve (2). Since the flow returns to the tank of the hydraulic pressure source (1) through the passage (63), the hydraulic motor (3)
, (4) will drive the winch drum.

In this case, the supply pressure of the hydraulic motor (3) is constant horsepower control valve 0.
The constant horsepower control valve (12), whose set pressure is higher than the set pressure of constant horsepower control valve α, takes position a and directs the pump hydraulic pressure to the small capacity switching chamber (44) for large capacity switching. Room (4
6) to the tank (39), the hydraulic motor (3
) decreases to the minimum capacity (load i). At this time, the hydraulic motor (4) has a capacity necessary to hoist the load i at the set pressure of the constant horsepower control valve (14), which is slightly larger than the minimum capacity.

When the load increases more than the load l, the constant horsepower control valve (14
) operates to perform constant horsepower control, increasing the capacity of the hydraulic motor (4) and keeping the motor supply pressure constant. When the load exceeds the load C at which the capacity of the hydraulic motor (4) is maximum, the motor supply pressure increases and the pressure is adjusted to the constant horsepower control valve (12).
When the pressure exceeds the set pressure (1), the constant horsepower control valve (1) operates, increasing the capacity of the hydraulic motor (3) and keeping the motor supply pressure constant.

That is, when the load increases beyond the load d, the motor supply pressure increases and when the hydraulic pressure exceeds the set pressure of the constant horsepower control valve Q4), the spool 0D resists the pressing force of the spring 2 (G). The shuttle valve (36) switches the motor supply pressure to the position.
The constant horsepower control valve (14) and the flow path (43) lead to the large capacity switching chamber (47) of the volume adjustment mechanism (1), and the small capacity switching chamber (4 channels) Valve (I4), flow path (
38) to the tank (39), the capacity of the hydraulic motor (4) increases, reducing the motor supply pressure and returning the spool (Iη) of the horsepower control valve (I4) to the neutral position.

In this way, the capacity of the hydraulic motor (4) increases as the load increases, thereby maintaining the supply pressure constant. During this time, the hydraulic motor (3) is operated by the constant horsepower control valve (121) because the set pressure of the constant horsepower control valve (121) is higher than the set pressure of the constant horsepower control valve (121).
121 is at position a and maintains the minimum capacity. When the load reaches heavy load C, the capacity of the hydraulic motor (4) becomes maximum. Furthermore, if the load increases beyond the heavy load C, the motor supply pressure increases and becomes equal to the set pressure of the heavy load iron horsepower control valve (12). If the load increases beyond the load -, the spool (16) switches to a position against the pressing force of the spring e41, increasing the capacity of the hydraulic motor (3) as described above and increasing the motor supply pressure. To keep it constant, the hoisting speed of the load is reduced. Conversely, if the load decreases, the hydraulic motor (
3) capacity decreases and load hoisting speed increases.

When the load reaches a heavy load, the capacity of the hydraulic motor (3) becomes maximum. Furthermore, when a load greater than a heavy load is hoisted, the capacity of each hydraulic motor (3), (4) is at its maximum capacity, so the motor supply pressure increases.

Next, when the directional control valve (2) is switched to position B in order to lower the load, the entire amount of hydraulic fluid from the hydraulic pressure source (1) is transferred to the flow path f61), the directional control valve ( 2), flow path (
33) and flows into the hydraulic motor (3), and the discharged liquid passes through the counterbalance valve (5), the flow path (54), the high/low speed switching valve (8), the flow path (62), and the directional switching valve ( 2), as it returns to the tank of the hydraulic pressure source (1) via the flow path (63),
The hydraulic motor (3) lowers the load. In this load lowering, the motor braking pressure upstream of the counterbalance valve (5) is applied to the large diameter piston (26) of the constant horsepower control valve (12), and the spring (24+) is set to a specified spring force, and the cylinder (221 into the outer chamber (50), while the inner chamber (4
The motor supply pressure from the flow path (337>-) is guided to 81. Therefore, the motor braking pressure is controlled by the constant horsepower control valve (12).
For a load smaller than load F, which is the set pressure of
), the hydraulic motor (3) has the minimum capacity and lowers the load at high speed. In addition, when the load exceeds the load F, the constant horsepower control valve a2 is activated, and the capacity of the hydraulic motor (3) increases or decreases as the load increases or decreases, performing constant horsepower control and lowering the load. The speed is as shown in FIG. 5, and the motor braking pressure is kept constant.

On the other hand, the hydraulic motor (4) is driven by the load and pumps, and the hydraulic fluid is pumped through the hydraulic motor (4), the flow path (9), the counterbalance valve (7), the high/low speed switching valve (8), and the flow path. 0
0). The liquid chamber (29) and cylinder (23) on the constant horsepower control valve side during this load lowering.
) The counterbalance valve (motor braking pressure on the upstream side acts on the outer chamber (59) of The spool pressing force due to the spring aω and the spring (the two pressing forces oppose each other via the spool (17). In this case, the load on the constant horsepower control valve side is as shown in Fig. 6 (to)
The hydraulic motor (4) assumes position a when the load G is below.
has the minimum capacity as shown in FIG. 6(e). Load G~ψ
Then, constant horsepower control is performed, and the capacity of the hydraulic motor (4) increases or decreases as the load increases or decreases, and the maximum capacity is maintained at loads - to E.

In this case, when lowering a light load or a load in the garden, the hydraulic motor (4) becomes the minimum capacity, reducing the resistance during idling, and when lowering a heavy load, the increase in motor braking pressure is limited, making it safe. You can increase your sexuality.

Diagram M5 shows a load-speed characteristic diagram of this example. As mentioned above, when hoisting a garden load A-B where the motor supply pressure is less than the set pressure of the high-low speed switching valve (83), the hydraulic motor (3) is under constant horsepower control, and the hydraulic motor (4) is under constant horsepower control. As shown in (b), both hydraulic motors (3) and (4) are pumped at the minimum capacity and when hoisting medium/heavy loads i-D where the motor supply pressure exceeds the set pressure of the high/low speed switching valve (8). With constant horsepower control in parallel arrangement, the hydraulic motor (4) performs constant horsepower control when the load is d-c, and the hydraulic motor (3) performs constant horsepower control when the load is between D and D. The hoisting speed of the load A-D can be increased to the constant horsepower curve of the hydraulic motor shown in FIG. 5, and can be changed substantially continuously after reaching the constant horsepower curve.

Effects of the Invention As is clear from the above explanation, according to the present invention, when hoisting light and heavy loads A-H shown in FIG. For winding D, two variable capacity forming pressure motors are arranged in parallel,
For heavy loads I to C, the second variable displacement hydraulic motor is controlled at constant horsepower, and for heavy loads C to D, the first variable displacement hydraulic motor is controlled at constant horsepower to adjust the hoisting speed to a wide and narrow speed range. Since the horsepower curve can be varied steplessly regardless of the constant horsepower curve, it eliminates the disadvantage of conventional equipment that uses multiple hydraulic motors and can only obtain stepwise load-speed characteristics, and can be used in the intermediate load range. can significantly improve cargo handling efficiency.

In addition, for lowering light loads A and below and light and heavy loads A-F, the first
The variable displacement hydraulic motor has the smallest capacity and lowers the load at high speed, improving cargo handling efficiency when lowering the load, and the second variable displacement hydraulic motor has the maximum capacity when lowering the heavy load ψ~E. As a result, large braking pressure can be obtained and the load can be safely supported. Further, in hoisting and lowering of light loads A and below and light and heavy loads A to G, the pumping second variable displacement hydraulic motor has the minimum capacity and the idling flow rate is small, so that the loss of energy is small.

[Brief explanation of the drawing]

Fig. 1 is a hydraulic circuit diagram showing an embodiment of the present invention, Figs. 2, 3, and 4 are explanatory diagrams of the operation of this embodiment, and Fig. 2 is a hydraulic circuit for lifting light loads and light and heavy loads. Figure 3 is a hydraulic circuit diagram for lifting light and heavy loads, Figure 4 is a hydraulic circuit diagram for lowering a load, and Figure 5 shows the relationship between load and load lifting/lowering speed in the present invention. Figure 6 (a) is a diagram showing the relationship between the load and the capacity of the hydraulic motor (3) when hoisting, and Figure 6 (b) is a graph showing the relationship between the load and the capacity of the hydraulic motor (4) when hoisting. Figure 6 (c) is a diagram showing the relationship between the load and motor supply pressure, and Figure 6 (c) is a diagram showing the relationship between the load and the capacity of the hydraulic motor (3) when lowering. Figure 6 (e) is a diagram showing the relationship between the load and the capacity of the hydraulic motor (4) during lowering, Figure 6 (f) is a diagram showing the relationship between the load and motor braking pressure, Fig. 7 is a hydraulic circuit diagram of the conventional device, Fig. 8 is a chart showing the relationship between the load and load hoisting and lowering speed of the conventional device shown in Fig. 7, and Fig. 9 is a hydraulic circuit diagram of another conventional device. , FIG. 10 is a chart showing the relationship between the load and the load hoisting/lowering speed of the conventional device shown in FIG. 9. DESCRIPTION OF SYMBOLS 1... Hydraulic pressure source, 2... Directional switching valve, 3... First variable displacement hydraulic motor, 4... Second variable displacement hydraulic motor, 5, 7... Counter balance Valve, 8...High/low speed switching valve, 12.14...Constant horsepower control valve, 16°15.
...Volume adjustment mechanism, 16.17... Spool, 24.
25...Spring, 44.45...Small capacity switching chamber, 46
．． 47...Large capacity switching room. Figure 7 Figure 8 Figure 9

Claims (1)

[Claims] A first variable displacement hydraulic motor and a second variable displacement hydraulic motor, each connected to the same winch drum and each equipped with a counterbalance valve, are connected to a hydraulic pressure source via a directional valve, and each variable displacement hydraulic motor is connected to a hydraulic pressure source via a directional valve. Between the hydraulic motor and the directional valve,
When the motor supply pressure exceeds the set pressure, both variable displacement hydraulic motors are connected from series to parallel, and when the motor supply pressure is below the set pressure, only the second variable displacement hydraulic motor short-circuits both its inflow and outflow pipes, including the counterbalance valve. In addition to providing a high/low speed switching valve, each variable displacement hydraulic motor is equipped with a pressure fluid that, when the hydraulic pressure exceeds the set pressure, is transferred to the large capacity switching chamber of the variable displacement hydraulic motor's volume adjustment mechanism below the set pressure. In this case, a constant horsepower control valve is installed which guides the pressure liquid into the small capacity switching chamber and closes off the large capacity switching chamber and the small capacity switching chamber when the liquid pressure and the set pressure are balanced. The constant horsepower control valve provided on the hydraulic motor is equipped with a circuit that guides the motor supply pressure when hoisting a load and the braking pressure when lowering a load, and the constant horsepower control valve provided on the second variable displacement hydraulic motor receives the A circuit is provided to guide the motor supply pressure only when the motor supply pressure exceeds the set pressure of the high/low speed switching valve during hoisting, and a circuit that guides the motor braking pressure during load lowering. A hydraulic winch characterized in that the set pressure of the control valve is set higher than the set pressure of the constant horsepower control valve provided on the second variable displacement hydraulic motor and lower than the set pressure of the high-low speed switching valve. Drive device.