JP4773883B2 - Control device for work machine - Google Patents

Description

  The present invention relates to a control device for a work machine such as a construction machine.

  FIG. 5 shows a main part of a typical hydraulic circuit for driving the boom cylinder 10 of a hydraulic excavator (work machine) (not shown). Expansion / contraction of the boom cylinder 10 is controlled via the control valve 16 based on the operation of the operation lever 14 by the operator. The control valve 16 corresponds to a portion indicated by a two-dot chain line in the drawing, and in this example, includes two spools 18 and 20.

  The first spool 18 is a two-position / four-port switching valve that switches from the B position to the A position in the figure against the spring 22 when a pilot pressure is applied to the pilot port Pp1. The second spool 20 is a three-position / four-port switching valve. When the pilot pressure is applied to the pilot port Pp3 side, the D position shown in the figure, and when the pilot pressure is applied to the pilot port Pp4, the F position shown in FIG. When pilot pressure is not applied to the pilot ports Pp3 and Pp4, the spring ports 24 and 26 are positioned at the position E in the figure. The pilot pressure applied to the pilot ports Pp1 to Pp4 is generated by a pilot valve (not shown) linked to the movement of the operation lever.

  When the boom cylinder 10 is extended, that is, when the boom (not shown) is raised, pilot pressure is generated in the oil passage 11, so that the first spool 18 is in the A position and the second spool 20 is in the D position. The pressure oil from the hydraulic pumps 30 and 32 is supplied to the bottom side 12 of the boom cylinder 10.

  When the boom cylinder 10 is contracted, that is, when the boom is lowered, pilot pressure is generated in the oil passage 13 by the operation of the operation lever 14, so that the first spool 18 is moved to the B position by the urging force of the spring 22. The two spools 20 are respectively switched to the F position, and the return oil on the bottom side 12 of the boom cylinder 10 is drained through the second spool 20.

  In addition, the code | symbol 36 of a figure has shown the holding valve with the poppet 36A.

  On the other hand, Patent Document 1 discloses a construction machine in which a regenerative circuit is formed on the meter-out side (the bottom side of the boom cylinder) and the regenerative energy of the boom cylinder is recovered by driving the pump motor with return oil. Has been. The outline is shown in FIG.

  Also in the example of FIG. 6, the boom cylinder 10 is extended and contracted by switching the control valve 38 as in the conventional example of FIG. 5.

  In the regenerative circuit A1, the return oil path 42 of the boom cylinder 10 is switched to the regenerative path 42A and the non-regenerative path 42B by the switching valve 40, and when performing excavation work or the like. The regeneration path 42 </ b> A is opened, and the energy of the return oil path 42 is recovered via the pump motor 44 and the generator 46. On the other hand, when performing fine manipulation work or the like, the regeneration path 42A is closed, and operability is emphasized.

  Controlling the flow of the return oil path 42 during regeneration in this way means that the load of the regenerative circuit A1 (regenerative load: in other words, the power that can be regenerated by the generator 46 of the regenerative circuit A1) and the boom cylinder 10 This is because the boom operability including the contraction speed (the boom lowering speed) is greatly affected by the amount or pressure of the return oil.

JP 2003-329012 A

  However, the conventional work machine including the construction machine described in Patent Document 1 requires a separate switching valve 40 for controlling the return oil of the regenerative circuit A1 in addition to the control valve 38, and the apparatus is complicated accordingly. In addition, there is a problem that the cost tends to increase.

  The present invention has been made to solve such a conventional problem, and is a regenerative system for a work machine that has a simple hydraulic circuit for the entire apparatus including a regenerative circuit and also has a fail-safe function. An object is to provide a control device.

The invention, together to extend and contract the driving target of the driving cylinder by switching the control valve that moves in conjunction with the operating lever for operating the driving target such as the boom, during the contraction of the driving cylinder, the return oil a control device for a working machine configured in time Namaka ability by the generator coupled to the hydraulic motor and the hydraulic motor the energy is arranged in a passage communicating the control valve and the tank, the control of the control valve, the operation a pilot pressure generated by operation of the lever, the above-configured to perform in the secondary pressure output capable solenoid valve independent pressing force to the pilot pressure, and by the control valve, the extension and contraction of the drive cylinder in addition to switching, the regeneration amount of the energy of the return oil during contraction of the driving cylinder, capable of controlling Then co , When to perform the regeneration, the spool of the control valve, to a range exceeding the stroke available by the pilot pressure, with the construction of further stroke by the solenoid valve, which has solved the above problems is there.

  In the present invention, a control valve that has basically been basically used only for raising and lowering the boom (switching between expansion and contraction of the drive cylinder) is also used as a return oil control function. However, in this case, if the control valve is simply used to control the oil, both the regenerative control and the boom cylinder contraction control will of course depend on the current spool position of the control valve. It becomes unambiguous, and fine control of both becomes difficult. The problem is that if the spool stroke of the control valve is made long and the spool position in the long stroke is controlled through an expensive solenoid valve having a wide hydraulic pressure generation range and high accuracy of the generated hydraulic pressure, Although there is a possibility that it can be overcome to some extent, it not only contributes to cost reduction, but it also makes it impossible to raise and lower the boom even when the solenoid valve breaks down due to disconnection or other problems May occur.

  Therefore, in the present invention, a configuration is adopted in which the control valve is configured by a pilot pressure generated by operating the operation lever and a secondary pressure of an electromagnetic valve capable of outputting a pressing pressure independent of the pilot pressure. The control valve is controlled by the combination.

  As a result, the spool of the control valve can be basically controlled by operating the operation lever, and the lowering speed of the boom can be finely controlled as in the prior art, and the electromagnetic valve can be effectively used together as necessary, for example, It becomes possible to perform regenerative control of intended characteristics such as increasing the flow rate of return oil and increasing the amount of energy recovered.

Also, even if the solenoid valve is broken due to disconnection or some other cause, it is possible to control the raising and lowering of the boom by the operation of the operation lever as in the past, which is highly safe from the viewpoint of fail-safe . In addition, when regenerative, the spool of the control valve is further stroked by the solenoid valve to a range exceeding the possible stroke by the pilot pressure, further reducing the spool loss. As a result, the energy can be recovered with further enhanced regeneration efficiency.

  Various variations are conceivable for the present invention.

For example, the maximum output pressure of the solenoid valve may be set to be higher than the pilot pressure. Thus, if necessary, the spool of the control valve driven by the pilot pressure can be moved in the opposite direction to the movement of the spool by the pilot pressure, and the degree of freedom of control by the electromagnetic valve can be increased .

  Furthermore, the maximum stroke of the control valve may be made variable using the electromagnetic valve in accordance with the regenerative load during the regeneration. Accordingly, for example, it is possible to prevent regeneration that exceeds the capacity of the regenerative motor or the generator due to the boom descending speed being too fast (the amount of return oil is too large). This is an active use of the fact that the solenoid valve can generate hydraulic pressure independent of the operation of the control lever, and is particularly effective in work machines that are subject to hanging loads, such as cranes and lifting magnets. Function.

  In addition, when this invention is applied to regeneration with a boom with a large energy regeneration rate, the most remarkable effect is obtained. However, the application target is not necessarily limited to the boom, and various types of regeneration are possible. The present invention can be applied to a regenerative device for the drive cylinder of FIG.

  The hydraulic circuit of the whole apparatus including the regenerative circuit is simple, and a control device for a work machine having a fail-safe function can be obtained.

  Hereinafter, an example of a preferred embodiment of a control device for a work machine according to the present invention will be described in detail with reference to the drawings.

  FIG. 4 shows the overall configuration of a hydraulic excavator (work machine) 80 to which the present invention is applied.

  The excavator 80 includes a lower traveling body 82, an upper swing body 84, and a working unit 86.

  The working unit 86 includes a boom 88, an arm 90, and a bucket 92, and protrudes in a cantilevered state from the side of the cab 85 of the upper swing body 84. A boom cylinder 93, an arm cylinder 94, and a bucket cylinder 96 are incorporated in the boom 88, arm 90, and bucket 92 of the working unit 86 as hydraulic cylinders (drive cylinders) that drive the 88, 90, and 92, respectively.

  In the present embodiment, the present invention is particularly applied to the return oil passage (meter-out oil passage) when the boom cylinder 93 incorporated in the boom 88 is contracted. That is, in particular, the control of the control valve 100 when the boom cylinder 93 is contracted can output the pilot pressures Pup and Pdw generated by the operation of the operation lever 102 and the pressing pressure independent of the pilot pressures Pup and Pdw. The secondary pressure Pe of the electromagnetic proportional valve 104 is used. The control valve 100 can control the regenerative amount of return oil when the boom cylinder 93 is contracted, in addition to switching between expansion and contraction of the boom cylinder 93.

  Hereinafter, a specific configuration of the hydraulic circuit will be described in detail.

  Referring to FIG. 1, in this embodiment, when the boom 88 is lowered, that is, when the boom cylinder 93 is contracted, the oil passage 106 of the return oil from the boom cylinder 93 is divided into two oil passages at the branch portion 108. 110 and 112 are divided. One of the divided oil passages 110 is a regenerative circuit RE that leads to the tank 118 via the regenerative motor 114 and the generator 116, and the other oil passage 112 that has been diverted is adjusted to flow through the orifice 120 and then to the tank 118. Led.

  The control valve 100 has first and second two spools 100A and 100B each having a function of a three-position four-port switching valve. In the first spool 100A, pilot pressures Pup and Pdn generated by a pilot valve (not shown) by operation of the operation lever 102 are applied to the raising port Pp1 and the lowering port Pp2 via the oil passages 122 and 124, respectively. In other words, it is configured to be driven only by the pilot pressures Pup and Pdn. As a result, the boom 88 is moved up and down mainly at low speed (first speed).

  On the other hand, the second spool 100B is configured such that the pilot pressure Pup is applied to the raising port Pp3 via the oil passage 126 with respect to the raising operation of the boom 88. Of the pilot pressure Pdn generated by the operation of 102 and the discharge pressure (secondary pressure) Pe of the electromagnetic proportional valve 104, the higher hydraulic pressure Ph is applied to the lowering port Pp4. That is, a check valve 132 is arranged at the joining position of the oil passage 128 where the pilot pressure Pdn is generated and the discharge oil passage 130 of the electromagnetic proportional valve 104, and the check valve 132 causes the pilot pressure Pdn and the discharge pressure Pe of the electromagnetic proportional valve 104 to be Is compared, the hydraulic pressure Ph on the higher pressure side is applied to the lowering port Pp4.

  The three positions A to C and D to F of the first and second spools 100A and 100B schematically show typical states, and do not switch to each position in a step shape. Centering on the neutral positions B and E in the complete block state, it is possible to switch smoothly including the intermediate positions toward the extended positions A and D and the contracted positions C and F. Therefore, by controlling the switching state from the neutral positions B and E to the contracted positions C and F, the return oil flow rate can be controlled.

  In this embodiment, the index for adjusting the flow rate is not only the operation position (pilot pressures Pup, Pdn) of the operation lever 102, but also the oil pressure Pt of the rod side oil passage 105 and the bottom side diversion oil passage 110 of the boom cylinder 93. In addition to referring to the hydraulic pressure Pb, the upper limit of the regeneration amount is set by referring to the load in the inverter circuit (not shown) of the regeneration circuit RE. This will be described in detail later.

  Reference numerals 134A to 134D in FIG. 1 indicate return springs for maintaining the spools 100A and 100B at the neutral positions B and E when no hydraulic pressure is applied to the ports Pp1 to Pp4. Reference numerals 136 and 138 denote first and second hydraulic pumps for causing the boom 88 to be raised (expansion operation of the boom cylinder 93), 140 and 142 are pressure sensors, and 144 is the primary of the electromagnetic proportional valve 104. A hydraulic source that provides pressure. The first hydraulic pump 136 also has a function of supplying pressure oil to the rod side when the boom 88 is lowered.

  Next, the operation of the hydraulic excavator 80 will be described in detail focusing on the regenerative control.

  According to the embodiment of FIG. 1, when the boom cylinder 93 is extended by the raising operation of the operation lever 102 (when the boom 88 is raised), the pilot pressure Pup depends on the movement of the operation lever 102. The voltage is applied to the ports Pp1 and Pp3 of the first and second spools 100A and 100B via 122 and 126, respectively. As a result, the first and second spools 100A and 100B are positioned at the extended positions A and D, respectively, and the pressure oil discharged from the first and second hydraulic pumps 136 and 138 passes through the oil passages 112 and 110, respectively. Then, it joins the oil passage 106 and is supplied to the bottom side of the boom cylinder 93. At this time, the pressure oil existing on the rod side of the boom cylinder 93 is drained to the tank 118 via the oil passage 105, the A position of the first spool 100A, and the oil passage 140. . The boom cylinder 93 extends due to the movement of the pressure oil. In addition, since pressure oil does not flow into the regeneration circuit RE, regeneration is not performed.

  When the operation lever 102 is in a neutral state where it is not operated, the pilot pressures Pup and Pdn are all tank pressures, and no pilot pressure is derived to any of the ports Pp1 to Pp4 of the first and second spools 100A and 100B. Further, the electromagnetic proportional valve 104 does not generate any hydraulic pressure at this time. Accordingly, the first and second spools 100A and 100B are positioned at the neutral positions B and E by the urging force of the return springs 134A to 134D. For this reason, the first and second spools 100A and 100B are all in a blocked state, and all the pressure oils are prevented from moving. Therefore, the boom cylinder 93 maintains the cylinder position at that time. Further, since the regenerative circuit RE is also blocked, regeneration is not performed.

  When the boom cylinder 93 is contracted by the operation of lowering the operation lever 102 (when the boom 88 is lowered), the operation differs depending on whether or not regeneration is performed.

  When regeneration is not performed, that is, when delicate operation such as leveling work is required, for example, the discharge pressure Pe of the electromagnetic proportional valve 104 is set to zero (or a standby pressure less than the pilot pressure Pdn). In this case, the pilot pressure Pdn generated depending on the movement of the lowering operation of the operation lever 102 is applied to the pilot port Pp2 of the first spool 100A, and the second spool is connected via the oil passage 128 and the check valve 132. Applied to the port Pp4 of 100B. Therefore, the first spool 100A is positioned at the contracted position C, and the second spool 100B is positioned at the contracted position F. As a result, the pressure oil discharged from the first and second hydraulic pumps 136 and 138 is supplied to the rod side of the boom cylinder 93 via the contracted position C of the first spool 100A and the oil passage 105, and the boom cylinder 93 is also supplied. The pressure oil that was present on the bottom side is discharged to the oil passage 106 side, and the boom cylinder 93 contracts. Note that the pressure oil that has been diverted from the oil passage 106 to the oil passage 110 side rotates the regenerative motor 114 via the contracted position F of the second spool 100B, and drives the generator 116, but is almost no-load operation. Electricity is not regenerated. On the other hand, the flow rate of the pressure oil divided from the oil passage 106 toward the oil passage 112 is controlled through the contracted position C of the first spool 100A, and reaches the tank 118 through the oil passage 140.

  On the other hand, when large energy regeneration can be expected in excavation work or the like, a large discharge pressure Pe exceeding the pilot pressure Pdn is generated by the electromagnetic proportional valve 104. As a result, the discharge pressure Pe of the electromagnetic proportional valve 104 is selected as the output pressure Ph of the check valve 132, and the discharge pressure Pe is applied to the lowering port Pp4. As a result, the second spool 100B is displaced to a contracted position Fm (not shown) obtained with a larger stroke than the contracted position F obtained with the stroke by the pilot pressure Pdn (not shown), and is very large. The pressure oil on the bottom side of the boom cylinder 93 is supplied to the regenerative motor 114 side by the opening (with an extremely small loss). When the regenerative motor 114 rotates, the generator 116 connected to the regenerative motor 114 starts generating power, and regenerative power is accumulated in the battery via an inverter circuit (not shown).

  As shown in FIG. 2, since the generation range of the discharge pressure Pe of the electromagnetic proportional valve 104 is larger than the generation range of the pilot pressure Pdn, the positioning of the contraction positions F to Fm of the second spool 100B is determined by the electromagnetic proportional valve 104. Therefore, the regenerative control can be performed with arbitrary characteristics.

  The specific index used to position the contraction positions F to Fm is not particularly limited, but in this embodiment, the rod side of the boom cylinder 93 in the oil passage 105 is not limited. Are detected by pressure sensors 140 and 142, respectively, and are used as indices for positioning control of the second spool 100B. Qualitatively, the stroke of the second spool 100B is increased as the absolute pressure of the hydraulic pressure Pb is larger, and as the differential pressure (Pt−Pb) between the hydraulic pressures Pt and Pb is larger. To reduce loss and increase regenerative energy.

  However, for example, when the holding pressure is high and the hydraulic pressure Pb in the branch oil passage 110 is very large, the power generation capacity of the generator 116 can be obtained by directing the pressure oil in the branch oil passage 110 to the regenerative circuit RE side as it is. This may cause a problem in durability. Therefore, such an overload state is detected by, for example, the control board of the inverter circuit of the regenerative circuit RE, and the stroke of the second spool 100B is set to an appropriate range by suppressing the discharge pressure Pe at the electromagnetic proportional valve 104. The second spool 100B generates a corresponding pressure loss to limit the torque generated by the regenerative motor 114. The detection of the overload may be indirectly obtained from the output values (Pt, Pb) of the pressure sensors 140 and 142, for example. By performing such limiter control, regeneration close to the power generation limit of the generator 116 can be efficiently performed while avoiding a decrease in durability of the generator 116 due to overload.

  Since the electromagnetic proportional valve 104 generates the discharge pressure Pe based on a command from the electrical system, troubles due to disconnection or other causes are more likely to occur compared to a pure hydraulic system device. However, in the present embodiment, even if some trouble occurs in the electromagnetic proportional valve 104, the regenerative control is not possible, and the raising / lowering control of the boom 88 is performed in the same manner as in the past by operating the operation lever 102. It can be carried out. One of the major features of this embodiment is that such a fail-safe function is compatible with regenerative control using the electromagnetic proportional valve 104 that can generate an arbitrary discharge pressure Pe.

  FIG. 3 shows another embodiment of the present invention. In the previous embodiment, the hydraulic pressure Ph applied to the lowering port Pp4 of the second spool 100B of the control valve 100 is the higher of the pilot pressure Pdn and the discharge pressure Pe of the electromagnetic proportional valve 104 due to the function of the check valve 132. It was configured to be better. However, in the present embodiment, both the pilot pressure Pdn and the discharge pressure Pe2 of the electromagnetic proportional valve 204 are directly applied from the two ports Pp4A and Pp4B of the second spool 100B as the control pressure in the lowering direction of the second spool 100B, respectively. I am doing so.

  According to this embodiment, not only the check valve 132 in the previous embodiment can be omitted, but also the pilot pressure Pdn and the discharge pressure Pe2 of the electromagnetic proportional valve 204 can be utilized as the control pressure in the lowering direction. Therefore, even when an electromagnetic proportional valve smaller than 104 is used as the electromagnetic proportional valve in the previous embodiment as the electromagnetic proportional valve 204, a total pressing force exceeding the spool pressing force that can be generated only by the pilot pressure Pdn is obtained. Can do. Therefore, the discharge pressure Pe2 of the electromagnetic proportional valve 204 does not necessarily need to be larger than the pilot pressure Pdn, and the cost of the electromagnetic proportional valve 204 can be reduced. The positioning of the second spool 100B that governs the regeneration control can be performed very finely by the pilot pressure Pdn generated by the operation of the operation lever 102 and the arbitrary discharge pressure Pe2 generated by the electromagnetic proportional valve 204. Also in the embodiment, both limiter control for preventing overload and boom raising / lowering control (fail-safe control) using only the operation lever 102 when the electromagnetic proportional valve 204 fails are realized in the same manner as in the previous embodiment. be able to.

  Since the other configuration is basically the same as that of the previous embodiment, the same reference numerals are assigned to the same (or similar) parts in the drawing, and the duplicate description is omitted.

  In the above embodiment, in the non-regenerative region, the pilot pressure generated by the movement of the operation lever 102 is used as it is, and the electromagnetic proportional valves 104 and 204 are not particularly functioning. In the non-regenerative region, the electromagnetic proportional valves 104 and 204 may be appropriately functioned to perform finer return oil flow rate control (boom 88 lowering operation control) according to the operation status. .

  Further, in the above embodiment, the control valve has two spools, and the discharge pressure of the electromagnetic proportional valve is applied only to one (second) spool, but in the present invention, It is not always essential that the control valve has two spools. The control valve may be one or may be separated into three or more spools. In the case where the spool is separated into three or more spools, the electromagnetic proportional valve does not necessarily have to be related to driving of all the spools, as in the above-described embodiment.

  The present invention can be particularly effectively applied to a regenerative device for a work machine that includes a working unit having a boom and can drive the boom by extending and contracting a boom cylinder. However, the present invention need not dare to limit the application target to only the regeneration of the boom cylinder, but can be applied to various drive cylinder regenerative devices capable of regeneration, and corresponding effects can be obtained.

The skeleton figure which shows the principal part structure of an example of embodiment of the control apparatus of the working machine which concerns on this invention Graph showing the relationship between pilot pressure and discharge pressure of proportional solenoid valve FIG. 1 is a skeleton diagram showing the configuration of the main part of another embodiment of the present invention. The front view which shows the whole structure of the hydraulic shovel (work machine) to which this invention was applied Skeleton diagram showing the main configuration of a conventional hydraulic circuit for driving a typical boom Skeleton diagram showing the main configuration of a hydraulic circuit capable of conventional regenerative control

Explanation of symbols

80 ... Hydraulic excavator (work machine)
88 ... Boom 93 ... Boom cylinder 100 ... Control valve 100A ... First spool 102B ... Second spool 102 ... Control lever 104 ... Electromagnetic proportional valve 114 ... Hydraulic motor 116 ... Generator 118 ... Tank 120 ... Orifice 130 ... Check valve 134A- 134D ... Return spring
DESCRIPTION OF SYMBOLS 136 ... 1st hydraulic pump 138 ... 2nd hydraulic pump 140, 142 ... Pressure sensor Pp1-Pp4 ... Port RE ... Regenerative circuit

Claims (4)

Together to extend and contract the driving target of the driving cylinder by switching the control valve that moves in conjunction with the operating lever for operating the driving target boom such as when the contraction of the driving cylinder, the control energy of the return oil a control device for a working machine configured in time Namaka ability by the generator which is connected to the hydraulic motor disposed in the passage communicating the valve and the tank to the hydraulic motor,
The control of the control valve, and the pilot pressure generated by operation of the operation lever, wherein the pilot pressure is configured to perform in the secondary pressure output capable solenoid valve independent pressing force, and
By the control valve, in addition to switching of extension and contraction of the driving cylinder, the regeneration amount of the energy of the return oil during contraction of the driving cylinder, the controllably constituting,
The control device for a working machine , wherein when performing the regeneration, the solenoid valve further strokes the spool of the control valve to a range exceeding the stroke possible by the pilot pressure . In claim 1,
A control device for a work machine, wherein a maximum output pressure of the solenoid valve is higher than the pilot pressure. In claim 1 or 2 ,
A control device for a work machine, wherein the maximum stroke of the control valve is made variable using the electromagnetic valve in accordance with a regenerative load during the regeneration. In any one of Claims 1-3 ,
The control valve for a work machine, wherein the control valve has two or more spools, and the secondary pressure of the electromagnetic valve can be applied only to some of the spools.

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