JP2004116656A - Pressure oil energy recovery/regeneration device - Google Patents

Pressure oil energy recovery/regeneration device Download PDF

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Publication number
JP2004116656A
JP2004116656A JP2002280904A JP2002280904A JP2004116656A JP 2004116656 A JP2004116656 A JP 2004116656A JP 2002280904 A JP2002280904 A JP 2002280904A JP 2002280904 A JP2002280904 A JP 2002280904A JP 2004116656 A JP2004116656 A JP 2004116656A
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JP
Japan
Prior art keywords
pressure
hydraulic pump
pressure oil
hydraulic
merging
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Application number
JP2002280904A
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Japanese (ja)
Inventor
Kazuhiro Maruta
Shinobu Nagura
Nobusane Yoshida
丸田 和弘
吉田 伸実
名倉 忍
Original Assignee
Komatsu Ltd
株式会社小松製作所
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Filing date
Publication date
Application filed by Komatsu Ltd, 株式会社小松製作所 filed Critical Komatsu Ltd
Priority to JP2002280904A priority Critical patent/JP2004116656A/en
Publication of JP2004116656A publication Critical patent/JP2004116656A/en
Withdrawn legal-status Critical Current

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Abstract

<P>PROBLEM TO BE SOLVED: To improve lever operability by accurately changing an output pressure of a pressure transducing part with favorable responsiveness in response to fluctuation of a discharge pressure of a main hydraulic pump. <P>SOLUTION: When the discharge pressure P3 of the main hydraulic pump 2 fluctuates, a flow control valve 21 is operated instead of changing a swash plate of a hydraulic pump 12, and a fore and aft differential pressure ΔP of a fixed restrictor 22 is maintained at a certain differential pressure ΔP2. By this, a pressure (an upstream pressure Pa of the fixed restrictor 22) in a junction passage 15 follows the fluctuation of the discharge pressure P3 (a downstream pressure Pb of the fixed restrictor 22) of the main hydraulic pump 2. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an apparatus for recovering and regenerating energy of return pressure oil flowing out of a hydraulic actuator.
[0002]
[Prior art]
It has been proposed to apply a hydraulic oil energy recovery / regeneration device to a construction machine such as a hydraulic shovel. When operating a boom or the like, the hydraulic oil energy recovery / regeneration device recovers energy of the return hydraulic oil flowing out of the hydraulic actuator and regenerates it as energy for driving the hydraulic actuator.
[0003]
FIG. 5 shows a basic hydraulic circuit of the hydraulic oil energy recovery / regeneration device. In the hydraulic circuit shown in FIG. 5, the main hydraulic pump 2 is driven by the engine 1 and the hydraulic oil discharged from the main hydraulic pump 2 is supplied to the hydraulic actuator via the hydraulic oil supply line 3, the directional control valve 4, and the line 7a. Is supplied to one cylinder chamber 5 a of the hydraulic cylinder 5. When pressure oil is supplied to one cylinder chamber 5a of the hydraulic cylinder 5, the hydraulic cylinder 5 is driven, and the boom 6 as a load is operated. When the pressure oil is supplied to one cylinder chamber 5a of the hydraulic cylinder 5, the return pressure oil flows out of the other cylinder chamber 5b and passes through the pipe 7b, the recovery valve 9, and the recovery pipe 8 to the pressure converter. 90. The pressure conversion unit 90 includes a hydraulic motor 11 and a hydraulic pump 12, and the rotary shafts of the hydraulic motor 11 and the hydraulic pump 12 are connected to each other. The hydraulic motor 11 is driven by the return pressure oil flowing into the hydraulic motor 11. When the hydraulic motor 11 is driven, the hydraulic pump 12 is driven, and pressure oil is discharged from the hydraulic pump 12. The pressure oil discharged from the hydraulic pump 12 is joined to the pressure oil supply line 3 via the junction line 15. The pressure oil joined to the pressure oil supply pipe 3 is supplied to the hydraulic cylinder 5 together with the pressure oil discharged from the main hydraulic pump 2.
[0004]
In the hydraulic circuit of FIG. 5, the pressure of the return pressure oil flowing out of the hydraulic cylinder 5 and the pressure of the pressure oil discharged from the hydraulic pump 2 are different. Therefore, when the return pressure oil joins the pressure oil discharged from the hydraulic pump 2, the pressure of the return pressure oil needs to be substantially the same as the pressure oil discharged from the main hydraulic pump 2.
[0005]
The pressure converter 90 is provided to make the pressure of the return pressure oil substantially equal to the pressure of the pressure oil discharged from the main hydraulic pump 2.
[0006]
The pressure of the pressure oil flowing into the hydraulic motor 11 is P1 (kg / cm 2 ), the flow rate is Q1 (cm 3 / min), and the pressure of the pressure oil discharged from the hydraulic motor 12 is P2 (kg / cm 2 ). , And the flow rate is Q2 (cm 3 / min), the following equation (1) is established between them in a balanced state where the rotational speed is constant.
[0007]
P1 × Q1 = P2 × Q2 (1)
If the capacity of the hydraulic motor 11 is q1 (cm 3 / rev), the capacity of the hydraulic pump 12 is q2 (cm 3 / rev), and the rotation speeds of the hydraulic motor 11 and the hydraulic pump 12 are n (rpm), the following (2) ) And (3) hold.
[0008]
Q1 = n · q1 (2)
Q2 = n · q2 (3)
However, efficiency losses are ignored for simplicity.
[0009]
The hydraulic motor 11 and the hydraulic pump 12 are variable displacement type motors and pumps. q2 changes.
[0010]
Therefore, as is apparent from the above equations (1), (2), and (3), by controlling the position of the capacity changing portion of the hydraulic motor 11 or the hydraulic pump 12, the pressure oil flowing into the hydraulic motor 11 is controlled. The ratio between the pressure P1 and the pressure P2 of the pressure oil discharged from the hydraulic pump 12, that is, the pressure conversion ratio P2 / P1 can be changed.
[0011]
It is assumed that the hydraulic oil energy recovery / regeneration device of FIG. 5 is mounted on a hydraulic shovel.
[0012]
For example, when the boom is lowered, the hydraulic cylinder 5 contracts and a large amount of return pressure oil flows out of the cylinder chamber 5b. At this time, the recovery valve 9 is located at the open position 9a, and the return pressure oil flowing out of the hydraulic cylinder 5 flows into the pressure converter 90. Here, the pressure P3 in the pressure oil supply line 3 is detected, and the pressure conversion ratio P2 / P1 is set so that the discharge pressure P2 of the hydraulic pump 12 becomes substantially the same as the pressure P3 in the pressure oil supply line 3. Is controlled. That is, the position of the capacity change portion of the hydraulic motor 11 or the hydraulic pump 12 is controlled.
[0013]
As a result, the pressure P1 of the return pressure oil is converted to substantially the same pressure as the pressure in the pressure oil supply line 3 and discharged from the hydraulic pump 12 to join the pressure oil supply line 3.
[0014]
[Problems to be solved by the invention]
The load pressure of the hydraulic cylinder 5 varies according to the magnitude of the load on the boom 6, and the discharge pressure P3 of the main hydraulic pump 2 varies accordingly. If the pressure in the hydraulic oil supply line 3 follows the change in the load pressure of the hydraulic cylinder 5, a flow rate corresponding to the operation amount of the operation lever is supplied to the hydraulic cylinder 5, and the lever operability is improved.
[0015]
For this reason, in order to obtain stable lever operability, it is necessary to adjust the output pressure P2 of the pressure conversion unit 90 to the pump discharge pressure P3 that fluctuates rapidly and then to join the pressure oil supply pipe 3.
[0016]
However, the capacity changing portions of the hydraulic motor 11 and the hydraulic pump 12 constituting the pressure conversion section 90 have a problem that inertia is large and response of the capacity changing portion control is slow. That is, it takes time to set the displacement changing portion of the hydraulic motor 11 and the hydraulic pump 12 to a desired tilt angle, and the output pressure P2 of the pressure conversion unit 90 is delayed with the fluctuation of the discharge pressure P3 of the main hydraulic pump 2. Change. Such poor response cannot be eliminated due to the mechanical structure of the pump or motor.
[0017]
If the output pressure P2 of the pressure converter 90 cannot accurately follow the fluctuation of the discharge pressure P3 of the main hydraulic pump 2, the pressure in the hydraulic oil supply pipe 3 will not change according to the load pressure of the hydraulic cylinder 5. Become. For this reason, a flow rate according to the operation amount of the operation lever cannot be supplied to the hydraulic cylinder 5, and the hydraulic cylinder 5 moves at a speed different from the operator's intention, and the lever operability deteriorates.
[0018]
The present invention has been made in view of the above situation, and improves the lever operability by enabling the output pressure of the pressure conversion unit to accurately and responsively follow the fluctuation of the discharge pressure of the main hydraulic pump with good responsiveness. That is the problem to be solved.
[0019]
Means, actions, and effects for solving the problem
The first invention is
A main hydraulic pump (2),
A hydraulic actuator (5) that is supplied with pressure oil discharged from the main hydraulic pump (2) and is driven;
A recovery hydraulic motor (11) driven by the return pressure oil flowing out of the hydraulic actuator (5),
A regenerative hydraulic pump (12) driven by the recovery hydraulic motor (11) and a pressure oil discharged from the regenerative hydraulic pump (12) are supplied to a pressure discharged from the main hydraulic pump (2). A merging line (15) for merging with oil;
A throttle (22) provided in the merging pipe (15);
A pressure oil energy recovery / regeneration device comprising a flow control valve (21) for adjusting a flow rate passing through the throttle (22) so that a differential pressure across the throttle (22) becomes a constant differential pressure. Features.
[0020]
The second invention is
A main hydraulic pump (2),
A hydraulic actuator (5) that is supplied with pressure oil discharged from the main hydraulic pump (2) and is driven;
A recovery hydraulic motor (11) driven by the return pressure oil flowing out of the hydraulic actuator (5),
A regenerative hydraulic pump (12) driven by the recovery hydraulic motor (11) and a pressure oil discharged from the regenerative hydraulic pump (12) are supplied to a pressure discharged from the main hydraulic pump (2). A merging line (15) for merging with oil;
Discharge pressure detecting means (42) for detecting a discharge pressure of pressure oil discharged from the main hydraulic pump (2);
Pressure control means (10, 30) for adjusting the pressure of the pressure oil discharged from the regenerative hydraulic pump (12) to a pressure higher than the discharge pressure detected by the discharge pressure detection means (42);
Rotation speed detection means (41) for detecting the rotation speed of the recovery hydraulic motor (11) or the regenerative hydraulic pump (12);
Flow rate calculating means for calculating the flow rate of pressure oil to be flown to the merging line (15) based on the rotation speed detected by the rotation speed detecting means (41) and the capacity of the regenerative hydraulic pump (12). (40)
A fixed throttle (22) provided in the merging conduit (15);
A flow control valve provided in the merging conduit (15) for controlling the differential pressure across the fixed throttle (22) to be a differential pressure across the flow calculated by the flow rate calculating means (40). (21).
[0021]
The first invention and the second invention will be described with reference to FIG.
[0022]
For example, when the boom (load) 6 is lowered, the hydraulic cylinder (hydraulic actuator) 5 is retracted and a large amount of return pressure oil flows out of the cylinder chamber 5b. At this time, the recovery valve 9 is located at the open position 9a, and the return pressure oil flowing out of the hydraulic cylinder 5 flows into the pressure conversion unit 10.
[0023]
Here, the discharge pressure P3 of the main hydraulic pump 2 is detected by the pressure sensor 42, the output pressure P2 of the pressure converter 10 is adjusted to a pressure P3 + α higher than the discharge pressure P3 of the main hydraulic pump 2, and The set pressure of the valve 30 is set to a pressure P3 + α higher than the discharge pressure of the main hydraulic pump 2.
[0024]
The hydraulic motor 11 and the hydraulic pump 12 of the pressure converter 10 rotate at the rotation speed n (rpm) by the energy of the return pressure oil flowing out of the hydraulic cylinder 5. The rotation speed n of the hydraulic motor 11 and the hydraulic pump 12 is detected by a rotation sensor 41.
[0025]
The capacity q2 of the hydraulic pump 12 is detected by the swash plate angle sensor 43 as the swash plate tilt angle of the hydraulic pump 12.
[0026]
The rotation speed n of the hydraulic pump 12 detected by the rotation sensor 41 and the capacity q2 of the hydraulic pump 12 detected by the swash plate angle sensor 43 are input to the controller 40, and based on the rotation speed n and the capacity q2, The flow rate Q2 to be discharged from the pump 12 (= n · q2), that is, the flow rate Q2 of the pressure oil to flow through the merging line 15 is calculated according to the above equation (3).
[0027]
A fixed throttle 22 and a flow control valve 21 are provided as a flow control unit 20 in the merging conduit 15. Assuming that the pressure on the upstream side of the fixed throttle 22 is Pa and the pressure on the downstream side is Pb, the pressure Pa on the upstream side is applied to the pilot port 21b of the flow control valve 21, and the pressure Pb on the downstream side is opposed to the pilot port 21b. Side pilot port 21a. A spring 21c is provided on the same side as the pilot port 21a, and the spring force is K. A command signal i is input from the controller 40 to the electromagnetic solenoid 21d on the same side as the pilot port 21b.
[0028]
In order for the flow rate Q2 calculated by the controller 40 to pass through the fixed throttle 22, the differential pressure ΔP across the fixed throttle 22 is represented by the following formula (A), where A is the opening area (diameter area) of the fixed throttle 22, and c is the flow coefficient. The difference pressure ΔP2 determined in 4) may be used.
[0029]
Q2 = c · A · √ (ΔP2) (4)
In order to make the pressure difference ΔP across the fixed throttle 22 constant, a force balance relationship represented by the following equation (5) may be established between the forces acting on the flow control valve 21. . However, the pressure receiving area of the pilot ports 21a and 21b is S.
[0030]
S (Pa−Pb) = K−i (5)
Here, the differential pressure ΔP before and after the fixed throttle 22 must be set to the differential pressure ΔP2 obtained from the above equation (4), so that the following equation (6) is established.
[0031]
Ki = [Delta] P2 / S (6)
The controller 40 substitutes the calculated flow rate Q2 into the above equation (4) to obtain ΔP2, substitutes the obtained ΔP2 into the above equation (6) to obtain a command signal i, and uses the command signal i as a flow rate control. Output to the valve 21. As a result, the flow control valve 21 operates according to the above equation (5), the differential pressure ΔP across the fixed throttle 22 becomes a constant differential pressure ΔP2, and the fixed flow rate Q2 passes through the fixed throttle 22, that is, the merging line 15. . As a result, the pressure in the merging line 15 (upstream pressure Pa of the fixed throttle 22) becomes substantially the same as the discharge pressure P3 of the main hydraulic pump 2 (downstream pressure Pb of the fixed throttle 22), and the pressure oil supply line 3 To join. When the discharge pressure P3 of the main hydraulic pump 2 fluctuates, the flow control valve 21 operates, so that the swash plate of the hydraulic pump 12 is changed to change the pressure in the merging line 15 (upstream pressure Pa of the fixed throttle 22). Need not follow the fluctuation of the discharge pressure P3 of the main hydraulic pump 2 (the downstream pressure Pb of the fixed throttle 22).
[0032]
The flow control valve 21 has a quicker response than a pump or a motor, and follows the fluctuation of the discharge pressure P3 of the main hydraulic pump 2 accurately. Therefore, lever operability is improved.
[0033]
The third invention is
A main hydraulic pump (2),
A hydraulic actuator (5) that is supplied with pressure oil discharged from the main hydraulic pump (2) and is driven;
A recovery hydraulic motor (11) driven by the return pressure oil flowing out of the hydraulic actuator (5),
A regenerative hydraulic pump (12) driven by the recovery hydraulic motor (11) and a pressure oil discharged from the regenerative hydraulic pump (12) are supplied to a pressure discharged from the main hydraulic pump (2). A merging line (15) for merging with oil;
Discharge pressure detecting means (42) for detecting a discharge pressure of pressure oil discharged from the main hydraulic pump (2);
Pressure control means (10, 30) for adjusting the pressure of the pressure oil discharged from the regenerative hydraulic pump (12) to a pressure higher than the discharge pressure detected by the discharge pressure detection means (42);
Rotation speed detection means (41) for detecting the rotation speed of the recovery hydraulic motor (11) or the regenerative hydraulic pump (12);
Flow rate calculating means for calculating the flow rate of pressure oil to be flown to the merging line (15) based on the rotation speed detected by the rotation speed detecting means (41) and the capacity of the regenerative hydraulic pump (12). (40)
A variable throttle (62) provided in the merging pipe (15);
A flow control valve (61) provided in the merging conduit (15) and controlling the differential pressure across the variable throttle (22) to be a constant differential pressure;
A control unit for controlling an opening area of the variable throttle (62) so as to have an opening area corresponding to the flow rate calculated by the flow rate calculation unit (40). Features.
[0034]
In the third invention, as shown in FIG. 3, a variable throttle 62 and a flow control valve 61 are provided as a flow control unit 20 in the merging pipe 15. Assuming that the pressure on the upstream side of the variable throttle 62 is Pa and the pressure on the downstream side is Pb, the pressure Pa on the upstream side is applied to the pilot port 61b of the flow control valve 61, and the pressure Pb on the downstream side is opposed to the pilot port 61b. Side pilot port 61a. A spring 61c is provided on the same side as the pilot port 61a, and the spring force is K.
[0035]
In order for the flow rate Q2 calculated by the controller 40 to pass through the variable throttle 62, the opening area (throttle area) A of the variable throttle 62 is determined by the following equation (7), where ΔP is the differential pressure across the variable throttle 62. It is sufficient that the opening area A2 is as large as possible.
[0036]
Q2 = c · A2 · √ (ΔP) (7)
In order to make the differential pressure ΔP across the variable throttle 62 constant, it is only necessary that the relationship between the forces acting on the flow control valve 61 be balanced by the following equation (8). . However, the pressure receiving area of the pilot ports 61a and 61b is S.
[0037]
S (Pa−Pb) = K (8)
The controller 40 calculates the opening area A2 by substituting the calculated flow rate Q2 and K / S (= ΔP) in the above equation (8) into the above equation (7), and changes the opening area A of the variable throttle 62 to A2. Let it. As a result, the flow control valve 61 operates according to the above equation (8), the differential pressure ΔP across the variable throttle 62 becomes a constant differential pressure, and the constant flow rate Q2 passes through the variable throttle 62, that is, the merging line 15. As a result, the pressure in the merging pipeline 15 (upstream pressure Pa of the variable throttle 62) becomes substantially the same as the discharge pressure P3 of the main hydraulic pump 2 (downstream pressure Pb of the variable throttle 62), and the pressure oil supply pipeline 3 To join. When the discharge pressure P3 of the main hydraulic pump 2 fluctuates, the flow control valve 61 operates, so that the swash plate of the hydraulic pump 12 is changed to change the pressure in the merging line 15 (the upstream pressure Pa of the variable throttle 62). Need to follow the fluctuation of the discharge pressure P3 of the main hydraulic pump 2 (the downstream pressure Pb of the variable throttle 62).
[0038]
The flow control valve 61 has a quicker response than a pump or a motor, and accurately follows the fluctuation of the discharge pressure P3 of the main hydraulic pump 2. Therefore, lever operability is improved.
[0039]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of a pressure oil energy recovery / regeneration device according to the present invention will be described with reference to the drawings.
[0040]
FIG. 1 shows a hydraulic circuit of the embodiment. In the embodiment, a hydraulic circuit mounted on a hydraulic shovel is assumed.
[0041]
As shown in FIG. 1, the main hydraulic pump 2 is a variable displacement hydraulic pump, which is driven by the engine 1 and changes its displacement by changing the tilt angle of the swash plate. The main hydraulic pump 2 only needs to be a variable displacement type, and need not be a swash plate type. Note that an electric motor may be used instead of the engine 1. The direction control valve 4 controls the flow rate of the pressure oil supplied to the hydraulic cylinder 5 and controls the direction of the flow of the pressure oil discharged from the main hydraulic pump 2 so that the pressure oil is supplied to one of the pipelines 7a and 7b. Supply.
[0042]
The hydraulic oil discharged from the main hydraulic pump 2 is supplied via the hydraulic oil supply line 3, the directional control valve 4, the line 7a or the line 7b to one of the cylinder chambers 5a of the hydraulic cylinder 5, which is a hydraulic actuator, or the other cylinder. It is supplied to the chamber 5b. The pressure oil supply line 3 is provided with a pressure sensor 42 for detecting the pressure P3 of the pressure oil discharged from the main hydraulic pump 2.
[0043]
When pressure oil is supplied to one of the cylinder chambers 5a of the hydraulic cylinder 5, the hydraulic cylinder 5 is driven to retract, and the boom 6 operates in a downward direction. When pressure oil is supplied to the other cylinder chamber 5b of the hydraulic cylinder 5, the hydraulic cylinder 5 is driven to extend, and the boom 6 operates in the upward direction.
[0044]
A recovery valve 9 is provided in the pipe 7b, and communication with the direction control valve 4 or communication with the pressure conversion unit 10 via the recovery pipe 8 is switched.
[0045]
When the collection valve 9 is in the open position 9a, the cylinder chamber 5b of the hydraulic cylinder 5 communicates with the inflow port 11a of the hydraulic motor 11 through the pipe 7b, the collection valve 9, and the collection pipe 8, and the collection valve 9 is closed. In the position 9b, the cylinder chamber 5b of the hydraulic cylinder 5 communicates with the tank 24 via the pipe 7b, the recovery valve 9, and the direction control valve 4.
[0046]
The pressure conversion unit 10 includes a hydraulic motor 11 and a hydraulic pump 12, and the rotary shafts of the hydraulic motor 11 and the hydraulic pump 12 are connected to each other. A rotation sensor 41 for detecting the number of rotations n (rpm) of the hydraulic motor 11 and the hydraulic pump 12 is provided on the rotating shaft of the hydraulic motor 11 and the hydraulic pump 12. The hydraulic pump 12 is provided with a swash plate angle sensor 43 that detects the displacement q2 (cm 3 / rev) of the hydraulic pump 12 by detecting the tilt angle of the swash plate of the hydraulic pump 12.
[0047]
The discharge port 12b of the hydraulic pump 12 communicates with the merging pipe 15. The junction line 15 communicates with the pressure oil supply line 3.
[0048]
The hydraulic motor 11 is driven by the return pressure oil flowing into the hydraulic motor 11. When the hydraulic motor 11 is driven, the hydraulic pump 12 is driven, and pressure oil is discharged from the hydraulic pump 12. The pressure oil discharged from the hydraulic pump 12 is joined to the pressure oil supply line 3 via the junction line 15. The pressure oil joined to the pressure oil supply pipe 3 is supplied to the hydraulic cylinder 5 together with the pressure oil discharged from the main hydraulic pump 2.
[0049]
The pressure of the return pressure oil flowing out of the hydraulic cylinder 5 and the pressure of the pressure oil discharged from the hydraulic pump 2 are different. Therefore, when the return pressure oil joins the pressure oil discharged from the main hydraulic pump 2, the pressure of the return pressure oil needs to be as high as the discharge pressure of the main hydraulic pump 2.
[0050]
The pressure converter 10 is provided to make the pressure P1 of the return pressure oil higher than the discharge pressure P3 of the main hydraulic pump 2 P3 + α.
[0051]
The hydraulic motor 11 is a variable displacement hydraulic motor, and the displacement q1 (cm 3 / rev) changes as the tilt angle of the swash plate changes. The hydraulic pump 12 is a variable displacement hydraulic pump, and the displacement q2 (cm 3 / rev) changes by changing the tilt angle of the swash plate. The hydraulic motor 11 and the hydraulic pump 12 may be of a variable displacement type, and need not be of a swash plate type.
[0052]
The pressure of the pressure oil flowing into the hydraulic motor 11 is P1 (kg / cm 2 ), the flow rate is Q1 (cm 3 / min), and the pressure of the pressure oil discharged from the hydraulic motor 12 is P2 (kg / cm 2 ). , And the flow rate is Q2 (cm 3 / min), the following equation (1) is established between them in a balanced state where the rotational speed is constant.
[0053]
P1 × Q1 = P2 × Q2 (1)
Further, when the rotation speeds of the hydraulic motor 11 and the hydraulic pump 12 are n (rpm), the following equations (2) and (3) are established.
[0054]
Q1 = n · q1 (2)
Q2 = n · q2 (3)
However, efficiency losses are ignored for simplicity.
[0055]
As is apparent from the above equations (1), (2) and (3), controlling the tilt angle of the swash plate of the hydraulic motor 11 or the hydraulic pump 12 allows the pressure of the hydraulic oil flowing into the hydraulic motor 11 to be controlled. The ratio between P1 and the pressure P2 of the pressure oil discharged from the hydraulic pump 12, that is, the pressure conversion ratio P2 / P1 can be changed. By changing the pressure conversion ratio, the discharge pressure P2 of the hydraulic pump 12 can be set to a pressure P3 + α higher than the discharge pressure P3 of the main hydraulic pump 2.
[0056]
A relief pipe 16 branches off from the junction pipe 15. The relief pipe line 16 is provided with a variable relief valve 30. The set pressure of the variable relief valve 30 is set to a pressure P3 + α higher than the discharge pressure P3 of the main hydraulic pump 2. The set pressure P + α of the variable relief valve 30 changes according to a command signal output from the controller 40. When the pressure in the merging line 15 exceeds the set pressure P + α of the variable relief valve 30, the pressure oil in the merging line 15 is relieved to the tank 24 and the pressure in the merging line 15 is maintained at the set pressure P + α.
[0057]
The merging line 15 is provided with a flow control unit 20. The flow rate control unit 20 controls the flow rate of the pressure oil passing through the merging line 15 to be a constant flow rate commanded by the controller 40. The flow control unit 20 includes a fixed throttle 22 on the merging conduit 15 and a flow control valve 21 provided upstream of the fixed throttle 22.
[0058]
Assuming that the pressure on the upstream side of the fixed throttle 22 is Pa and the pressure on the downstream side is Pb, the pressure Pa on the upstream side is applied to the pilot port 21b of the flow control valve 21, and the pressure Pb on the downstream side is opposed to the pilot port 21b. Side pilot port 21a. A spring 21c is provided on the same side as the pilot port 21a, and the spring force is K. A command signal i is input from the controller 40 to the electromagnetic solenoid 21d on the same side as the pilot port 21b.
[0059]
The check valve 23 is provided on the downstream side of the fixed throttle 22, and is provided to prevent the pressure oil in the pressure oil supply pipe 3 from flowing back to the junction pipe 15.
[0060]
Next, the operation of the hydraulic circuit of FIG. 1 will be described.
[0061]
When the boom 6 is lowered, the hydraulic cylinder 5 is retracted and a large amount of return pressure oil flows out of the cylinder chamber 5b. At this time, the recovery valve 9 is located at the open position 9a, and the return pressure oil flowing out of the hydraulic cylinder 5 flows into the pressure conversion unit 10. Here, the pressure P3 in the pressure oil supply pipe 3 is detected by the pressure sensor 42, and the detected pressure P3 of the pressure sensor 42 is input to the controller 40. The controller 40 controls the pressure conversion ratio P2 / P1 based on the input detected pressure P3 such that the discharge pressure P2 of the hydraulic pump 12 becomes a pressure P3 + α higher than the pressure P3 in the pressure oil supply pipe 3. . That is, the tilt angle of the swash plate of the hydraulic motor 11 or the hydraulic pump 12 is controlled.
[0062]
As a result, the pressure P1 of the return pressure oil is converted to a pressure P3 + α higher than the pressure P3 in the pressure oil supply pipe 3 and discharged from the hydraulic pump 12.
[0063]
Further, the controller 40 generates a command signal based on the input detected pressure P3, outputs the command signal to the variable relief valve 30, and changes the set pressure of the variable relief valve 30 to a pressure P3 + α higher than the discharge pressure P3 of the main hydraulic pump 2. Set.
[0064]
The hydraulic motor 11 and the hydraulic pump 12 of the pressure converter 10 rotate at the rotation speed n (rpm) by the energy of the return pressure oil flowing out of the hydraulic cylinder 5. The rotation speed n of the hydraulic motor 11 and the hydraulic pump 12 is detected by a rotation sensor 41.
[0065]
The capacity q2 of the hydraulic pump 12 is detected by the swash plate angle sensor 43 as the swash plate tilt angle of the hydraulic pump 12.
[0066]
The rotation speed n of the hydraulic pump 12 detected by the rotation sensor 41 and the capacity q2 of the hydraulic pump 12 detected by the swash plate angle sensor 43 are input to the controller 40, and based on the rotation speed n and the capacity q2, The flow rate Q2 to be discharged from the pump 12 (= n · q2), that is, the flow rate Q2 of the pressure oil to flow through the merging line 15 is calculated according to the above equation (3).
[0067]
In order for the flow rate Q2 calculated by the controller 40 to pass through the fixed throttle 22, the differential pressure ΔP across the fixed throttle 22 is represented by the following formula (A), where A is the opening area (diameter area) of the fixed throttle 22, and c is the flow coefficient. The difference pressure ΔP2 determined in 4) may be used.
[0068]
Q2 = c · A · √ (ΔP2) (4)
In order to make the pressure difference ΔP across the fixed throttle 22 constant, a force balance relationship represented by the following equation (5) may be established between the forces acting on the flow control valve 21. . However, the pressure receiving area of the pilot ports 21a and 21b is S.
[0069]
S (Pa−Pb) = K−i (5)
Here, the differential pressure ΔP before and after the fixed throttle 22 must be set to the differential pressure ΔP2 obtained from the above equation (4), so that the following equation (6) is established.
[0070]
(K−i) / S = ΔP2 (6)
The controller 40 substitutes the calculated flow rate Q2 into the above equation (4) to obtain ΔP2, substitutes the obtained ΔP2 into the above equation (6) to obtain a command signal i, and uses the command signal i as a flow rate control. Output to the valve 21.
[0071]
As a result, the flow control valve 21 operates according to the above equation (5), the differential pressure ΔP across the fixed throttle 22 becomes a constant differential pressure ΔP2, and the fixed flow rate Q2 passes through the fixed throttle 22, that is, the merging line 15. . As a result, the pressure in the merging line 15 (upstream pressure Pa of the fixed throttle 22) becomes substantially the same as the discharge pressure P3 of the main hydraulic pump 2 (downstream pressure Pb of the fixed throttle 22), and the pressure oil supply line 3 To join.
[0072]
When the discharge pressure P3 of the main hydraulic pump 2 changes, the flow control valve 21 operates. That is, when the pressure P3 of the pressure oil supply pipe 3 decreases, the downstream pressure Pb of the fixed throttle 22 decreases, and the differential pressure ΔP across the fixed throttle 22 increases. Therefore, the flow control valve 21 operates to reduce the differential pressure across the fixed throttle 22 and balances at a valve position where the differential pressure ΔP across the fixed throttle 22 matches the constant differential pressure ΔP2. Thereafter, the tilt angle of the swash plate is adjusted so that the discharge pressure P2 of the hydraulic pump 12 and the pressure in the merged pipe 15 become a pressure P3 + α higher than the pressure P3 in the pressurized oil supply pipe 3. At the same time, the set pressure of the variable relief valve 30 is reduced.
[0073]
When the pressure P3 of the pressure oil supply pipe 3 increases, the downstream pressure Pb of the fixed throttle 22 increases, and the pressure difference ΔP across the fixed throttle 22 decreases. Therefore, the flow control valve 21 operates to increase the differential pressure across the fixed throttle, and balances at a valve position where the differential pressure ΔP across the fixed throttle 22 matches the constant differential pressure ΔP2. Thereafter, the tilt angle of the swash plate is adjusted so that the discharge pressure P2 of the hydraulic pump 12 and the pressure in the merged pipe 15 become a pressure P3 + α higher than the pressure P3 in the pressurized oil supply pipe 3. At the same time, the set pressure of the variable relief valve 30 is increased.
[0074]
When the pressure P3 in the pressure oil supply line 3 becomes larger than the downstream pressure Pb of the fixed throttle 22, the check valve 23 operates, and the pressure oil in the pressure oil supply line 3 Prevent backflow into the interior.
[0075]
Further, when the discharge pressure P2 of the hydraulic pump 12 increases and exceeds the set pressure P3 + α of the variable relief valve 30, the pressure oil in the junction pipe 15 is relieved to the tank 24. Therefore, the pressure on the upstream side of the flow control valve 21 is maintained at the set pressure P3 + α of the variable relief valve 30.
[0076]
As described above, according to the present embodiment, when the discharge pressure P3 of the main hydraulic pump 2 fluctuates, the flow control valve 21 operates, so that the swash plate of the hydraulic pump 12 is changed to (The upstream pressure Pa of the fixed throttle 22) does not need to follow the fluctuation of the discharge pressure P3 of the main hydraulic pump 2 (the downstream pressure Pb of the fixed throttle 22). The flow control valve 21 has a quicker response than a pump or a motor, and follows the fluctuation of the discharge pressure P3 of the main hydraulic pump 2 accurately. Therefore, lever operability is improved.
[0077]
Another configuration example of the flow control unit 20 will be described with reference to FIGS. 2, 3, 4, and 5.
[0078]
The flow control unit 20 shown in FIG. 2 is the same as FIG. 1 in that a command signal i is applied from the controller 40 to the flow control valve 21, but the flow control valve 21 It differs in that it works. The flow control valve 21 operates such that the pressure difference ΔP between the pressure on the upstream side of the fixed throttle 22 and the pressure on the downstream side of the check valve 23 becomes a constant pressure difference ΔP2.
[0079]
The flow control unit 20 shown in FIG. 3 includes a variable throttle 62 and a flow control valve 61 provided upstream of the variable throttle 62. Assuming that the pressure on the upstream side of the variable throttle 62 is Pa and the pressure on the downstream side is Pb, the pressure Pa on the upstream side is applied to the pilot port 61b of the flow control valve 61, and the pressure Pb on the downstream side is opposed to the pilot port 61b. Side pilot port 61a. A spring 61c is provided on the same side as the pilot port 61a, and the spring force is K.
[0080]
In order for the flow rate Q2 calculated by the controller 40 to pass through the variable throttle 62, the opening area (throttle area) A of the variable throttle 62 is determined by the following equation (7), where ΔP is the differential pressure across the variable throttle 62. It is sufficient that the opening area A2 is as large as possible.
[0081]
Q2 = c · A2 · √ (ΔP) (7)
In order to make the differential pressure ΔP across the variable throttle 62 constant, it is only necessary that the relationship between the forces acting on the flow control valve 61 be balanced by the following equation (8). . However, the pressure receiving area of the pilot ports 61a and 61b is S.
[0082]
S (Pa−Pb) = K (8)
The controller 40 determines the opening area A2 by substituting the calculated flow rate Q2 and K / S (= ΔP) in the above equation (8) into the above equation (7), and changes the opening area A of the variable throttle 62 to A2. To control the aperture amount. As a result, the flow control valve 61 operates according to the above equation (8), the differential pressure ΔP across the variable throttle 62 becomes a constant differential pressure, and the constant flow rate Q2 passes through the variable throttle 62, that is, the merging line 15. As a result, the pressure in the merging pipeline 15 (upstream pressure Pa of the variable throttle 62) becomes substantially the same as the discharge pressure P3 of the main hydraulic pump 2 (downstream pressure Pb of the variable throttle 62), and the pressure oil supply pipeline 3 To join. When the discharge pressure P3 of the main hydraulic pump 2 fluctuates, the flow control valve 61 operates, so that the swash plate of the hydraulic pump 12 is changed to change the pressure in the merging line 15 (the upstream pressure Pa of the variable throttle 62). Need to follow the fluctuation of the discharge pressure P3 of the main hydraulic pump 2 (the downstream pressure Pb of the variable throttle 62).
[0083]
The flow control valve 61 has a quicker response than a pump or a motor, and accurately follows the fluctuation of the discharge pressure P3 of the main hydraulic pump 2. Therefore, lever operability is improved.
[0084]
4 is similar to FIG. 3 in that the opening area A of the variable throttle 62 is controlled by the controller 40, but the flow control valve 61 is It differs in that it works. The flow control valve 61 operates so that the differential pressure ΔP between the pressure on the upstream side of the variable throttle 62 and the pressure on the downstream side of the check valve 23 becomes a constant differential pressure K / S.
[0085]
In each of the above-described embodiments, the flow control valves 21 and 61 are provided on the upstream side of the fixed throttle 22 or the variable throttle 23. However, the flow control valves may be provided on the downstream side.
[Brief description of the drawings]
FIG. 1 is a diagram showing a hydraulic circuit according to an embodiment.
FIG. 2 is a diagram illustrating another configuration example of the flow control unit illustrated in FIG. 1;
FIG. 3 is a diagram illustrating another configuration example of the flow control unit illustrated in FIG. 1;
FIG. 4 is a diagram illustrating another configuration example of the flow control unit illustrated in FIG. 1;
FIG. 5 is a diagram showing a conventional hydraulic circuit.
[Explanation of symbols]
2 Main hydraulic pump 5 Hydraulic cylinder 11 Hydraulic motor 12 Hydraulic pump 21, 61, 71 Flow control valve 22 Fixed throttle 62 Variable throttle

Claims (3)

  1. A main hydraulic pump (2),
    A hydraulic actuator (5) that is supplied with pressure oil discharged from the main hydraulic pump (2) and is driven;
    A recovery hydraulic motor (11) driven by the return pressure oil flowing out of the hydraulic actuator (5),
    A regenerative hydraulic pump (12) driven by the recovery hydraulic motor (11) and a pressure oil discharged from the regenerative hydraulic pump (12) are supplied to a pressure discharged from the main hydraulic pump (2). A merging line (15) for merging with oil;
    A throttle (22) provided in the merging pipe (15);
    A pressure control valve (21) for adjusting a flow rate passing through the throttle (22) so that a differential pressure across the throttle (22) becomes a constant differential pressure; apparatus.
  2. A main hydraulic pump (2),
    A hydraulic actuator (5) that is supplied with pressure oil discharged from the main hydraulic pump (2) and is driven;
    A recovery hydraulic motor (11) driven by the return pressure oil flowing out of the hydraulic actuator (5),
    A regenerative hydraulic pump (12) driven by the recovery hydraulic motor (11) and a pressure oil discharged from the regenerative hydraulic pump (12) are supplied to a pressure discharged from the main hydraulic pump (2). A merging line (15) for merging with oil;
    Discharge pressure detecting means (42) for detecting a discharge pressure of pressure oil discharged from the main hydraulic pump (2);
    Pressure control means (10, 30) for adjusting the pressure of the pressure oil discharged from the regenerative hydraulic pump (12) to a pressure higher than the discharge pressure detected by the discharge pressure detection means (42);
    Rotation speed detection means (41) for detecting the rotation speed of the recovery hydraulic motor (11) or the regenerative hydraulic pump (12);
    Flow rate calculating means for calculating the flow rate of pressure oil to be flown to the merging line (15) based on the rotation speed detected by the rotation speed detecting means (41) and the capacity of the regenerative hydraulic pump (12). (40)
    A fixed throttle (22) provided in the merging conduit (15);
    A flow control valve provided in the merging conduit (15) for controlling the differential pressure across the fixed throttle (22) to be a differential pressure across the flow calculated by the flow rate calculating means (40). (21) A pressure oil energy recovery / regeneration device comprising:
  3. A main hydraulic pump (2),
    A hydraulic actuator (5) that is supplied with pressure oil discharged from the main hydraulic pump (2) and is driven;
    A recovery hydraulic motor (11) driven by the return pressure oil flowing out of the hydraulic actuator (5),
    A regenerative hydraulic pump (12) driven by the recovery hydraulic motor (11) and a pressure oil discharged from the regenerative hydraulic pump (12) are supplied to a pressure discharged from the main hydraulic pump (2). A merging line (15) for merging with oil;
    Discharge pressure detecting means (42) for detecting a discharge pressure of pressure oil discharged from the main hydraulic pump (2);
    Pressure control means (10, 30) for adjusting the pressure of the pressure oil discharged from the regenerative hydraulic pump (12) to a pressure higher than the discharge pressure detected by the discharge pressure detection means (42);
    Rotation speed detection means (41) for detecting the rotation speed of the recovery hydraulic motor (11) or the regenerative hydraulic pump (12);
    Flow rate calculating means for calculating the flow rate of pressure oil to be flown to the merging line (15) based on the rotation speed detected by the rotation speed detecting means (41) and the capacity of the regenerative hydraulic pump (12). (40)
    A variable throttle (62) provided in the merging pipe (15);
    A flow control valve (61) provided in the merging conduit (15) and controlling the differential pressure across the variable throttle (22) to be a constant differential pressure;
    Control means for controlling the opening area of the variable throttle (62) so as to have an opening area corresponding to the flow rate calculated by the flow rate calculation means (40). apparatus.
JP2002280904A 2002-09-26 2002-09-26 Pressure oil energy recovery/regeneration device Withdrawn JP2004116656A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
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Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2002280904A JP2004116656A (en) 2002-09-26 2002-09-26 Pressure oil energy recovery/regeneration device

Publications (1)

Publication Number Publication Date
JP2004116656A true JP2004116656A (en) 2004-04-15

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Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007327527A (en) * 2006-06-06 2007-12-20 Kayaba Ind Co Ltd Energy regeneration type power unit
JP2008032198A (en) * 2006-08-01 2008-02-14 Shin Caterpillar Mitsubishi Ltd Hydraulic circuit for hst system
CN101907525A (en) * 2010-07-09 2010-12-08 江麓机电科技有限公司 Testing system for recovering energy of hybrid power hydraulic excavator
JP2011002094A (en) * 2009-06-22 2011-01-06 Liebherr-Werk Nenzing Gmbh Hydraulic system
CN102094434A (en) * 2011-01-11 2011-06-15 浙江大学 System for differential recovery of potential energy of boom of oil liquid hybrid power excavating machine
CN103016466A (en) * 2012-12-24 2013-04-03 中联重科股份有限公司 Hydraulic oil supply unit, hydraulic power unit and oil supply control method of hydraulic oil supply unit
WO2015012340A1 (en) * 2013-07-24 2015-01-29 日立建機株式会社 Energy regeneration system for construction equipment
CN104358749A (en) * 2014-09-30 2015-02-18 徐州徐工挖掘机械有限公司 Energy recovery and utilization system for movable arm potential energy
WO2015173963A1 (en) * 2014-05-16 2015-11-19 日立建機株式会社 Hydraulic energy regeneration apparatus for machinery

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007327527A (en) * 2006-06-06 2007-12-20 Kayaba Ind Co Ltd Energy regeneration type power unit
JP2008032198A (en) * 2006-08-01 2008-02-14 Shin Caterpillar Mitsubishi Ltd Hydraulic circuit for hst system
JP2011002094A (en) * 2009-06-22 2011-01-06 Liebherr-Werk Nenzing Gmbh Hydraulic system
US9822806B2 (en) 2009-06-22 2017-11-21 Liebherr-Werk Nenzig GmbH Hydraulic system
CN101907525A (en) * 2010-07-09 2010-12-08 江麓机电科技有限公司 Testing system for recovering energy of hybrid power hydraulic excavator
CN102094434A (en) * 2011-01-11 2011-06-15 浙江大学 System for differential recovery of potential energy of boom of oil liquid hybrid power excavating machine
CN103016466A (en) * 2012-12-24 2013-04-03 中联重科股份有限公司 Hydraulic oil supply unit, hydraulic power unit and oil supply control method of hydraulic oil supply unit
WO2015012340A1 (en) * 2013-07-24 2015-01-29 日立建機株式会社 Energy regeneration system for construction equipment
US9926951B2 (en) 2013-07-24 2018-03-27 Hitachi Construction Machinery Co., Ltd. Energy regeneration system for construction machine
JPWO2015173963A1 (en) * 2014-05-16 2017-04-20 日立建機株式会社 Pressure oil energy regeneration device for work machines
WO2015173963A1 (en) * 2014-05-16 2015-11-19 日立建機株式会社 Hydraulic energy regeneration apparatus for machinery
US10280593B2 (en) 2014-05-16 2019-05-07 Hitachi Construction Machinery Co., Ltd. Hydraulic fluid energy regeneration device for work machine
CN104358749A (en) * 2014-09-30 2015-02-18 徐州徐工挖掘机械有限公司 Energy recovery and utilization system for movable arm potential energy

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