JP5792049B2 - Hydraulic control device - Google Patents

Description

  In the present invention, a hydraulic actuator is connected to a hydraulic pump via an open center type direction switching valve, and a negative control throttle is provided on the tank side of the direction switching valve, and the direction switching is performed according to the operation amount of the operating device. The present invention relates to a hydraulic control device that controls the hydraulic pump based on an output from a negative control sensor in a construction machine in which a valve position is variable.

  2. Description of the Related Art Conventionally, a configuration is known in which a negative control pressure is supplied to a pump regulator as a pump control hydraulic pressure when a regulator control valve fails, assuming that the pump discharge amount is controlled by negative control (see, for example, Patent Document 1). .

JP 2005-265062 A (Fig. 3)

  However, in the configuration described in Patent Document 1, the negative control pressure generated by the negative control throttle is configured to be supplied to the pump regulator via the negative control pressure extraction line, so that the negative control pressure extraction line that should be originally unnecessary is failed. It has been revived for safety and cannot be said to be an efficient configuration.

  Accordingly, an object of the present invention is to provide a hydraulic control device that can substantially maintain negative control even during a failure without requiring such a negative control pressure extraction line.

In order to achieve the above object, according to one aspect of the present invention, a hydraulic actuator is connected to a hydraulic pump via an open center type direction switching valve, and a negative control throttle is provided on the tank side of the direction switching valve. In a construction machine in which the position of the directional control valve is varied according to the operation amount of the operating device , based on the first negative control pressure-flow rate table defining the relationship between the output from the negative control sensor and the negative control pressure and flow rate A hydraulic control device for controlling the hydraulic pump based on the flow rate calculated in
The second negative control pressure that defines the relationship between the negative control pressure and the flow rate when the negative control sensor detects an abnormality and calculates the negative control pressure based on the operation amount of the operating device and the discharge pressure of the hydraulic pump. -Calculating the flow rate based on the flow rate table, and switching from the control based on the output from the negative control sensor by the mode selector to the control based on the calculated negative control pressure , instead of the output from the negative control sensor, A hydraulic control apparatus is provided that calculates a control command value for the hydraulic pump based on the calculated negative control pressure.

  According to the present invention, it is possible to obtain a hydraulic control device that can substantially maintain negative control even during a failure without requiring such a negative control pressure extraction line.

It is a figure which shows the structural example of the construction machine 1 which concerns on this invention. It is a figure which shows an example of the hydraulic circuit figure of the hydraulic pump control apparatus 100 mounted in the construction machine 1. FIG. It is a control block diagram which shows an example of the principal part process (hydraulic pump 10L side) implement | achieved by the main controller 54 of a present Example. It is a figure which shows an example of the characteristic of a direction switching valve. It is a figure which shows an example of a negative control pressure-flow rate table. It is a flowchart which shows an example of the abnormality detection method of the negative control pressure sensor 27L.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a diagram illustrating a configuration example of a construction machine 1 according to the present invention. In FIG. 1, a construction machine 1 has an upper swing body 3 mounted on a crawler type lower traveling body 2 via a swing mechanism so as to be rotatable around the X axis. The upper swing body 3 includes a boom 4, an arm 5 and a bucket 6, and a boom cylinder 7, an arm cylinder 8 and a bucket cylinder 9 as hydraulic actuators for driving the boom 4, the arm 5 and the bucket 6, respectively. Is provided. The drilling attachment may be another attachment such as a breaker or a crusher.

  FIG. 2 is a diagram illustrating an example of a hydraulic circuit diagram of the hydraulic pump control device 100 mounted on the construction machine 1. The hydraulic pump control device 100 includes a center bypass pipe line 30L that connects the switching valves 11L, 12L, 13L, and 15L from the two hydraulic pumps 10L and 10R that are driven by an engine or an electric motor, or switching valves 11R, 12R, Pressure oil is circulated to the tank 22 through the center bypass pipe line 30R that communicates 13R, 14R, and 15R. The hydraulic pumps 10L and 10R are variable displacement inclined plate piston pumps, and the discharge amount (cc / rev) per rotation is variable. The discharge pressures P1, P2 of the hydraulic pumps 10L, 10R are detected by pressure sensors 28L, 28R. Output signals from the pressure sensors 28L and 28R are supplied to the main controller 54.

  The switching valves 11L, 12L, 13L, and 15L and the switching valves 11R, 12R, 13R, 14R, and 15R are all open center types. That is, the switching valves 11L, 12L, 13L, and 15L and the switching valves 11R, 12R, 13R, 14R, and 15R are normally hydraulically connected by connecting their bleed-off passages to the center bypass conduits 30L and 30R. The discharge sides of the pumps 10L and 10R are connected to the tank 22.

  The switching valve 11L is a spool valve that switches the flow of pressure oil in order to circulate the pressure oil discharged from the hydraulic pump 10L by the traveling hydraulic motor 42L.

  The switching valve 11 </ b> R is a traveling straight valve, and traveling hydraulic motors 42 </ b> L and 42 </ b> R that drive the lower traveling body 2 and any hydraulic actuator of the upper swing body 3 (e.g., boom cylinder 7, arm cylinder 8, bucket cylinder). 9 or the turning hydraulic motor 44) is operated at the same time, the hydraulic oil is circulated from the hydraulic pump 10L to the left and right traveling hydraulic motors 42L and 42R in order to improve the straight traveling performance of the lower traveling body 2. Therefore, it is a spool valve that switches the flow of pressure oil.

  The switching valve 12L is a spool valve that switches the flow of pressure oil in order to circulate the pressure oil discharged from the hydraulic pump 10L by the turning hydraulic motor 44. The switching valve 12R is a pressure oil discharged from the hydraulic pump 10R. Is a spool valve that switches the flow of pressure oil so that the hydraulic oil is circulated by the traveling hydraulic motor 42R.

  Further, the switching valves 13L and 13R supply pressure oil discharged from the hydraulic pumps 10L and 10R to the boom cylinder 7 and flow the pressure oil to discharge the pressure oil in the boom cylinder 7 to the tank 22, respectively. The switching valve 13R is a spool valve that operates when the boom operating lever of the operating device 26 is operated (hereinafter referred to as “first speed boom switching valve 13R”), and the switching valve 13L. Is a spool valve (hereinafter referred to as “second speed boom switching valve 13L”) for joining the pressure oil discharged from the hydraulic pump 10L when the boom operation lever is operated at a predetermined operation amount or more.

  The switching valve 14 </ b> R is a spool valve for supplying the pressure oil discharged from the hydraulic pump 10 </ b> R to the bucket cylinder 9 and discharging the pressure oil in the bucket cylinder 9 to the tank 22.

  Further, the switching valves 15L and 15R supply pressure oil discharged from the hydraulic pumps 10L and 10R to the arm cylinder 8, respectively, and flow the pressure oil in order to discharge the pressure oil in the arm cylinder 8 to the tank 22. The switching valve 15L is a spool valve that operates when the arm operating lever of the operating device 26 is operated (hereinafter referred to as “first speed arm switching valve 15L”), and the switching valve 15R. Is a spool valve (hereinafter referred to as “second speed arm switching valve 15R”) for joining the pressure oil discharged from the hydraulic pump 10R when the arm operation lever is operated at a predetermined operation amount or more.

  The operation device 26 is an operation device for operating the turning hydraulic motor 44, the traveling hydraulic motors 42L and 42R, the boom 4, the arm 5, and the bucket 6, and includes various levers and pedals (arm operation lever, boom operation). Lever, bucket operation lever, turning operation lever, travel pedal (right), travel pedal (left)). Electric signals representing the operation amounts of various levers and pedals in the operation device 26 are supplied to the main controller 54. The method for detecting the amount of operation of various levers and pedals by the user may be a method for detecting the pilot pressure with a pressure sensor, or a method for detecting the lever angle.

  The center bypass pipes 30L and 30R are respectively provided with negative control throttles 20L and 20R between the switching valves 15L and 15R located on the most downstream side and the tank 22 to restrict the flow of the pressure oil discharged by the hydraulic pumps 10L and 10R. This is a pressure oil pipe for generating a control pressure for the negative control system (hereinafter referred to as “negative control pressure”) upstream of the negative control throttles 20L and 20R. The negative control pressure is detected by negative control pressure sensors 27L and 27R. Output signals of the negative control pressure sensors 27L and 27R are supplied to the main controller 54.

  In the configuration shown in FIG. 2, the negative control pressure upstream of the negative control throttles 20L, 20R, the discharge pressures P1, P2, etc. are detected by the pressure sensors 27L, 27R, 28L, 28R, and the detected negative control pressures, discharge pressures P1, P2, etc. The main controller 54 obtains a target value of the discharge flow rate, and drives the electromagnetic proportional valves 57A and 55A to displace the spool valves 600L and 600R so as to obtain the target value of the discharge flow rate, thereby tilting actuators 41L and 41R. To control. At this time, typically, the main controller 54 decreases the discharge amount of the hydraulic pumps 10L and 10R as the detected negative control pressure increases, and decreases the discharge amount of the hydraulic pumps 10L and 10R as the detected negative control pressure decreases. Try to increase. On the other hand, when the negative control pressure sensors 27L and 27R described later are abnormal, the main controller 54 obtains the target value of the discharge flow rate in a manner described in detail below, and sets the electromagnetic proportional valves 57A and 55A so as to be the target value of the discharge flow rate. The tilt actuators 41L and 41R are controlled by driving to displace the spool valves 600L and 600R.

  As shown in FIG. 2, when any hydraulic actuator in the construction machine 1 is not used (hereinafter referred to as “standby mode”), the hydraulic oil discharged from the hydraulic pumps 10L, 10R is the center bypass pipe line 30L. , 30R to reach the negative control 20L, 20R, and increase the negative control pressure generated upstream of the negative control 20L, 20R.

  At this time, the main controller 54 displaces the spool valves 600L and 600R to the first position and drives the tilt actuators 41L and 41R to reduce the discharge amounts of the hydraulic pumps 10L and 10R. Pressure loss (pumping loss) when passing through the bypass pipes 30L and 30R is suppressed.

  On the other hand, when any hydraulic actuator in the construction machine 1 is used, the pressure oil discharged from the hydraulic pumps 10L, 10R flows into the hydraulic actuator via the switching valve corresponding to the hydraulic actuator, and the negative control throttle 20L, The amount up to 20R is reduced or eliminated, and the negative control pressure generated upstream of the negative control throttles 20L and 20R is reduced.

  At this time, the main controller 54 increases the discharge amount of the hydraulic pumps 10L and 10R, circulates sufficient pressure oil to each hydraulic actuator, and ensures the driving of each actuator.

  With the above-described configuration, the hydraulic pump control device 100 causes wasteful energy consumption in the hydraulic pumps 10L and 10R (pressure oil discharged from the hydraulic pumps 10L and 10R is generated in the center bypass pipes 30L and 30R in the standby mode. In the case of operating various hydraulic actuators while suppressing the pumping loss), necessary and sufficient pressure oil can be supplied to the various hydraulic actuators from the hydraulic pumps 10L and 10R.

  Next, a characteristic control method by the main controller 54 of the present embodiment will be described.

  FIG. 3 is a control block diagram illustrating an example of a main process realized by the main controller 54 of the present embodiment. FIG. 3 relates to the configuration on the hydraulic pump 10L side.

When the negative control pressure sensor 27L is normal, the main controller 54 of the present embodiment substantially uses the detected value of the negative control pressure by the negative control pressure sensor 27L as it is, as shown in block 80, and controls the control amount ( Determine the target flow rate). That is, the detected value of the negative control pressure is calculated in block 80-1 from the negative control pressure _pn (detection value) based on the given negative control pressure-flow rate table. . An example of the negative control pressure-flow rate table will be described later with reference to FIG.

  On the other hand, when an abnormality of the negative control pressure sensor 27L is detected, the main controller 54 performs control according to the block 90 of FIG. Note that there are a variety of abnormality detection methods for the negative control pressure sensor 27L, and an abnormality may be detected by any method (an example will be described later with reference to FIG. 6).

In the block 90, each operation amount of the operation device 26 related to each switching valve 11L, 12L, 13L and 15L arranged in the center bypass pipe line 30L, that is, a travel pedal (left) operation amount LS1, a turning lever operation amount LS2 is provided. The signals representing the boom lever operation amount LS3 and the arm lever operation amount LS4 are input. In addition, a signal representing the discharge pressure p _d of the hydraulic pump 10L (hereinafter simply referred to as “pump discharge pressure p _d ”) is input to the block 90. Incidentally, the pump discharge pressure _{p d} is the detection value of the oil pressure sensor 28L.

The bleed opening data table 90-1 includes bleed opening data tables for the switching valves 11L, 12L, 13L, and 15L arranged in the center bypass conduit 30L. The bleed opening data table may be set based on, for example, a characteristic diagram as shown in FIG. In the example shown in FIG. 4, the characteristic C1 is a curve showing the relationship between the operation amount of the directional control valve (the stroke) and an opening area (bleed opening area) A _b. A characteristic C2 indicates an opening characteristic on the meter-in side of the direction switching valve, and a characteristic C3 indicates an opening characteristic on the meter-out side of the direction switching valve. A table representing the characteristic C1 is prepared for each of the switching valves 11L, 12L, 13L and 15L as a bleed opening data table.

The travel pedal (left) operation amount LS1, the turning lever operation amount LS2, the boom lever operation amount LS3, and the arm lever operation amount LS4 are respectively represented by the opening area Ab in the corresponding bleed opening data table (see FIG. 4) 90-1. is converted to, at block 90-2, the corresponding flow coefficient _{c b} are multiplied, is input to the block 90-5. Based on the fact that the equivalent opening area A _e of the throttles connected in series can be expressed by the following equation, the block 90-5 is a parameter c _e A _e as a whole of each switching valve 11L, 12L, 13L and 15L. Is calculated.

ここで、Ａ_ｉは、各切換弁１１Ｌ、１２Ｌ、１３Ｌ及び１５Ｌのブリード開口面積である。この考えに流量係数を加えると、以下の通りとなる。

Here, A _i is the bleed opening area of each switching valve 11L, 12L, 13L, and 15L. When the flow coefficient is added to this idea, it becomes as follows.

ここで、ｃ_ｉは、各切換弁１１Ｌ、１２Ｌ、１３Ｌ及び１５Ｌの流量係数である。尚、ｉは、方向切換弁の数に対応し、例えば切換弁が１つしか存在しない構成では、シグマを取らない計算式となる（即ち、単に１つの切換弁に係る流量係数ｃ及び開口面積Ａの積が算出されることになる）。

Here, _{c i} is the flow rate coefficient of each switching valve 11L, 12L, 13L and 15L. Note that i corresponds to the number of directional control valves. For example, in a configuration in which only one directional control valve exists, i is a calculation formula that does not take sigma (that is, a flow coefficient c and an opening area related to only one directional control valve). A product of A will be calculated).

The c _e A _e obtained in this way is input to block 90-6. The block 90-6, the _other, A n _{c n} and the pump discharge pressure _{p d} is input. A _n c _n are those multiplied by the flow coefficient _{c n} in the negative control aperture 20L in the opening area _{A n} in negative control diaphragm 20L, inputted from the block 90-3, and 90-4. In block 90-6, the negative control pressure _pn is calculated based on the following equation.

このようにして算出されたネガコン圧ｐ_ｎは、ブロック９０−８に入力される。ブロック９０−８では、所与のネガコン圧−流量テーブル（図５参照）に基づいて、算出されたネガコン圧ｐ_ｎから油圧ポンプ１０Ｌの吐出流量の目標値が算出される。尚、図５に示すネガコン圧−流量テーブルは、ネガコン圧ｐ_ｎが高いときは、吐出流量の目標値が小さくなり、ネガコン圧が低下すると、吐出流量の目標値が大きくなる関係を有する。この関係は、ネガコン圧センサ２７Ｌの正常時と同様であってよい。即ち、ブロック９０−８におけるネガコン圧−流量テーブルは、ブロック８０−１におけるネガコン圧−流量テーブルと同一であってよい。即ち、入力されるネガコン圧ｐ_ｎが、検出値であるか（ブロック８０−１）、算出値（予想値）であるか（ブロック９０−８）の相違だけである。

Negative control pressure p _n calculated in this manner is input to the block 90-8. In block 90-8, a given negative control pressure - based on the flow rate table (see FIG. 5), the target value of the delivery rate of the hydraulic pump 10L are calculated from the negative control pressure p _n calculated. The negative control pressure-flow rate table shown in FIG. 5 has a relationship in which the discharge flow target value decreases when the negative control pressure _pn is high, and the discharge flow target value increases when the negative control pressure decreases. This relationship may be the same as when the negative control pressure sensor 27L is normal. That is, the negative control pressure-flow rate table in block 90-8 may be the same as the negative control pressure-flow rate table in block 80-1. That is, the only difference is whether the input negative pressure _pn is a detected value (block 80-1) or a calculated value (expected value) (block 90-8).

  In addition, the formula 3 is based on the following formulas 4 and 5.

ｐ_ｔは、タンク圧であり、ここではゼロとする。ネガコン圧ｐ_ｎに対しては、所定の上限値ｐ_ｎｍａｘが設定される。上限値ｐ_ｎｍａｘは、リリーフ弁の設定圧に対応してよい。

p _t is a tank pressure, and is zero here. For negative control pressure _{p n,} a predetermined upper limit value _{p nmax} is set. The upper limit value _pnmax may correspond to the set pressure of the relief valve.

  The mode selector 94 switches between a mode when the negative control pressure sensor 27L is normal and a mode when the negative control pressure sensor 27L is abnormal. When the main controller 54 detects an abnormality in the negative control pressure sensor 27L, the main controller 54 switches the mode selector 94 to activate the block 90.

  Although not shown, the maximum flow rate (horsepower control target value) at the time of horsepower control is calculated from the engine speed and the set torque, and this horsepower control target value and the target of the discharge flow rate calculated in the block 90 as described above. The smaller one of the values may be selected as the final target value.

Although FIG. 3 relates to the configuration on the hydraulic pump 10L side, the same may be applied to the hydraulic pump 10R side. That is, in the case of the hydraulic pump 10R side, when the negative control pressure sensor 27R is normal, the detected value of the negative control pressure by the negative control pressure sensor 27R is substantially used as it is, and the control amount (target value of the discharge flow rate) of the hydraulic pump 10R. Is determined. When an abnormality of the negative control pressure sensor 27R is detected, each operation amount of the operation device 26 related to each switching valve 11R, 12R, 13R, 14R and 15R disposed in the center bypass pipe line 30R is input to the block 90. Is done. Further, a signal representing the discharge pressure p _d (pump discharge pressure p _d ) of the hydraulic pump 10R is input to the block 90. And the bleed opening data table 90-1 is provided with the bleed opening data table (refer FIG. 4) of each switching valve 11R, 12R, 13R, 14R, and 15R arrange | positioned at the center bypass pipe line 30R.

  FIG. 6 is a flowchart illustrating an example of an abnormality detection method for the negative control pressure sensor 27L. The processing routine shown in FIG. 6 may be executed by the main controller 54 at predetermined intervals. FIG. 6 shows the abnormality detection method for the negative control pressure sensor 27L, but the same may be applied to the abnormality detection method for the negative control pressure sensor 27R.

  In step 600, it is determined based on each operation amount of the controller device 26 whether or not there is a no-operation state. The no-operation state refers to a state where none of the various levers and pedals of the operation device 26 is operated. If it is in the no operation state, the process proceeds to step 602.

  In step 602, the maximum flow rate is instructed to the hydraulic pump 10L.

  In step 604, it is determined whether or not the negative control pressure (detected value of the negative control pressure sensor 27L) is greater than a predetermined value. The predetermined value may be set corresponding to the lower limit value of the detection value range of the negative control pressure sensor 27L obtained when the hydraulic pump 10L discharges the maximum flow rate when the negative control pressure sensor 27L is normal. When the negative control pressure is larger than the predetermined value, the process proceeds to step 606, and when the negative control pressure is smaller than the predetermined value, the process proceeds to step 608.

  In step 606, it is determined that the negative control pressure sensor 27L is normal. In this case, the mode selector 94 is changed or maintained at the switching position where the normal mode of the negative control pressure sensor 27L is formed.

  In step 608, it is determined that the negative control pressure sensor 27L is abnormal. In this case, the mode selector 94 is changed or maintained at a switching position where a mode when the negative control pressure sensor 27L is abnormal is formed.

  According to the hydraulic control apparatus of the present embodiment described above, the following excellent effects can be obtained, among others.

  As described above, even when an abnormality occurs in the negative control pressure sensors 27L and 27R, the negative control can be continued and operability and energy saving can be ensured. As is generally known, the negative control is compatible with human inertia in that the speed of the hydraulic actuator is low when the load is high and the speed of the hydraulic actuator is high when the load is low. It is. Also, the block 90 shown in FIG. 3 can be realized simply by adding a program to the software. Thereby, fault tolerance can be improved easily.

  The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the present invention. Can be added.

  For example, in the above-described embodiment, the hydraulic circuit having a specific configuration shown in FIG. 2 or the like is used, but the configuration of the hydraulic circuit is various. For example, a part of the hydraulic actuator may be realized by a hydraulic pump driven by an electric motor.

  In the above-described embodiment, as shown in FIG. 3 and the like, the negative control pressure is calculated by a specific calculation method. However, the negative control pressure calculation method may be changed or modified. For example, it is considered that the viscosity of the oil changes due to aging of the oil and that the leakage loss of the hydraulic pumps 10L and 10R increases due to aging of the equipment (the command value may not be realized in this way). The pump discharge pressure multiplied by the discharge pressure adjustment gain may be used.

DESCRIPTION OF SYMBOLS 1 Construction machine 2 Lower traveling body 3 Upper turning body 4 Boom 5 Arm 7 Boom cylinder 8 Arm cylinder 9 Bucket cylinder 10L, 10R Hydraulic pump 11L, 11R Switching valve 12L, 12R Switching valve 13L, 13R Switching valve 14R Switching valve 15L, 15R Switching valve 20L, 20R Negative control throttle 22 Tank 26 Operating device 27L, 27R Negative control pressure sensor 28L, 28R Pressure sensor 30L, 30R Center bypass pipe 41L, 41R Tilt actuator 42L, 42R Traveling hydraulic motor 44 Turning hydraulic motor 54 main Controller 55A, 57A Proportional solenoid valve 100 Hydraulic pump controller

Claims (4)

A hydraulic actuator is connected to the hydraulic pump via an open center type directional switching valve, and a negative control throttle is provided on the tank side of the directional switching valve, and the position of the directional switching valve is set according to the operation amount of the operating device. in the construction machine to be variable, the output from Negakonsensa, first negative control pressure that defines the relationship between the negative control pressure and the flow rate - pressure for controlling the hydraulic pump based on the flow rate calculated based on the flow table A control device,
The second negative control pressure that defines the relationship between the negative control pressure and the flow rate when the negative control sensor detects an abnormality and calculates the negative control pressure based on the operation amount of the operating device and the discharge pressure of the hydraulic pump. -Calculating the flow rate based on the flow rate table, and switching from the control based on the output from the negative control sensor by the mode selector to the control based on the calculated negative control pressure , instead of the output from the negative control sensor, A hydraulic control apparatus that calculates a control command value for the hydraulic pump based on the calculated negative control pressure. Calculating the negative control pressure based on the operation amount of the operation device and the discharge pressure of the hydraulic pump means that a bleed opening data table defining a relationship between the operation amount of the operation device and the bleed opening area of the direction switching valve. Based on the operation amount of the operating device, the bleed opening area is calculated, the calculated bleed opening area, the value obtained by multiplying the opening area in the negative control throttle by the flow coefficient in the negative control throttle, the discharge pressure of the hydraulic pump, The hydraulic control device according to claim 1, comprising calculating the negative control pressure based on A plurality of the direction switching valves are provided,
  The negative control pressure is calculated based on the calculated bleed opening area based on the bleed opening data table set for each of the plurality of directional switching valves. The negative control pressure is calculated based on a multiplication value obtained for each of the plurality of directional control valves by multiplying the calculated bleed opening area by a flow coefficient set for each of the plurality of switching valves. The hydraulic control device according to claim 2, comprising: 4. The hydraulic control device according to claim 1, wherein the first negative control pressure-flow rate table is the same as the second negative control pressure-flow rate table. 5.

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