JP2011052718A - Hydraulic circuit for working machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently recover and recycle energy of an operating fluid with simple configuration regarding a hydraulic circuit for a working machine. <P>SOLUTION: The hydraulic circuit is provided with: a hydraulic cylinder 1 having a first oil chamber 1a and a second oil chamber 1b; and a hydraulic pump 2 which is a hydraulic supply source to the hydraulic cylinder 1. A recycling line L3 is formed branching off from a hydraulic supply line L1 connecting the first oil chamber 1a to the hydraulic pump 2. The recycling line L3 is provided with a motor recycling control means 4 allowing the flow of the operating fluid discharged from the first oil chamber 1a, and a recycling hydraulic motor 5 rotationally driven while receiving the supply of the operating fluid. The rotational driving force of the recycling hydraulic motor 5 is transmitted to the hydraulic pump 2 through a rotational driving force transmission means 6 to assist the rotational driving force of the hydraulic pump 2. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a hydraulic circuit related to driving of a hydraulic cylinder provided in a work machine.

  Conventionally, in a work machine represented by a hydraulic excavator or a crane vehicle, various techniques for regenerating and utilizing the energy of hydraulic oil discharged to the hydraulic oil tank in accordance with the expansion and contraction operation of the hydraulic actuator have been proposed. For example, as shown in Patent Document 1, there is a technique in which excess pressure fluid supplied to a swing motor is accumulated in an accumulator, and this pressure fluid is supplied to a suction port of a hydraulic pump and reused for driving a hydraulic actuator. Are known. In this technique, the energy of hydraulic oil is stored in the accumulator as hydraulic energy.

  In addition, as shown in Patent Document 2, a technique is also known in which a motor / generator is rotationally driven by high-pressure hydraulic oil discharged from a hydraulic cylinder to generate electric power, and the electric power is stored in a battery device. In other words, this technique stores the energy of hydraulic oil as electric energy in the battery device. In these hydraulic regeneration technologies, it is said that energy loss can be reduced by storing the energy of hydraulic oil in some form.

JP 2007-10006 A JP 2006-336847 A

  However, the conventional hydraulic regeneration technology requires a hydraulic accumulator and battery device to temporarily store the hydraulic oil energy, as well as various types of hydraulic pumps, generator motors, hydraulic valves, control inverters, etc. Attached equipment is required. For this reason, there is a problem that the cost for establishing the quality as a product rises due to complication of the apparatus configuration and control.

  The present invention has been made in view of such a problem, and provides a hydraulic circuit for a work machine that can efficiently recover and recycle the energy of hydraulic oil with a simple configuration. With the goal.

  To achieve the above object, a hydraulic circuit for a working machine according to a first aspect of the present invention is mounted on the working machine and includes a hydraulic cylinder having a first oil chamber and a second oil chamber therein, A hydraulic pump that is a hydraulic supply source, a regeneration pipe formed by branching from a hydraulic supply passage that connects the first oil chamber of the hydraulic cylinder and the hydraulic pump, and is interposed on the regeneration pipe, A regenerative hydraulic motor that is rotationally driven by the supply of hydraulic oil, and the regeneration of the hydraulic oil that is interposed on the hydraulic cylinder side of the regenerative hydraulic motor on the regeneration pipeline and discharged from the first oil chamber Motor regeneration control means for permitting the flow into the pipeline and blocking the flow of the hydraulic oil supplied from the hydraulic pump to the first oil chamber into the regeneration pipeline, and rotation of the regeneration hydraulic motor Transmits driving force as rotational driving force of the hydraulic pump It is characterized and the rolling driving force transmitting means, further comprising: a.

  According to a second aspect of the present invention, there is provided a hydraulic circuit for a working machine according to the present invention, in addition to the configuration according to the first aspect, wherein the motor regeneration control means includes a poppet that blocks the flow of the hydraulic oil to the regeneration hydraulic motor side. And a pilot control valve that controls the poppet of the pilot check valve to open the regeneration pipe during the reduction operation on the first oil chamber side in the hydraulic cylinder. Yes.

  According to a third aspect of the present invention, there is provided a hydraulic circuit for a work machine according to the present invention, in addition to the configuration according to the first or second aspect, an engine for driving a rotary shaft of the hydraulic pump, and a rotational drive between the hydraulic pump and the engine. A gear box interposed on the force transmission path, wherein the rotational driving force transmission means is built in the gear box and connected to the output shaft of the engine and the rotation shaft of the hydraulic pump. It is characterized by having one gear and a second gear meshed with the first gear and built in the gear box and connected to the rotating shaft of the regenerative hydraulic motor.

According to a fourth aspect of the present invention, there is provided a hydraulic circuit for a working machine according to the present invention, in addition to the configuration of the third aspect, a pilot pump connected to the output shaft of the engine and a pilot hydraulic fluid discharged from the pilot pump And a lubricating oil supply path for introducing the regenerated hydraulic motor into the regenerated hydraulic motor.
Further, the hydraulic circuit of the working machine according to the fifth aspect of the present invention has the configuration according to any one of the first to fourth aspects, more than the branch point with the regeneration pipe line on the hydraulic pressure supply path. It is characterized by further comprising a check valve interposed on the hydraulic pump side and blocking the flow of the hydraulic oil discharged from the first oil chamber to the hydraulic pump side.

  A hydraulic circuit for a work machine according to a sixth aspect of the present invention has the above-described configuration according to any one of the first to fourth aspects, in addition to the branch point with the regeneration pipeline on the hydraulic pressure supply path. A second regeneration conduit that is further branched from the hydraulic pump side and that supplies part of the hydraulic oil discharged from the first oil chamber to the second oil chamber, and is disposed on the second regeneration conduit. And a flow rate control valve for controlling the flow rate of the working oil flowing through the second regeneration pipe according to the flow rate of the working oil discharged from the first oil chamber.

  According to the hydraulic circuit of the working machine of the working machine of the present invention (Claim 1), the energy of the hydraulic oil discharged from the first oil chamber of the hydraulic cylinder is used as mechanical energy (that is, the rotational driving force of the regenerative hydraulic motor). By transmitting to the hydraulic pump, energy can be efficiently recovered as compared with a regeneration method using a battery or an accumulator. Further, there is no need to temporarily store energy unlike a battery or an accumulator, and the cost can be reduced with a simple configuration.

Further, according to the hydraulic circuit of the working machine of the present invention (Claim 2), the hydraulic oil discharged from the first oil chamber side of the hydraulic cylinder can be introduced into the regeneration line with a simple configuration. The energy of hydraulic oil can be reused as mechanical energy (rotational driving force).
Moreover, according to the hydraulic circuit of the working machine of the present invention (Claim 3), the rotational driving force of the regenerative hydraulic motor can be transmitted to the hydraulic pump with a simple configuration. The transmission loss of the rotational driving force is about the loss related to the volumetric efficiency of the regenerative hydraulic motor and the transmission efficiency of the gear box, and the rotational driving force can be transmitted efficiently. In addition, when the hydraulic oil is not flowing through the regeneration pipeline, the regeneration hydraulic motor idles without load, so that energy loss can be suppressed.

  Moreover, according to the hydraulic circuit of the working machine of the present invention (Claim 4), the regenerative hydraulic motor can be lubricated with a simple configuration. Note that the regenerative hydraulic motor in a state where it is rotationally driven by the supply of hydraulic oil discharged from the hydraulic cylinder does not require lubricating oil. In other words, since the regenerative hydraulic motor requires lubricating oil only during idling in a no-load state, it is not necessary to increase the capacity of the pilot pump (pilot hydraulic oil supply capacity), and the cost can be reduced. .

Further, according to the hydraulic circuit of the working machine of the present invention (Claim 5), all the hydraulic oil discharged from the hydraulic cylinder can be introduced to the regeneration pipeline side, and the recycling efficiency can be further improved.
According to the hydraulic circuit of the working machine of the present invention (Claim 6), the hydraulic cylinder is extended by supplying a part of the hydraulic oil discharged from the first oil chamber of the hydraulic cylinder to the second oil chamber. Speed can be controlled and operability can be improved.

1 is a schematic perspective view showing a hydraulic excavator to which a hydraulic circuit of a work machine according to an embodiment of the present invention is applied. It is a hydraulic circuit diagram which shows the whole structure of this hydraulic circuit. It is a hydraulic circuit diagram which shows the hydraulic circuit of the working machine as a modification of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[1. Excavator configuration]
The present invention is applied to a hydraulic excavator 30 shown in FIG. The hydraulic excavator 30 includes a lower traveling body 31 equipped with a crawler traveling device, and an upper swing body 32 mounted on the lower traveling body 31. The upper turning body 32 is installed on the lower traveling body 31 via a turning device so as to be turnable in the horizontal direction.

A cab 33 on which an operator (operator) rides is provided on the vehicle front side of the upper swing body 32, and a front work device 34 provided adjacent to the cab 33 so as to extend forward of the vehicle. A counterweight 35 is provided at the rearmost end of the upper swing body 32 to maintain the weight balance of the machine body.
The front working device 34 includes three members, a boom 34A, a stick 34B, and a bucket 34C, each of which operates independently. The boom 34 </ b> A is supported so as to be swingable in the undulation direction (the longitudinal direction of the machine body) with respect to the upper swing body 32. The stick 34B is supported so as to be swingable in the front-rear direction of the fuselage with respect to the tip of the boom 34A, and the bucket 34C is supported so as to be swingable in the front-rear direction with respect to the tip of the stick 34B. Each of the boom 34A, the stick 34B, and the bucket 34C is provided with a hydraulic cylinder, and swings according to the expansion / contraction operation of each hydraulic cylinder.

  Each of the stick 34B and the bucket 34C is driven by a single hydraulic cylinder (stick cylinder 37, bucket cylinder 38). On the other hand, the boom 34A is driven by two boom cylinders 1 and 1 (hydraulic cylinders). The tip ends of the boom cylinders 1 and 1 are pivotally supported by the upper swing body 32, and the tip ends of the rods are pivotally supported by the boom 34A. The operating amounts of the boom cylinders 1 and 1 are the same, and are simply referred to as the boom cylinder 1 hereinafter.

  An engine room 36 in which an engine 7 that is a drive source of the hydraulic excavator 30 is installed is provided in front of the counterweight 35. In addition, a boom operation lever 21 for an operator to operate the boom 34A is provided in the cab 33 of the excavator 30. The boom operation lever 21 is a pilot hydraulic remote control lever and generates a pilot pressure corresponding to the tilting direction. This pilot pressure is used to control the flow rate and flow direction of the hydraulic oil supplied to the boom cylinder 1.

[2. Configuration of hydraulic circuit]
FIG. 2 shows a hydraulic circuit related to the driving of the boom cylinder 1. The hydraulic circuit includes a main drive circuit 10A, a regeneration circuit 10B, and a pilot pressure generation circuit 20. In FIG. 2, the reproduction circuit 10B is surrounded by a one-dot chain line.
[2-1. Pilot pressure generation circuit 20]
The pilot pressure generation circuit 20 is a circuit for outputting a pilot pressure corresponding to an input operation to the boom operation lever 21. As shown in FIG. 2, a remote control valve 22 is fixed to the lower end portion of the boom operation lever 21. The remote control valve 22 is a control valve that generates a pilot pressure having a magnitude corresponding to the operation amount and the operation direction input to the boom operation lever 21. A pilot pump 11 and a hydraulic oil tank 9 are connected to the remote control valve 22.

A pair of pressure reducing valves 23U, 23D is built in the remote control valve 22, and the upper ends of these pressure reducing valves 23U, 23D are connected to the lower end of the boom operation lever 21. One of the pair of pressure reducing valves 23U and 23D corresponding to the tilting direction of the boom operating lever 21 is opened according to the tilting angle, and a pilot pressure corresponding to the opening is generated.
A symbol U in FIG. 2 indicates a pilot pressure generated when operating in the direction in which the boom cylinder 1 is extended (boom raising direction), and a symbol D indicates a pilot generated when operating in the direction in which the boom cylinder 1 is contracted (boom lowering direction). Indicates pressure. These pilot pressures U and D are transmitted to a main drive circuit 10A and a regeneration circuit 10B, which will be described below, and are used in the control of the present invention as pilot pressures U and D at the same symbols in each place in FIG. The

[2-2. Main drive circuit 10A]
The main drive circuit 10A is a hydraulic circuit that connects the boom cylinder 1 and the main pump 2 (hydraulic pump) to form a hydraulic oil flow path. The main pump 2 is a variable displacement hydraulic pump driven by the engine 7, and sucks hydraulic oil from the hydraulic oil tank 9 and supplies it to the boom cylinder 1. The main pump 2 is also a hydraulic drive source for a turning device (not shown) and the front work device 34. The output shaft 7 a of the engine 7 is connected to the rotating shaft 2 a of the main pump 2 via the gear box 6.

  In the cylinder of the boom cylinder 1, a head chamber 1a (first oil chamber) and a rod chamber 1b (second oil chamber) are formed. The head chamber 1 a is an oil chamber to which hydraulic oil is supplied when the boom cylinder 1 is extended, and the rod chamber 1 b is a hydraulic pressure to which hydraulic oil is supplied when the boom cylinder 1 is contracted. The head chamber 1a is disposed below the rod chamber 1b and receives a load due to the weight of the front working device 34 input from the rod. Therefore, substantially larger pressure is applied to the head chamber 1a of the boom cylinder 1 than to the rod chamber 1b.

  Between the main pump 2 and the boom cylinder 1, a control valve 8 for controlling the flow rate of hydraulic oil supplied to the boom cylinder 1 and the supply direction is interposed. Hereinafter, the pipe connecting the control valve 8 and the head chamber 1a of the boom cylinder 1 is referred to as a first pipe L1, and the pipe connecting the control valve 8 and the rod chamber 1b of the boom cylinder 1 is the second pipe. Called L2.

The control valve 8 is configured as a pilot-type flow rate control valve that variably controls the flow rate and flow direction of the hydraulic oil by switching the spool position to a plurality of positions. Pilot pipe lines for introducing pilot pressures U and D generated by the pilot pressure generation circuit 20 are connected to both ends of the spool of the control valve 8.
For example, when the pilot pressure U is introduced into the control valve 8, the spool moves to the U position, and a circuit is formed in which the hydraulic oil discharged from the main pump 2 is supplied to the first pipeline L1 side. Thereby, the boom cylinder 1 operates in the extending direction. Further, when the pilot pressure D is introduced, the spool moves to the D position, and a circuit is formed in which hydraulic oil from the main pump 2 is supplied to the second pipeline L2 side. Thereby, the boom cylinder 1 operates in the reduction direction. When neither of these pilot pressures U and D is introduced, the spool is held at the X position, and the supply of hydraulic oil to the boom cylinder 1 is stopped.

A check valve 12 is interposed on the first pipeline L1. This check valve 12 is a one-way valve that permits the flow of hydraulic oil from the control valve 8 side to the head chamber 1a side and blocks the flow of hydraulic oil in the reverse direction.
A pilot pump 11 is connected in series with the rotating shaft 2 a of the main pump 2. The hydraulic oil discharged from the pilot pump 11 is supplied to the pilot pressure generation circuit 20 and is supplied as a lubricating oil to the regenerative hydraulic motor 5 described later. A flow path of the hydraulic oil supplied from the pilot pump 11 to the regenerative hydraulic motor 5 is referred to as a lubricating oil supply path L7. The supply of hydraulic oil through the lubricating oil supply path L7 is always performed.

  The hydraulic oil actually acts as lubricating oil when the regenerative hydraulic motor 5 is idling. Therefore, a control valve may be provided that opens the lubricating oil supply path L7 only when the regenerative hydraulic motor 5 is idling without load, and closes the lubricating oil supply path L7 at other times.

[2-3. Reproduction circuit 10B]
From the head chamber 1a side of the check valve 12 on the first pipeline L1, a regeneration pipeline L3 is branched and formed. A branch point between the first pipeline L1 and the regeneration pipeline L3 is shown as a branch point Q in FIG. The regeneration conduit L3 is a conduit for introducing the hydraulic oil discharged from the head chamber 1a to the regeneration hydraulic motor 5 side.

The regeneration hydraulic motor 5 is a hydraulic motor interposed in the regeneration conduit L3, receives the supply of hydraulic oil, rotationally drives the rotary shaft 5a, and discharges the hydraulic oil to the hydraulic oil tank 9. That is, the regeneration hydraulic motor 5 converts the energy of the hydraulic oil flowing through the regeneration conduit L3 into the energy of the rotational motion of the rotating shaft 5a.
Between the regeneration hydraulic motor 5 and the branch point Q on the regeneration line L3, a motor regeneration control valve 4 (motor regeneration control means) is interposed. The motor regeneration control valve 4 has a function of allowing the operating oil discharged from the head chamber 1a to flow into the regeneration conduit L3, and the regeneration of the operating oil supplied from the main pump 2 to the head chamber 1a of the boom cylinder 1. This is a control valve unit having a function of blocking the flow into the pipe L3. The motor regeneration control valve 4 includes a pilot check valve 4a and a pilot control valve 4c.

The pilot check valve 4a is a check valve that changes the operation of the poppet 4b by pilot control. The interior of the pilot check valve 4a is partitioned into a chamber A, a chamber B, and a chamber C by a poppet 4b.
The chamber A is connected with a pipeline connected to the branch point Q side and a pilot pipeline L5 connected to the pilot control valve 4c. The pressure in the chamber A is introduced into the pilot line L5. The pilot line L4 is connected to the chamber B, and the pressure in the chamber B varies in response to the pressure introduced from the pilot line L4. The chamber C is connected to a pipe line connected to the regeneration hydraulic motor 5 side. The chamber B has a built-in spring that biases the poppet 4b in the directions of the chambers A and C.

The pilot check valve 4a functions as a normal one-way valve when the pressure in the chamber B is the same as the pressure in the chamber A. That is, the pilot check valve 4a permits the flow of hydraulic oil from the regeneration hydraulic motor 5 side to the branch point Q side, and blocks the flow of hydraulic oil from the branch point Q side to the regeneration hydraulic motor 5 side.
On the other hand, when the pressure in the chamber B is lower than the pressure in the chamber A, the poppet 4b is pushed back from the chamber A side to the chamber B side, and is fixed with the flow path from the chamber A to the chamber C open. . That is, in this case, the pilot check valve 4a permits the flow of hydraulic oil from the branch point Q side to the regenerated hydraulic motor 5 side and the flow of hydraulic oil in the reverse direction.

The pilot control valve 4c is a two-position switching valve that switches the position of the spool in accordance with the pilot pressure D introduced from the pilot pressure generation circuit 20, and has a function of changing the pressure in the pilot line L4. A pilot line for introducing a pilot pressure D is connected to one end of the spool of the pilot control valve 4c.
For example, when the pilot pressure D is introduced into the pilot control valve 4c, the spool moves to the D position to form a flow path that closes the pilot line L5 and opens the pilot line L4 to the hydraulic oil tank 9. . That is, a state is formed in which the chamber A has a higher pressure than the chamber B in the pilot check valve 4a. On the other hand, when the pilot pressure D is not introduced into the pilot control valve 4c, the spool moves to the X position and forms a flow path that connects the pilot lines L4 and L5. That is, the pilot check valve 4a forms a state where the chamber A and the chamber B have the same pressure.

Therefore, when the pilot pressure D is introduced to the pilot control valve 4 c, the hydraulic oil is allowed to flow from the branch point Q side to the regeneration hydraulic motor 5 side, and the hydraulic oil is introduced into the regeneration hydraulic motor 5.
From between the motor regeneration control valve 4 and the regeneration hydraulic motor 5 on the regeneration line L3, a relief line L6 for branching the working oil to the working oil tank 9 is branched and formed. Further, the relief line L6 A relief valve 13 is interposed above. The relief valve 13 sets an upper limit value of the hydraulic pressure in the regeneration pipeline L5, and releases the hydraulic fluid to the hydraulic oil tank 9 when the pressure in the regeneration pipeline L3 becomes excessively high. To function.

A rotation shaft 5a of the regenerative hydraulic motor 5 is connected to a gear box 6 (rotational driving force transmission means). The gear box 6 is a gear mechanism having a function of transmitting the rotational driving force of the regenerative hydraulic motor 5 to the main pump 2 and the engine 7. As shown in FIG. 2, a first gear 6 a and a second gear 6 b and a third gear 6 c that mesh with the first gear 6 a are built in the gear box 6.
The first gear 6 a is a gear connected to the output shaft 7 a of the engine 7 and the rotation shaft 2 a of the main pump 2, and rotates in synchronization with the rotation speed of the engine 7 and the rotation speed of the main pump 2. It should be noted that a speed change mechanism may be interposed between the first gear 6a and the output shaft 7a of the engine 7 or the rotary shaft 2a of the main pump 2 to change the rotational speed, but the description is simplified in FIG. Is shown.

  Similarly, the second gear 6 b is a gear connected to the rotation shaft 5 a of the regenerative hydraulic motor 5 and rotates in synchronization with the rotation speed of the regenerative hydraulic motor 5. The third gear 6 c is a gear connected to the rotating shaft 14 a of the generator / motor 14. The first gear 6a and the second gear 6b rotate synchronously at a predetermined speed ratio. A clutch device 15 is interposed between the first gear 6a and the third gear 6c, and the engagement of these gears can be connected and disconnected as necessary.

The generator motor 14 is a generator for converting the energy of the rotational motion of the third gear 6c into electric energy. The electric power generated here is stored in a battery device (not shown).
[3. Action]
[3-1. During boom raising operation]
When the boom operation lever 21 is operated in the boom raising direction, the pressure reducing valve 23U is opened according to the tilt angle, and the pilot pressure U is output from the remote control valve 22 in the pilot pressure generating circuit 20. When the pilot pressure U is introduced into the control valve 8 of the main drive circuit 10A, the spool is set to the U position. As a result, the hydraulic oil discharged from the main pump 2 passes through the first pipe L1, passes through the check valve 12, and is supplied to the head chamber 1a side of the boom cylinder 1. Therefore, the boom cylinder 1 operates in the extending direction, and the hydraulic oil is discharged from the rod chamber 1b side. The discharged hydraulic oil passes through the second pipe L2 and returns to the hydraulic oil tank 9 via the control valve 8.

  At this time, since the pilot pressure D is not introduced into the pilot control valve 4c, the spool is set to the X position. As a result, the pilot lines L4 and L5 connected to the pilot check valve 4a are in communication with each other, and the hydraulic pressure of the hydraulic oil that is about to flow into the regeneration line L3 from the branch point Q is changed to the chamber A and the pilot check valve 4a. It is introduced into both chambers B. Therefore, the poppet 4b of the pilot check valve 4a maintains the closed state of the chamber C, and hydraulic oil does not flow to the regeneration hydraulic motor 5 side.

  The rotational driving force transmitted from the engine 7 to the main pump 2 is also transmitted to the first gear 6a and the second gear 6b, and the regenerative hydraulic motor 5 is driven by the driving force of the engine 7. Further, the hydraulic oil discharged from the pilot pump 11 is supplied to the regenerative hydraulic motor 5 as lubricating oil. On the other hand, at this time, since the hydraulic oil does not flow through the regeneration pipe L3, the regeneration hydraulic motor 5 rotates idly in a no-load state. Therefore, there is almost no energy loss associated with driving the regenerative hydraulic motor 5.

[3-2. During boom lowering operation]
When the boom operation lever 21 is operated in the boom lowering direction, the pressure reducing valve 23D is opened according to the tilt angle, and the pilot pressure D is output from the remote control valve 22 in the pilot pressure generating circuit 20. When the pilot pressure D is introduced into the control valve 8 of the main drive circuit 10A, the spool is set to the D position. As a result, the hydraulic oil discharged from the main pump 2 passes through the second pipe L2 and is supplied to the rod chamber 1b side of the boom cylinder 1. Accordingly, the boom cylinder 1 operates in the reduction direction, and hydraulic oil is discharged from the head chamber 1a side.

  Since the weight of the front working device 34 acts on the head chamber 1a of the boom cylinder 1, when the front working device 34 is not grounded, the pressure of the hydraulic oil discharged from the head chamber 1a Becomes higher than the pressure of the hydraulic oil on the rod chamber 1b side. In addition, since the check valve 12 is interposed on the first pipeline L1, the high-pressure hydraulic oil discharged from the head chamber 1a flows from the branch point Q to the regeneration pipeline L3 side.

  At this time, since the pilot pressure D is introduced to the pilot control valve 4c, the spool is set to the D position. That is, the connected pilot pipelines L4 and L5 are shut off, and the pilot pipeline L4 is opened to the hydraulic oil tank 9 and depressurized. As a result, when the hydraulic pressure of the hydraulic oil that is about to flow into the regeneration pipe L3 from the branch point Q is introduced into the chamber A of the pilot check valve 4a, the poppet 4b is pushed back to the chamber B side. Accordingly, the regeneration line L3 on the chamber C side is opened, and high-pressure hydraulic oil flows to the regeneration hydraulic motor 5 side.

The regenerative hydraulic motor 5 is rotationally driven by high-pressure hydraulic oil, and the rotational driving force of the rotational shaft 5a is transmitted from the second gear 6b of the gear box 6 to the first gear 6a, and further to the main pump 2 and the engine 7. The At this time, the hydraulic oil flowing through the regeneration pipe L3 also acts as lubricating oil for the regeneration hydraulic motor 5.
When the clutch device 15 in the gear box 6 is released and the engagement of the first gear 6a and the third gear 6c is released, all of the rotational driving force transmitted from the second gear 6b side is the main pump. 2 and the engine 7 and immediately recycled. On the other hand, when the clutch device 15 is connected, the third gear 6c and the generator motor 14 are driven by the rotational driving force transmitted from the second gear 6b side, and a part of the rotational driving force is converted into electric energy, Electric power is stored in a battery device (not shown). The amount of energy stored here is a value corresponding to the degree of engagement between the first gear 6a and the third gear 6c in the clutch device 15, the gear ratio thereof, the power generation characteristics of the generator / motor 14, and the like.

[4. effect]
Thus, in this hydraulic circuit, the energy of the high-pressure hydraulic oil discharged from the head chamber 1a of the boom cylinder 1 is immediately transmitted to the main pump 2 as mechanical energy (that is, the rotational driving force of the regenerative hydraulic motor 5). Therefore, energy can be efficiently recovered as compared with an energy regeneration method using a battery device or an accumulator. Further, a device for temporarily storing energy like an accumulator can be omitted, and the cost can be reduced with a simple configuration.

Further, in this hydraulic circuit, since the check valve 12 is interposed on the first pipeline L1, all the hydraulic oil discharged from the head chamber 1a of the boom cylinder 1 can be introduced to the regeneration pipeline L3 side. Recycling efficiency can be improved.
Further, in the energy regeneration method of this hydraulic circuit, devices that are frequently used in the hydraulic circuit of a general excavator 30 such as a pilot check valve 4a, a pilot control valve 4b, a regeneration hydraulic motor 5 and a gear box 6 are used. Therefore, an expensive device such as an accumulator and its dedicated valve, a secondary battery, an inverter or the like is unnecessary, and the reliability of the entire hydraulic circuit can be improved while reducing costs.

In particular, when the hydraulic oil discharged from the head chamber 1a of the boom cylinder 1 is recycled, the hydraulic oil can be appropriately supplied with a simple configuration in which the pilot check valve 4a and the pilot control valve are interposed on the regeneration pipe L3. Distribution can be controlled and the energy can be reused as mechanical energy (rotational driving force).
In addition, a configuration for transmitting mechanical energy generated by the regenerative hydraulic motor 5 to the main pump 2 side can also be realized with a simple configuration using the gear box 6. In addition, since the transmission loss of the rotational driving force occurs only to the extent related to the volumetric efficiency of the regenerative hydraulic motor 5 and the transmission efficiency of the gear box 6, the rotational driving force can be transmitted efficiently. Further, when the hydraulic oil is not flowing through the regeneration pipe L3, the regeneration hydraulic motor 5 idles in a no-load state, so that energy loss can be suppressed.

  In addition, the regenerative hydraulic motor 5 that is driven to rotate by receiving the hydraulic oil discharged from the boom cylinder 1 does not need lubricating oil. That is, since the regenerative hydraulic motor 5 requires lubricating oil only during idling in a no-load state, it is not necessary to increase the capacity of the pilot pump 11 (pilot hydraulic oil supply capacity). Cost can be reduced.

  Further, by connecting the clutch device 15 in the gear box 6 during the boom lowering operation, the mechanical energy generated by the regenerative hydraulic motor 5 can be converted into electrical energy by the generator motor 14 and stored. Thereby, not only can the mechanical energy be reused immediately, but it can be reused, for example, to assist the rotational drive of the main pump 2 during the subsequent boom raising operation.

[5. Others]
Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.
In the above-described embodiment, the check valve 12 is interposed on the first pipeline L1, and all the hydraulic oil discharged from the head chamber 1a of the boom cylinder 1 is introduced to the regeneration pipeline L3. Instead of such a configuration, a configuration in which a part of the return oil is supplied to the rod chamber 1b side may be considered.

  For example, as shown in FIG. 3, instead of the check valve 12 in the above-described embodiment, an electromagnetic proportional pilot operation check valve 16 is used, and the first branch line L1 is branched to the second pipeline L2 side. A second regeneration conduit L8 formed in this manner is provided. On the second regeneration pipeline L8, a check valve 17 that allows only the flow of hydraulic fluid from the first pipeline L1 side to the second pipeline L2 side, and hydraulic fluid that circulates to the second pipeline L2 side. And a flow rate control valve 18 for controlling the flow rate. Here, the pilot operation check valve 16 and the flow rate control valve 18 are controlled so that the hydraulic oil flow rate to the second pipe line L2 side becomes a magnitude corresponding to the magnitude of the pilot pressure D.

In this way, by supplying a part of the hydraulic oil discharged from the head chamber 1a of the boom cylinder 1 to the rod chamber 1b, the reduction operation speed of the boom cylinder 1 can be controlled, and the operation of the front working device 34 can be controlled. Can be improved.
Moreover, in the above-mentioned embodiment, although the structure which meshed | engaged the 1st gear 6a and the 2nd gear 6b which were incorporated in the gear box 6 was shown, it shall be the structure which interposes a clutch apparatus between these. It is also possible. In this case, when the regenerative hydraulic motor 5 is idling in a no-load state, the clutch device is disengaged (that is, disengaged), whereby energy loss related to driving of the regenerative hydraulic motor 5 other than during the boom lowering operation. Can be eliminated, and the energy efficiency can be further improved.

  Moreover, in the above-mentioned embodiment, although what applied the hydraulic circuit which concerns on this invention to the hydraulic circuit for driving the boom cylinder 1 of the hydraulic shovel 30 was illustrated, the application object of this invention is not limited to this, For example, the present invention may be applied to the stick cylinder 37 and the bucket cylinder 38. The present invention is suitable for use in recycling of hydraulic oil discharged from an oil chamber in which a self-weight load acts in a hydraulic cylinder. For example, in the stick cylinder 37, return oil from the rod chamber side is used as a regeneration hydraulic motor 5. It is also possible to adopt a circuit configuration to be introduced.

  The present invention can be applied to all working machines such as a hydraulic excavator including a hydraulic cylinder, a hybrid hydraulic excavator, and a crane vehicle amount.

1 Boom cylinder (hydraulic cylinder)
1a Head chamber (first oil chamber)
1b Rod chamber (second oil chamber)
2 Main pump (hydraulic pump)
2a Rotating shaft 4 Motor regeneration control valve (motor regeneration control means)
4a Pilot check valve 4b Poppet 4c Pilot control valve 5 Regenerative hydraulic motor 5a Rotating shaft 6 Gear box (Rotational driving force transmission means)
6a 1st gear 6b 2nd gear 6c 3rd gear 7 Engine 7a Output shaft 8 Control valve 9 Hydraulic oil tank 10A Main drive circuit 10B Regeneration circuit 11 Pilot pump 12 Check valve 13 Relief valve 14 Generator motor 14a Rotating shaft 15 Clutch device 16 Pilot operation check valve 17 Check valve 18 Flow control valve 20 Pilot pressure generation circuit 21 Boom operation lever 22 Remote control valve 23U, 23D Pressure reducing valve 30 Hydraulic excavator L1 First pipe L2 Second pipe L3 Regeneration pipe L4, L5 Pilot Line L6 Relief line L7 Lubricating oil supply line L8 Second regeneration line

Claims (6)

A hydraulic cylinder mounted on a work machine and having a first oil chamber and a second oil chamber inside;
A hydraulic pump that is a hydraulic pressure supply source to the hydraulic cylinder;
A regeneration pipe formed by branching from a hydraulic pressure supply path connecting the first oil chamber of the hydraulic cylinder and the hydraulic pump;
A regenerative hydraulic motor interposed on the regenerative pipe and driven to rotate in response to supply of hydraulic oil;
The hydraulic oil is interposed on the hydraulic cylinder side of the regenerative hydraulic motor on the regenerative pipe, allows the hydraulic oil discharged from the first oil chamber to flow into the regenerative pipe, and from the hydraulic pump Motor regeneration control means for interrupting the flow of hydraulic oil supplied to the first oil chamber into the regeneration pipeline;
A rotational driving force transmitting means for transmitting the rotational driving force of the regenerative hydraulic motor as the rotational driving force of the hydraulic pump;
A hydraulic circuit for a working machine, comprising: The motor regeneration control means
A pilot check valve provided with a poppet for blocking the flow of the hydraulic oil to the regeneration hydraulic motor side;
2. The pilot control valve according to claim 1, further comprising: a pilot control valve that controls the poppet of the pilot check valve to open the regeneration pipe line during a reduction operation on the first oil chamber side in the hydraulic cylinder. Hydraulic circuit of work machine. An engine that drives a rotating shaft of the hydraulic pump;
A gear box interposed on the transmission path of the rotational driving force between the hydraulic pump and the engine,
The rotational driving force transmitting means is
A first gear built in the gear box and connected to the output shaft of the engine and the rotary shaft of the hydraulic pump;
The working machine according to claim 1, further comprising: a second gear that meshes with the first gear and is built in the gear box and connected to a rotating shaft of the regenerative hydraulic motor. Hydraulic circuit. A pilot pump connected to the output shaft of the engine;
The work machine according to claim 3, further comprising a lubricating oil supply path for introducing pilot hydraulic oil discharged from the pilot pump into the regenerated hydraulic motor as lubricating oil for the regenerated hydraulic motor. Hydraulic circuit. A check valve is further provided on the hydraulic pump side than a branch point with the regeneration pipeline on the hydraulic supply path, and further blocks a flow of hydraulic oil discharged from the first oil chamber to the hydraulic pump side. The hydraulic circuit for a work machine according to any one of claims 1 to 4, further comprising: A part of the hydraulic oil that is further branched from the hydraulic pump side than the branch point with the regeneration pipe on the hydraulic supply path is supplied to the second oil chamber. A second regeneration conduit to
A flow rate control valve that is interposed on the second regeneration pipeline and that controls the flow rate of the hydraulic fluid flowing through the second regeneration pipeline in accordance with the flow rate of the hydraulic fluid discharged from the first oil chamber. The hydraulic circuit for a work machine according to any one of claims 1 to 4, further comprising:

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