KR20230062926A - Construction machinery to reduce energy during boom down movement - Google Patents

Abstract

The present invention relates to a construction machinery that operates with a hydraulic system, such as an excavator, and specifically to the construction machinery provided with a variable drain check valve that has a variable back pressure so that energy can be saved when the boom is down depending on a work type of the excavator. The construction machinery according to the present invention to achieve the above purpose includes a variable drain check valve that increases a back pressure by adding the pressure of hydraulic oil flowing inside through a port to elastic force of a built-in coil spring when a boom down lever is operated, wherein a flow rate of a pump is reduced by a negative hydraulic signal due to an increase in back pressure of the variable drain check valve.

Description

Construction machinery to reduce energy during boom down movement}

The present invention relates to a construction machine that operates with a hydraulic system, such as an excavator, and more particularly, to a construction machine for reducing energy during a boom-down operation in which back pressure is variable so as to save energy when the boom is down according to the work type of the excavator. will be.

Since construction equipment used in civil engineering or construction work must be always moved at the construction site, it must be suitable for movement.

In general, construction machinery is often used violently at construction sites, and is often used in bad weather conditions or in non-stop locations, so construction machinery must have fewer breakdowns and excellent durability.

An excavator, a type of construction machine, consists of a moving body, a swinging body mounted on the moving body, and a work device installed on the swinging body. Perform crushing work for dismantling and leveling work for clearing the ground.

The excavator's work equipment is a boom installed on the swing body and installed to be able to move up and down based on the part supported on the swing body, and one end side installed on the boom and installed to be stretchable in the form of unfolding or folding with respect to the boom It includes an arm and a bucket oscillatingly installed on the other end side of the arm, and operates by hydraulic pressure.

The boom of an excavator is moved by a cylinder, and the cylinder is operated by hydraulic oil supplied to one side and the other side. At this time, the boom can descend by its own weight even if hydraulic oil is not supplied to the cylinder until the boom descends and touches the ground.

However, excavators generally have a disadvantage in that energy is wasted because hydraulic fluid is supplied to the cylinder even when the boom descends.

In the drawings, FIG. 1 is a conceptual diagram of a hydraulic circuit when an RCV lever operating a boom cylinder of an excavator according to the prior art is in a neutral position, FIG. 2 is a conceptual diagram of a hydraulic circuit when the boom is in an up state, and FIG. 3 is in a boom down state It is a conceptual diagram of the hydraulic circuit at the time.

As shown in FIGS. 1 to 3, while the spool 3 is controlled by the RCV lever 1, the hydraulic oil flows through the front chamber 11F or the rear chamber 11B of the cylinder 10 by the operation of the swash plate pump 5. The stroke of the cylinder 10 expands and contracts as it flows in or out, and the boom rises or falls as the cylinder 10 expands or contracts.

On the other hand, when the RCV lever (1) is located in a neutral state, the RCV pressure is not applied to the spool (3), so the spool (3) is fixed in the middle position as shown in FIG.

In this case, the hydraulic oil supplied by the operation of the pump 5 proceeds to the negative orifice 21 along the neutral flow path of the spool 3. When a large flow rate passes through the negative orifice 21, a negative pressure signal 21S is generated. will rise

When the negative pressure signal 21S rises, the pump regulator 23 reduces the flow rate of the pump 5 by the increased negative pressure signal 21S. At this time, back pressure is formed in the drain check valve 30 mounted on the downstream side of the negative orifice 21 by working oil.

As shown in FIG. 2, when the operator moves the RCV lever 1 from the neutral state to the boom-up state for boom-up operation, the RCV pressure presses one side of the spool 3, and the spool 3 generates an RCV pressure signal will move proportionally.

When the spool (3) moves, before it is completely switched, some of the neutral passage is open, and the flow rate of the pump (5) opens the check valve (31) and passes through the passage of the spool (3) to the rear chamber (11B) of the cylinder (10). The stroke of the cylinder 10 is extended and the boom rises.

On the other hand, according to the extension of the stroke of the cylinder 10, the hydraulic oil in the front chamber 11F of the cylinder 10 flows out, and the hydraulic oil that flows out is drained through the flow path of the spool 3 and drained through the drain check valve 30 to the drain tank. It flows to (13).

At this time, as the hydraulic fluid flowing out through some of the neutral passages flows into the negative orifice 21, the negative pressure signal 21S formed lower than the negative pressure signal 21S at the neutral position (state of FIG. 1) described above is applied to the pump regulator. It is input to (23) and the discharge flow rate of the pump 5 is determined to be higher than the neutral position in FIG.

At this time, the fluid flowing through the drain check valve 30 flows as the fluid passing through the negative orifice 21 and the fluid flowing out from the front chamber 11F of the boom cylinder 10 are added. Therefore, a larger flow rate than in the neutral state of FIG. 1 flows to the drain check valve 30, so that the back pressure rises.

In addition, when the spool (3) is completely switched, the neutral flow path is completely blocked, and the entire flow rate of the pump (5) opens the check valve (31) and passes through the flow path of the spool (3) to the rear chamber (11B) of the cylinder (10). , the stroke of the cylinder 10 is extended and the boom rises, and since there is no fluid flowing to the negative 21, the negative pressure signal 21S becomes very low.

On the other hand, the stroke of the cylinder 10 extends at a faster speed than the state before the spool 3 is completely switched, and flows out of the front chamber 11F of the cylinder 10 and drains through the flow path of the spool 3, The amount of fluid flowing through the check valve 30 is also greater than before the spool 3 is completely switched.

As a result, the fluid flowing through the drain check valve 30 increases and the back pressure rises, and the negative pressure signal 21S partially rises by flowing backward through the negative orifice 21, but the pressure rise is not large, so the pump 5 discharges The effect on the flow rate is insignificant.

As shown in FIG. 3, when the operator positions the RCV lever 1 in the boom-down position, RCV pressure is applied to the other side of the spool 3 and the position of the spool 3 proportionally moves according to the RCV pressure signal.

When the spool (3) moves, before it is completely switched, a part of the neutral flow path is open, and the flow rate of the pump (5) opens the check valve (31) and passes through the flow path of the spool (3) to the front chamber (11F) of the cylinder (10). The stroke of the cylinder 10 is contracted and the boom descends.

At this time, in the case of the boom cylinder 10, it is accelerated by energy according to its own weight and accelerates more than the acceleration by the flow rate of hydraulic oil supplied from the pump 5, and according to the area ratio of the cylinder 10, the rear chamber 11B of the cylinder 10 In , a large amount of hydraulic oil is drained through the passage of the spool (3) and flows into the drain tank (13) through the drain check valve (30). At this time, the fluid that has passed through the negative orifice 21 also flows into the drain check valve 30 . Therefore, in the case of the boom lowering operation of FIG. 3 , a greater amount of flow flows to the drain check valve 30 than the boom raising operation of FIG. 2 .

In addition, when the spool (3) is completely switched during the boom-down operation, the neutral flow path is completely blocked or partially opened, and most of the flow rate of the pump (5) opens the check valve (31) and passes through the flow path of the spool (3) to the cylinder. It flows into the front chamber 11F of (10). Since the cylinder 10 is accelerated by potential energy by its own weight and the flow rate of the pump 5 and contracts at a high speed, in the rear chamber 11B of the cylinder 10, a larger flow rate than the boom lifting operation moves the spool 3 through the drain check valve 30.

In general, in an excavator, when the change in back pressure due to the amount of fluid flowing through the drain check valve 30 is large, the energy loss due to the pressure increase and the discharge flow rate of the pump 5 decrease due to the increase of the negative pressure signal 21S Since a decrease in speed or the like may occur, it is common to keep the pressure increase ratio (override characteristic) to the flow rate passing through the drain check valve 30 low. Therefore, in a general excavator, even if the flow rate through the drain check valve 30 is different in the boom raising operation of FIG. 2 or the boom lowering operation of FIG.

Therefore, even if the drain flow rate of the hydraulic oil flowing out of the rear chamber 11B of the cylinder 10 in the boom down operation is high, the back pressure by the drain check valve 30 is low, and consequently, the negative pressure signal 21S does not change significantly, so that the pump ( 5) is to discharge the hydraulic oil at the set flow rate of the pump (5).

On the other hand, when the boom touches the ground and lifts the upper body of the excavator during the jack-up operation, the self-weight energy of the boom cylinder is dissipated, so the speed of the boom cylinder is higher than when it comes down in the air (in the boom-down state where energy due to its own weight is applied). It gets lower.

Therefore, although the flow rate of the rear chamber 11B of the cylinder 10 is reduced, the change in the back pressure of the drain check valve 30 is small according to the difference in flow rate, so the discharge flow rate of the pump 5 is not significantly different from when the boom is down.

Republic of Korea Patent Publication No. 2002-0093129 (published on December 12, 2002) Republic of Korea Patent Publication No. 10-2015-0058279 (published on May 28, 2015) Japanese Publication Patent Publication No. 8-510813 (published on November 12, 1996)

The present invention was invented to solve the problems of the prior art as described above, and construction machinery for energy reduction during boom down operation capable of controlling the back pressure of the drain check valve so that the boom down or jack up operation can be performed smoothly Its purpose is to provide

In the construction machine according to the present invention for achieving the above object, when the boom down lever is operated, the pressure of hydraulic oil introduced into the inside through the port of the variable drain check valve increases the elastic force of the built-in coil spring, thereby increasing the back pressure. It includes a variable drain check valve so that it can be, and is characterized in that the flow rate of the pump is reduced by a negative hydraulic signal according to the back pressure increase of the variable drain check valve.

In addition, according to a preferred embodiment of the present invention, the spool controlled by the operation of the lever, the drain line installed so that the hydraulic oil discharged from the boom cylinder is discharged to the drain tank through the spool and provided with a variable drain check valve, and the lever In neutral, it further includes a neutral flow path provided so that hydraulic oil supplied from the pump is supplied to a drain line upstream of the variable drain check valve through the spool, and a negative hydraulic signal according to the pressure applied to the negative orifice installed in the neutral flow path is transmitted to the pump. is input to the regulator that controls the flow rate of the pump.

In addition, according to a preferred embodiment of the present invention, hydraulic fluid is introduced or discharged into the variable drain check valve by a lever pressure signal controlling the spool.

In addition, according to a preferred embodiment of the present invention, the variable drain check valve includes a housing having an inlet to which a drain line is connected and an outlet through which hydraulic oil introduced through the drain line is discharged, and a piston located inside the housing to open and close the inlet. And, a spring sheet whose edge is inserted into the guide passage formed on the inner surface of the housing in the longitudinal direction of the housing, a coil spring whose both ends are in contact with one surface of the piston and the spring seat, and a spring sheet formed on the edge of the other surface and located in the guide passage and a port formed at the rear end of the housing and having a flow path communicating with the guide passage.

Further, according to a preferred embodiment of the present invention, a piston rod extending from the piston toward the outlet is further included, and both ends of the coil spring are in contact with the piston and the spring seat while surrounding the piston rod.

In addition, according to a preferred embodiment of the present invention, when the boom down lever is operated, hydraulic oil flows into the guide passage through the port by the lever pressure signal, so that the spring elasticity of the variable drain check valve increases, and the neutral and boom up levers are operated When the hydraulic fluid in the guide passage flows out through the port, the spring elasticity of the variable drain check valve decreases.

As described above, in the prior art, when the boom of an excavator descends, hydraulic oil is supplied to the cylinder, so energy is wasted. However, the construction machine for reducing energy during the boom-down operation according to the present invention It has the advantage of saving energy by blocking the supply of unnecessary flow from the pump by improving the back pressure of the drain check valve.

In addition, in the jack-up operation of lifting the excavator body while the boom is descending, even if the cylinder speed decreases and the elastic force of the coil spring of the variable drain check valve increases, the increase in back pressure is limited, so that the intended flow rate of the pump is supplied and the jack-up operation can be performed smoothly. There are advantages to being able to.

1 is a conceptual diagram of a hydraulic circuit when an RCV lever for operating a boom cylinder of an excavator according to the prior art is in a neutral position;
2 is a conceptual diagram of a hydraulic circuit when the boom is in an up state;
3 is a conceptual diagram of a hydraulic circuit when the boom is in a down state.
4 is a conceptual diagram showing a variable drain check valve according to the present invention;
FIG. 5 is a conceptual diagram illustrating a state in which the chamber of the variable drain check valve shown in FIG. 4 is infused with working oil to increase spring elasticity.
6 is a conceptual diagram of a hydraulic circuit when an RCV lever operating a boom cylinder of an excavator equipped with a variable drain check valve shown in FIG. 4 is in a neutral position;
7 is a conceptual diagram of a hydraulic circuit when the excavator shown in FIG. 6 is in a boom-up state;
8 is a conceptual diagram of a hydraulic circuit when the excavator shown in FIG. 6 is in a boom-down state.

Hereinafter, a preferred embodiment of a construction machine for energy reduction during boom down operation according to the present invention will be described in detail with reference to the accompanying drawings.

In the drawings, FIG. 4 is a conceptual diagram showing a variable drain check valve according to the present invention, and FIG. 5 is a conceptual diagram showing a state in which hydraulic oil is introduced into the chamber of the variable drain check valve shown in FIG. 4 to increase spring elasticity. 6 is a conceptual diagram of the hydraulic circuit when the RCV lever for manipulating the boom cylinder of the excavator equipped with the variable drain check valve shown in FIG. 4 is in a neutral position, and FIG. 7 is the excavator shown in FIG. 6 in a boom-up state 8 is a conceptual diagram of the hydraulic circuit when the excavator shown in FIG. 6 is in a boom-down state.

As shown in FIGS. 4 and 5, the variable drain check valve 100 includes a housing 110 having an inlet 111 through which hydraulic oil flows in at the front end and an outlet 112 through which hydraulic oil flows out at the rear end of the housing 110, A piston 113 that opens and closes the inlet 111 inside the housing 110, a piston rod 114 extending from the piston 113 to the rear end, and the piston rod 114 penetrate the center and the edge is the housing 110 ) The spring seat 118 located in the guide passage 116 formed in the longitudinal direction of the housing 110 on the inner surface, and both ends on one side of the piston 113 and the spring seat 118 surrounding the piston rod 114 The contact coil spring 119, the sealing portion 121 formed on the edge of the other surface of the spring seat 118 and located in the guide passage 116, and formed at the rear end of the housing 110 and communicating with the guide passage 116 It includes a port 123 in which a flow path is formed.

In the excavator configured as described above, when hydraulic oil flows in through the port 123 as shown in FIG. 100) moves to the tip where the inlet 111 is formed. At this time, although not shown in the drawings, a sealing member is mounted around the sealing part 121 to seal the gap between the guide passage 116 and the sealing part 121 so that the hydraulic oil introduced into the guide passage 116 is inside the housing 110. prevent spillage into

Therefore, when the hydraulic fluid flows into the port 123, the sealing part 121 and the spring seat 118 move to the front end, and the spring seat 118 moves to the front end of the piston 113 (a state in which the inlet is closed). As the coil spring 119 is compressed as it moves forward, the spring elasticity of the variable drain check valve 100 increases.

Conversely, when the hydraulic oil flows out through the port 123 of the variable drain check valve 100, the spring seat 118 moves backward by the elasticity of the coil spring 119, that is, to the rear of the guide passage 116, and the variable drain The spring elasticity of the check valve 100 is reduced.

As described above, in the variable drain check valve 100 according to the present invention, when hydraulic oil is introduced through the port 123 formed in the housing 110, the spring elasticity of the variable drain check valve 100 increases, and the hydraulic oil moves through the port 123. ), the spring elasticity of the variable drain check valve 100 decreases.

Below, in a state where the variable drain check valve 100 configured as described above is applied to the hydraulic circuit of an excavator, the operation of the variable drain check valve 100 according to the neutral state, boom up, boom down, and jack-up operations and the control of the flow rate of the pump explain about

As shown in FIG. 6, when the RCV lever 1 is placed in a neutral state, the RCV pressure is not applied to the spool 3, so the spool 3 is fixed in the middle position as shown in FIG.

In this case, the hydraulic oil supplied by the operation of the pump 5 proceeds to the negative orifice 21 along the neutral flow path of the spool 3. When a large flow rate passes through the negative orifice 21, a negative pressure signal 21S is generated. will rise

When the negative pressure signal 21S rises, the pump regulator 23 reduces the flow rate of the pump 5 by the increased negative pressure signal 21S, and the variable drain check valve mounted on the downstream side of the negative orifice 21 In (100), back pressure is formed by hydraulic oil.

On the other hand, in the neutral state, hydraulic oil does not flow into the port 123 of the variable drain check valve 100, so the spring seat 118 is in a state of maximum retraction, and the coil spring 119 also includes the piston 113 and the spring seat 118. ) is located in the most extended state between

In this state, as shown in FIG. 7, when the operator positions the RCV lever 1 in the boom-up operation for the boom-up operation, the RCV pressure presses one side of the spool 3 accordingly, and the spool 3 It moves proportionally according to the RCV pressure signal.

In the case of an RCV pressure signal of about 50%, some of the neutral passages are open, and the flow rate of the pump (5) opens the check valve (31) and passes through the passage of the spool (3) and flows into the rear chamber (11B) of the cylinder (10). The stroke of the cylinder 10 is extended so that the boom rises.

On the other hand, according to the extension of the stroke of the cylinder 10, the hydraulic oil of the front chamber 11F of the cylinder 10 flows out, and the hydraulic oil that flows out is drained through the flow path of the spool 3 and drained through the variable drain check valve 100. flows into the tank

At this time, as the hydraulic fluid flowing out through some of the neutral passages flows into the negative orifice 21, the negative pressure signal 21S formed lower than the negative pressure signal at the neutral position described above is input to the pump regulator 23 and the pump 5 ), the discharge flow rate is determined.

Therefore, in the drain check valve 100, the fluid through the neutral flow path of the spool 3 and the fluid discharged from the front chamber 11F of the cylinder 10 combine and flow, but the hydraulic oil flows through the port 123 of the variable drain check valve 100. does not flow in, so the spring elastic force is small and the formed back pressure is small, so the negative pressure signal (21S) has a small effect, and the effect on the discharge flow rate of the pump (5) is also small.

On the other hand, when the boom is down by operating the RCV lever 1 in a neutral state, as shown in FIG. 8, the RCV pressure is applied to the other side of the spool 3, and the position of the spool 3 is the RCV pressure It moves proportionally according to the signal.

In the case of an RCV pressure signal of about 50%, some of the neutral passages are open, and the flow rate of the pump (5) opens the check valve (31) and flows into the front chamber (11F) of the cylinder (10) through the passage of the spool (3). The stroke of the cylinder 10 is contracted so that the boom descends.

At this time, in the case of the boom cylinder 10, it is accelerated by the energy according to its own weight and accelerates more than the acceleration by the flow rate supplied from the pump 5, and accordingly, in the rear chamber 11B of the cylinder 10, the spool 3 with a large flow rate ) and flows into the drain tank 13 through the variable drain check valve 100.

When the operator operates the RCV lever (1) in the boom-down mode, working oil flows into the port 123 of the variable drain check valve 100 by the boom-down RCV pressure, and as described above, the working oil flows into the port 123 As this happens, the spring seat 118 moves forward and compresses the coil spring 119. In this way, as the coil spring 119 is compressed and the elasticity increases, the back pressure for the same flow rate increases.

When the boom is down, as the back pressure of the variable drain check valve 100 increases, the back pressure of the negative orifice 21 also rises, and the pressure signal 21S of the regulator 23 also rises, resulting in the discharge flow rate of the pump 5 this decreases

As such, there is an advantage in that energy can be saved by reducing the discharge flow rate of the unnecessary pump 5 when the boom of the excavator having the negative hydraulic system is down.

On the other hand, during the jack-up operation, since the self-weight energy of the boom cylinder 10 is dissipated, the speed of the boom cylinder is lowered compared to when it comes down in the air (the boom-down state in which energy due to its own weight is applied).

Therefore, even if the elastic force of the coil spring 119 of the variable drain check valve 100 increases as the flow rate of the rear chamber 11B of the cylinder 10 decreases, the increase in back pressure is limited.

As such, during the jack-up operation, as the increase in back pressure of the variable drain check valve 100 is limited, the negative pressure signal 21S forms a lower pressure than when the boom is down, and accordingly, the discharge flow rate of the pump 5 increases It is more than when it is down, so it can perform jack-up operation smoothly.

1 : RCV lever
3 : Spool
5 : Pump
10: Cylinder
11F: front room
11B: rear room
13: drain tank
14: drain line
21: negative orifice
21S: negative input signal
23: regulator
31: check valve
100: variable drain check valve
110: housing
111: inlet
112: outlet
113: piston
114: piston rod
116: guide passage
118: spring seat
119: coil spring
121: seal
123: port

Claims (6)

It includes a variable drain check valve in which back pressure is increased by increasing the elasticity of the built-in coil spring when the boom down lever is operated.
A construction machine for reducing energy during a boom-down operation, characterized in that the flow rate of the pump is reduced by a negative hydraulic signal according to the increase in back pressure of the variable drain check valve.
According to claim 1,
A spool controlled by operation of a lever;
A drain line installed so that hydraulic fluid discharged from the boom cylinder is discharged to a drain tank through a spool and equipped with a variable drain check valve;
Further comprising a neutral flow path provided so that the hydraulic oil supplied from the pump when the lever is neutral is supplied to the drain line upstream of the variable drain check valve through the spool,
A construction machine for energy reduction during a boom-down operation, characterized in that a negative hydraulic signal according to the pressure applied to the negative orifice installed in the neutral flow path is input to a regulator that controls the pump to control the flow rate of the pump.
According to claim 2,
A construction machine for energy reduction during a boom-down operation, characterized in that hydraulic fluid flows in or out of the variable drain check valve by a lever pressure signal that controls the spool.
According to claim 3,
The variable drain check valve,
A housing having an inlet to which a drain line is connected and an outlet through which the hydraulic oil introduced through the drain line is discharged;
A piston located inside the housing and opening and closing the inlet;
A spring seat whose edge is inserted into the guide passage formed in the longitudinal direction of the housing on the inner surface of the housing;
A coil spring in which both ends are in contact with one surface of the piston and the spring seat;
A sealing part formed on the edge of the other surface of the spring seat and located in the guide passage;
A construction machine for energy reduction during a boom-down operation, characterized in that it includes a port formed at the rear end of the housing and having a passage formed in communication with the guide passage.
According to claim 4,
Further comprising a piston rod extending from the piston toward the outlet,
The coil spring is a construction machine for energy reduction during a boom-down operation, characterized in that both ends are in contact with the piston and the spring seat while wrapping the piston rod.
According to claim 4,
When the boom down lever is operated, hydraulic oil flows in through the port by the lever pressure signal, increasing the spring elasticity of the variable drain check valve, and when the neutral and boom up levers are operated, hydraulic oil flows out through the port and Construction machinery for energy reduction during boom down operation, characterized in that the elasticity is reduced.

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