JP5817311B2 - Hybrid hydraulic system - Google Patents

Description

  The present invention relates to a hybrid hydraulic apparatus used for construction machines such as a hydraulic excavator.

  Conventionally, as a hybrid hydraulic apparatus, a hydraulic pump, a hydraulic actuator that is driven by oil discharged from the hydraulic pump, a regenerative hydraulic motor that is rotated by return oil from the hydraulic actuator, and a regenerative hydraulic motor that is driven There is a generator provided with the generator (see Japanese Patent Application Laid-Open No. 2002-275945: Patent Document 1).

  However, in the conventional hybrid hydraulic apparatus, since all the return oil from the hydraulic actuator flows into the regenerative hydraulic motor, the regenerative hydraulic motor and the regenerative hydraulic motor and A generator has to be selected, and there is a problem that the regenerative hydraulic motor and the generator become very large.

JP 2002-275945 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide a hybrid hydraulic apparatus that can reduce the size of a regenerative hydraulic motor and generator.

In order to solve the above problems, a hybrid hydraulic device of the present invention is
A hydraulic pump;
A hydraulic actuator driven by oil discharged from the hydraulic pump;
An operation unit for operating a supply amount of discharge oil supplied from the hydraulic pump to the hydraulic actuator;
The flow direction of the discharge oil supplied from the hydraulic pump to the hydraulic actuator is switched to switch the operation direction of the hydraulic actuator, and the opening degree is adjusted to adjust the speed of the hydraulic actuator. A control valve;
A regenerative hydraulic motor that rotates with return oil from the hydraulic actuator;
A generator driven by the regenerative hydraulic motor;
A pressure flow control valve that is provided in an oil return line that connects the hydraulic actuator and the regenerative hydraulic motor, and that controls the pressure and flow rate of the return oil supplied from the hydraulic actuator to the regenerative hydraulic motor;
A control device for changing the set pressure and set flow rate of the pressure flow control valve based on the magnitude of the operation of the operation unit ;
When the hydraulic actuator, the main control valve, and the pressure flow control valve are in one set, or
In the case where there are a plurality of sets of the hydraulic actuator, the main control valve and the pressure flow control valve, and only one set of the pressure flow control valves of the plurality of sets is open,
A throttle is connected to the oil return line that connects the hydraulic actuator and the regenerative hydraulic motor downstream of the pressure flow control valve in parallel to the regenerative hydraulic motor.
From the sum of the oil passage flow rate obtained from the differential pressure before and after the throttle and the oil passage flow rate obtained from the rotation speed of the regenerative hydraulic motor, all returns flowing downstream of the pressure flow control valve are obtained. having a return oil flow rate calculating means for calculating the flow rate of the oil is characterized in Rukoto.

  According to the hybrid hydraulic device of the present invention, the control device changes the set pressure and the set flow rate controlled by the pressure flow control valve based on the magnitude of the operation of the operation unit. When the magnitude of the operation of the part is large, the pressure flow control valve is set to a lower pressure in relation to the set pressure with respect to the flow rate to reduce the passage pressure loss, thereby maintaining the characteristics of the conventional control valve.

  As a result, the energy of the return oil can be recovered by the downstream regenerative hydraulic motor and generator while maintaining the characteristics of the conventional control valve. At this time, in order to control to a predetermined pressure by the pressure flow control valve, the pressure difference generated by the downstream regenerative hydraulic motor and the generator can be set to an arbitrary pressure equal to or lower than the set pressure of the pressure flow control valve. This allows the power generation amount to be set arbitrarily.

Therefore, the regenerative hydraulic motor and the generator can be selected in accordance with the return oil pressure, which is frequently used in actual work conditions, and the regenerative hydraulic motor and the generator can be downsized.
Further, the return oil flow rate calculation means is configured to calculate the pressure flow rate control from the sum of the oil flow rate obtained from the differential pressure before and after the restriction and the oil flow rate obtained from the rotation speed of the regenerative hydraulic motor. Since the flow rates of all return oils flowing downstream of the valve are obtained, the flow rates of all return oils can be easily obtained.

In addition , when there are a plurality of sets of the hydraulic actuator, the main control valve, and the pressure flow control valve, the control device can change the set pressure and set flow of each set of pressure flow control valves. While maintaining the characteristics, it is possible to combine the return oil and recover the energy by the regenerative hydraulic motor and the generator.

  Further, in the hybrid hydraulic device according to one embodiment, the oil return line connecting the hydraulic actuator and the regenerative hydraulic motor to the regenerative hydraulic motor downstream from the pressure flow control valve. A relief valve is connected in parallel.

  According to the hybrid hydraulic apparatus of this embodiment, since the relief valve is connected in parallel to the regenerative hydraulic motor, when return oil that exceeds the capacity of the regenerative hydraulic motor and the generator flows. The return oil can be released by the relief valve. Therefore, the regenerative hydraulic motor and the generator can be selected in accordance with the flow rate that is frequently used in actual working conditions, and the regenerative hydraulic motor and the generator can be downsized.

  In the hybrid hydraulic apparatus according to an embodiment, the oil return line connecting the hydraulic actuator and the regenerative hydraulic motor is disposed downstream of the pressure flow control valve and upstream of the regenerative hydraulic motor. A stop valve is connected to the side.

  According to the hybrid hydraulic device of this embodiment, since the stop valve is connected upstream of the regenerative hydraulic motor, the regenerative hydraulic pressure is generated by the stop valve when the regenerative hydraulic motor or the generator fails. The supply of return oil to the motor can be shut off.

  According to the hybrid hydraulic device of the present invention, the control device changes the set pressure and the set flow rate controlled by the pressure flow control valve based on the magnitude of the operation of the operation unit. While maintaining the characteristics of the valve, power can be generated by setting an arbitrary pressure and flow rate with the regenerative hydraulic motor and generator, thereby reducing the size of the regenerative hydraulic motor and generator.

It is a simplified lineblock diagram showing one embodiment of a hybrid type hydraulic device of the present invention. It is a graph which shows the pressure flow characteristic line of a pressure flow control valve. It is a simplified block diagram of a relief valve. It is a graph which shows the pressure flow characteristic line of a relief valve. It is a simplified block diagram of a diaphragm. It is a graph which shows the pressure flow characteristic line of a throttle.

  Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

  FIG. 1 is a simplified configuration diagram showing an embodiment of a hybrid hydraulic apparatus according to the present invention. As shown in FIG. 1, this hybrid hydraulic apparatus is used in a construction machine such as a hydraulic excavator, for example, and includes a hydraulic pump 1, a hydraulic actuator 8 driven by oil discharged from the hydraulic pump 1, and the hydraulic pressure A regenerative hydraulic motor 62 that rotates with return oil from the actuator 8 and a generator 63 that is driven by the regenerative hydraulic motor 62 are provided.

  The hydraulic pump 1 is a hydraulic pump such as a gear pump, a trochoid pump, a vane pump, or a piston pump, and sucks and discharges hydraulic oil from the oil tank 5. The hydraulic pump 1 is driven by the engine 4.

  The hydraulic actuator 8 is, for example, a cylinder that drives a boom, an arm, a bucket, or the like, and the cylinder rod is reciprocated in the vertical direction or the horizontal direction by hydraulic oil.

  A main control valve 2 is connected to a first line 51 as a discharge line from the hydraulic pump 1. The main control valve 2 switches the operating direction of the hydraulic actuator 8 by switching the flow direction of the discharge oil supplied from the hydraulic pump 1 to the hydraulic actuator 8. The main control valve 2 adjusts the opening degree to adjust the speed of the hydraulic actuator 8.

  The main control valve 2 is connected to the hydraulic pump 1 through a first line 51, and is connected to the hydraulic actuator 8 through second and third lines 52 and 53.

  The main control valve 2 has a first position S1, a second position S2, and a third position S3. In the first position S1, the first port P1 and the fourth port P4 communicate with each other, and the second port P2, the third port P3, the fifth port P5, and the sixth port P6 are cut off. At this time, the hydraulic oil discharged from the hydraulic pump 1 passes through the first and fourth ports P1 and P4, then flows through the fourth and fifth lines 54 and 55 and returns to the oil tank 5.

  In the second position S2, the second port P2 and the fifth port P5 communicate with each other, the third port P3 and the sixth port P6 communicate with each other, and the first port P1 and the fourth port P4 are blocked. It becomes a state. At this time, the hydraulic oil discharged from the hydraulic pump 1 passes through the second and fifth ports P2 and P5, then flows through the second line 52, and is supplied to one of the first cylinder chambers of the hydraulic actuator 8. .

  In the third position S3, the second port P2 and the sixth port P6 communicate with each other, the third port P3 and the fifth port P5 communicate with each other, and the first port P1 and the fourth port P4 are blocked. It becomes a state. At this time, the hydraulic oil discharged from the hydraulic pump 1 passes through the second and sixth ports P2 and P6, then flows through the third line 53, and is supplied to the other second cylinder chamber of the hydraulic actuator 8.

  The main control valve 2 is controlled by operating the operation unit 3. The operation unit 3 is, for example, an operation lever, and the operation of the operation unit 3 is sent to the control device 6 as a signal, and the control device 6 controls the main control valve 2 based on this signal.

  For example, the control device 6 sets the main control valve 2 at any one of the first, second, and third positions S1, S2, and S3 or an intermediate position thereof based on the operation direction of the operation unit 3. To do. That is, the control device 6 controls the passing direction and the opening degree of the main control valve 2 based on the magnitude of the operation of the operation unit 3 (for example, the operation width such as the movement amount of the lever). That is, the operation unit 3 operates the direction and supply amount of the discharged oil supplied from the hydraulic pump 1 to the hydraulic actuator 8 according to the magnitude of the operation.

  A first check valve 11 is provided in the first line 51. A sixth line 56 is connected between the first check valve 11 and the hydraulic pump 1. A relief valve 20 is provided in the sixth line 56 so that the pressure of the hydraulic oil in the first line 51 does not exceed a predetermined value.

  One end of seventh and eighth lines 57 and 58 is connected to the second line 52, and the other end of the seventh and eighth lines 57 and 58 is connected to the third line 53. The seventh line 57 is located closer to the hydraulic actuator 8 than the eighth line 58.

  The seventh line 57 is provided with first and second pressure flow control valves 21 and 22 so that the hydraulic pressure in the second and third lines 52 and 53 does not exceed a predetermined value. On the other hand, the eighth line 58 is provided with second and third check valves 12 and 13 to prevent negative pressure in the second and third lines 52 and 53.

  The first pressure flow control valve 21 has an inlet connected to the second line 52 via a seventh line 57, and a discharge outlet for discharging hydraulic oil flowing in from the inlet. The hydraulic oil discharged from the discharge port flows to the ninth line 59. A throttle 31 is provided on the downstream side of the discharge port, and the flow rate of oil passing through the throttle 31 is detected from the differential pressure before and after the throttle 31.

  The second pressure flow control valve 22 has an inflow port connected to the third line 53 via a seventh line 57 and an outflow port for discharging hydraulic oil flowing in from the inflow port. The hydraulic oil discharged from the discharge port flows to the ninth line 59. A throttle 32 is provided on the downstream side of the discharge port, and the flow rate of oil passing through the throttle 32 is detected from the differential pressure before and after the throttle 32.

  The ninth line 59 is provided with the regenerative hydraulic motor 62. That is, the first and second pressure flow control valves 21 and 22 are provided in the seventh and ninth lines 57 and 59 as oil return lines that connect the hydraulic actuator 8 and the regenerative hydraulic motor 62. .

  The pressure flow control valves 21 and 22 are, for example, external drain type electromagnetic proportional relief valves, and control the pressure and flow rate of return oil supplied from the hydraulic actuator 8 to the regenerative hydraulic motor 62. The drains of the pressure flow control valves 21 and 22 communicate with the oil tank 5. The set pressure and set flow rate of the pressure flow control valves 21 and 22 are changed by the control device 6.

  A stop valve 41 is provided in the second line 52 between the connection point of the eighth line 58 and the main control valve 2. The stop valve 41 is, for example, an electromagnetic valve. By shutting off the second line 52, the return oil from one first cylinder chamber of the hydraulic actuator 8 flows into the seventh line 57 side, while the second line 52 By connecting the line 52, the return oil from one of the first cylinder chambers of the hydraulic actuator 8 flows into the main control valve 2 side.

  A stop valve 42 is provided in the third line 53 between the connection point of the eighth line 58 and the main control valve 2. The stop valve 42 is, for example, an electromagnetic valve. By shutting off the third line 53, the return oil from the other second cylinder chamber of the hydraulic actuator 8 flows into the seventh line 57 side, while the third line 53 By connecting the line 53, the return oil from the other second cylinder chamber of the hydraulic actuator 8 is caused to flow into the main control valve 2 side.

  Therefore, by switching the stop valves 41 and 42, it is possible to select the flow of the return oil from the hydraulic actuator 8 to either the regeneration hydraulic motor 62 or the main control valve 2, and the generator 63 Even when the battery is fully charged or an abnormality occurs in the regenerative hydraulic motor 62 or the generator 63, the operation can be continued as usual by switching the stop valves 41 and 42.

  A stop valve 43 is connected to the ninth line 59 upstream of the regenerative hydraulic motor 62. The stop valve 43 is, for example, an electromagnetic valve, and allows the return oil from the hydraulic actuator 8 to flow into the regenerative hydraulic motor 62 side by connecting the ninth line 59 while blocking the ninth line 59. Thus, the return oil from the hydraulic actuator 8 is prevented from flowing into the regenerative hydraulic motor 62. Therefore, when the regenerative hydraulic motor 62 or the generator 63 fails, the supply of return oil to the regenerative hydraulic motor 62 can be blocked by the stop valve 43.

  A tenth line 60 communicating with the oil tank 5 is connected to the ninth line 59 on the upstream side of the stop valve 43. The seventh, ninth, and tenth lines 57, 59, and 60 constitute an oil return line that connects the hydraulic actuator 8 and the regenerative hydraulic motor 62.

  The tenth line 60 is provided with a relief valve 23. That is, the relief valve 23 is connected to the regenerative hydraulic motor 62 in parallel. Accordingly, since the relief valve 23 is connected in parallel to the regenerative hydraulic motor 62, when return oil exceeding the capacity of the regenerative hydraulic motor 62 and the generator 63 flows, the relief valve 23 supplies the return oil. The oil tank 5 can be escaped.

  The tenth line 60 is provided with a throttle 33 on the downstream side of the relief valve 23. That is, the throttle 33 is connected in parallel to the regenerative hydraulic motor 62. A pressure sensor 45 is connected to the upstream side of the throttle 33. A return oil flow rate calculation means 66 is electrically connected to the pressure sensor 45 and the regenerative hydraulic motor 62. The return oil flow rate calculation means 66 calculates the pressure flow rate control from the sum of the oil flow rate Q2 obtained from the differential pressure before and after the throttle 33 and the oil flow rate Q1 obtained from the rotational speed of the regenerative hydraulic motor 62. The flow rate Q of all return oil that has flowed downstream of the valves 21 and 22 is obtained. Therefore, the flow rate Q of all return oils can be easily obtained.

  An inverter 64 is connected to the generator 63, and the inverter 64 controls the frequency of the current supplied to the generator 63. By changing this frequency, the rotational speed or torque of the generator 63 can be controlled to adjust the power generation amount of the generator 63.

  A power storage device 65 is connected to the generator 63 via an inverter 64, and the power storage device 65 stores electricity generated by the generator 63. This electricity is used in an electric device (not shown) to obtain an energy saving effect.

  Next, the characteristics of the flow control valves 21 and 22 will be described. The control device 6 changes the set pressure and the set flow rate of the pressure flow control valves 21 and 22 based on the magnitude of operation of the operation unit 3 (operation width).

  Specifically, when the magnitude of the operation of the operation unit 3 is large, the relationship between the pressure and flow rate control valves 21 and 22 is set to a lower pressure to reduce the passage pressure loss. That is, as shown in FIG. 2, the pressure flow characteristic lines of the pressure flow control valves 21 and 22 are changed to L3, L2, and L1 as the operation of the operation unit 3 increases. Thereby, the relationship between the pressure and the flow rate realized by the conventional control valve and the relief valve is maintained.

  As a result, when the amount of return oil discharged from the hydraulic actuator 8 increases, the amount of return oil supplied to the regenerative hydraulic motor 62 can be reduced, while the return oil discharged from the hydraulic actuator 8 is discharged. When the amount decreases, the amount of return oil supplied to the regeneration hydraulic motor 62 can be increased.

  In other words, the pressure flow control valves 21 and 22 perform pressure control with a target equivalent to a characteristic obtained by synthesizing the characteristic of the relief valve 101 in FIG. 3A and the characteristic of the throttle 102 in FIG. 4A. The pressure-flow characteristic curve of the relief valve 101 in FIG. 3A is a straight line with a substantially constant pressure, as shown in FIG. 3B. The pressure flow characteristic line of the throttle 102 in FIG. 4A is a curve as shown in FIG. 4B.

  According to the hybrid hydraulic apparatus having the above configuration, the control device 6 changes the set pressure and the set flow rate controlled by the pressure / flow rate control valves 21 and 22 based on the magnitude of the operation of the operation unit 3. Therefore, the energy of the return oil can be recovered by the downstream regeneration hydraulic motor 62 and the generator 63 while maintaining the characteristics of the conventional control valve. At this time, in order to control to a predetermined pressure by the pressure flow control valves 21, 22, the pressure difference generated by the downstream regenerative hydraulic motor 62 and the generator 63 is set to an arbitrary pressure below the set pressure of the pressure flow control valve. Thus, the power generation amount can be arbitrarily set.

  Therefore, the regenerative hydraulic motor 62 and the generator 63 can be selected in accordance with the return oil pressure, which is frequently used in actual work conditions, and the regenerative hydraulic motor 62 and the generator 63 can be reduced in size. And the greatest cost-effectiveness can be expected.

  In addition, this invention is not limited to the above-mentioned embodiment. For example, the hydraulic actuator, the main control valve, and the pressure flow control valve (specifically, the region Z surrounded by the phantom line in FIG. 1) is one set in the embodiment, but may be a plurality of sets. . In this way, even if there are multiple sets, the control device can change the set pressure and set flow rate of each set of pressure flow control valves, so that the return oil can be merged for regeneration while maintaining the characteristics of the conventional control valve. It is possible to recover energy by a hydraulic motor and a generator.

  In addition to the external drain-type electromagnetic proportional relief valve, the pressure flow control valve controls the pressure and flow rate of the return oil supplied from the hydraulic actuator to the regenerative hydraulic motor. Any valve that can change the set flow rate may be used.

  The relief valve connected in parallel to the regenerative hydraulic motor may be omitted, or the stop valve connected upstream of the regenerative hydraulic motor may be omitted. In addition, the throttle and the return oil flow rate calculation means connected in parallel to the regenerative hydraulic motor may be omitted.

  Further, when there are a plurality of sets of the hydraulic actuator, the main control valve and the pressure flow control valve, and only one set of the pressure flow control valves is open, the regenerative hydraulic motor The throttle connected in parallel and the return oil flow rate calculation means may be provided, and the flow rate of oil obtained from the differential pressure before and after the throttle by the return oil flow rate calculation means, From the sum of the oil passage flow rate obtained from the rotational speed of the regenerative hydraulic motor, the flow rates of all return oils flowing downstream of the pressure flow control valve can be obtained. As a result, the flow rates of all return oils can be easily obtained.

DESCRIPTION OF SYMBOLS 1 Hydraulic pump 2 Main control valve 3 Operation part 4 Engine 5 Oil tank 6 Control apparatus 8 Hydraulic actuator 21, 22 Pressure flow control valve 23 Relief valve 33 Restriction 43 Stop valve 57, 59, 60 Oil return line 62 Hydraulic motor for regeneration 63 Generator 64 Inverter 65 Power storage device 66 Return oil flow rate calculation means

Claims (3)

A hydraulic pump (1);
A hydraulic actuator (8) driven by oil discharged from the hydraulic pump (1);
An operation unit (3) for operating a supply amount of discharged oil supplied from the hydraulic pump (1) to the hydraulic actuator (8);
The flow direction of the discharge oil supplied from the hydraulic pump (1) to the hydraulic actuator (8) is switched, the operation direction of the hydraulic actuator (8) is switched, the opening degree is adjusted, and the hydraulic actuator A main control valve (2) for adjusting the speed of (8);
A regenerative hydraulic motor (62) that rotates with return oil from the hydraulic actuator (8);
A generator (63) driven by the regenerative hydraulic motor (62);
Provided in an oil return line (57, 59, 60) connecting the hydraulic actuator (8) and the regenerative hydraulic motor (62), and supplied from the hydraulic actuator (8) to the regenerative hydraulic motor (62). Pressure flow control valves (21, 22) for controlling the pressure and flow rate of the return oil,
A control device (6) for changing the set pressure and set flow rate of the pressure flow control valve (21, 22) based on the magnitude of the operation of the operation unit (3) ,
When the hydraulic actuator (8), the main control valve (2), and the pressure flow control valves (21, 22) are in one set, or
There are a plurality of sets of the hydraulic actuator (8), the main control valve (2), and the pressure flow control valves (21, 22), and one set of the pressure flow control valves (21, 22) of the plurality of sets. ) Is open,
In the oil return line (57, 59, 60) connecting the hydraulic actuator (8) and the regenerative hydraulic motor (62), the regenerative system is located downstream of the pressure flow control valves (21, 22). A throttle (33) connected in parallel to the hydraulic motor (62) for
From the sum of the oil flow rate obtained from the differential pressure before and after the throttle (33) and the oil flow rate obtained from the rotational speed of the regenerative hydraulic motor (62), the pressure flow control valve (21, hybrid hydraulic device, characterized in Rukoto that having a return oil flow rate calculating means (66) for determining the flow rate of all of the return oil flows to the downstream side of the 22). The hybrid hydraulic apparatus according to claim 1, wherein
In the oil return line (57, 59, 60) connecting the hydraulic actuator (8) and the regenerative hydraulic motor (62), the regenerative system is located downstream of the pressure flow control valves (21, 22). A hybrid hydraulic apparatus, wherein a relief valve (23) is connected in parallel to the hydraulic motor (62). The hybrid hydraulic apparatus according to claim 1 or 2 ,
In the oil return line (57, 59, 60) that connects the hydraulic actuator (8) and the regenerative hydraulic motor (62), the regenerative system is located downstream of the pressure flow control valves (21, 22). A hybrid hydraulic apparatus, characterized in that a stop valve (43) is connected upstream of the hydraulic motor (62).

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