JPS601392A - Controller for hydraulic pump of variable capacity type - Google Patents

Abstract

PURPOSE:To efficiently use the output power of an engine, by controlling the discharged oil pressure of an engine speed sensor valve depending on the drop in the revolution speed of the engine in a set output power state. CONSTITUTION:When the revolution speed of an engine E decreases below a set reference level Nset, a control unit 20 sends a signal to a proportional solenoid 96 to increase the thrust of an output plunger 97 to reduce the pressure of discharge from an outlet port 93. As a result, the pressure of a third chamber 50 falls, a control piston 36 is moved rightward by a spring 47, and the discharge of a first variable pump P1 is decreased. The torque absorbed by the first variable pump P1 can thus be changed to control the torque of th engine E along a torque curve.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device 1 for controlling a variable displacement hydraulic pump driven by an engine.

Hitherto, glazed type control devices have been proposed as this type of 11〒i control device.

For example, the absorption torque (discharge MX pressure) of a variable displacement hydraulic pump (hereinafter referred to as variable pump) is set to match the rated point of the engine, and the setup torque of the variable pump is always controlled to the cent value. There are known devices that do this.

However, with this control device, as shown in Figure 1, the lifting platform is designed to match the torque characteristics of the engine.
Since the absorption torque of the variable pump is set to match the constant t1 point A of the engine's torque rise, when the engine is under partial load, it becomes parallel to the lateral movement from the rated point A.%'42? The absorption torque of the variable pump is controlled in accordance with the engine output at the intersection of C and each torque curve C.

For this reason, the torque rise of the engine (torque at the diagonal portion in Fig. A''1) cannot be utilized, so the engine output cannot be used effectively in the entire engine speed range.

The present invention has been conceived in consideration of the above-mentioned concerns, and its purpose is to enable effective use of engine output in the area where the engine is completely disconnected.

The present invention will be described in detail below with reference to FIG. 2 and subsequent figures.

Figure 82 is an overall circuit diagram, in which engine E causes the first. The second variable displacement hydraulic pump (hereinafter referred to as the first variable pump) Pl e p and the small-capacity fixed displacement hydraulic pump for control (hereinafter referred to as the control pump) P3 are driven, and the first variable pump The iM'r2.
A third operating valve 21 m 22 m2M is connected in parallel, and a fourth operating valve 21 m 22 m2M is connected in parallel to the discharge passage 3 of the second variable pump h. Fifth. The sixth operation valve No. 2 H2+1126 is connected in parallel, and each edge operation valve 2.
26 are known three-position direct switching valves that supply discharge pressure oil to the first to sixth actuators 41 to 4 such as motors and cylinders.

Said 1st. The capacity control members (hereinafter referred to as swash plates) 5, 6 of the second variable pumps P, , P are controlled by a control mechanism 7.8, and the control mechanisms 7, 8 are connected to the first and second variable pumps p1. ．． Jet sensors l l provided in the drain passages 9 and 10 of the discharge passages 1 and 3 of p.

12 and cut-off pulp 13.14 and K ftJJ
It is controlled by an engine speed sensing pulp 15 provided in the discharge path 16 of the official pump P3.

17 is the fuel injection pump E of the engine E) 0-
19 is a rotation sensor that detects the actual rotational speed of the engine E, and each detected value (signal voltage) is sent to the controller 20. A signal current is transmitted to the engine speed sensing valve 15.

In other words, the set output state of the engine (
For example, maximum output state, medium output state, small output state 'fjM
), this detected value is input to the storage section 20α of the controller 20, and the set reference rotational speed Net t in the set output state is read out from the storage section 20cL and inputted to the calculation section 20b, and the rotation sensor 19 The actual rotational speed N detected in is input to the calculation unit 20b, and when the actual rotational speed N becomes lower than the set reference rotational speed Nsat, a signal current is sent to the engine speed sensing pulp 15 according to the value of (Nεat-N). Send.

In addition, the set reference rotation speed in each set output state)be
t is the rising portion of each torque curve (slightly lower speed flj than the large torque rise portion) as shown in Fig. 4.
) is preferred.

FIG. 2 is a detailed sectional view of each member only on the first variable pump P1 side, and the control device 7 connects the servo piston 31, the input signal section A, and the guide valve section B provided in the case 30 to a+1
1, the servo piston 31 is connected to the swash plate 5 by a rod 32.
A pair of springs 33.33
The swash plate is always held at the minimum angular position (minimum discharge needle position) shown in the drawing, and the pair of springs 33 and 33 are held down by covers 34 and 35.

The input signal section A is provided with a control piston 36, and when the control piston 36 is activated, a first . Second. Third piston 37.
38 and 39 are provided one after another in a straight line, and a fourth piston 40 is provided on the other side.

The guide valve part B has a guide spool 42 inserted into a sleeve 41, and the sleeve 41 is inserted into the case 3°.
A notch 43 is formed that is open across the control piston 36 and the servo piston 31, and the center portion of an arm 44 provided in the notch 43 is pivotally attached to the control piston 36 with a pin 45, and one end 44α is connected to the servo piston. Part 31 of 31 31α
The other end 44A is engaged with the recess 42α of the guide spool 42 through the notch 41α of the sleeve 41.

A rod body 46 is connected to the control piston 36, and the rod body 46 is pushed rightward by a control spring 47 and comes into contact with the first piston 37.
7 forms a first chamber 48 with a stepped portion 37α, the 2Z2 piston 38 forms a second chamber 49 with a stepped portion 38α, and the third piston 39 forms a third chamber 5o with one end surface 39α, An adjustment plug 51 is in contact with one end surface 39α of the third piston 39. 52 is a lock nut.

The fourth piston 40 forms a fourth chamber 53 with a stepped portion 40α, and also has a protruding rod 54 biased and a hook spring 55.
The control piston 36 is biased in a direction away from the control piston 36.

The sleeve 41 has an inlet boat 56 and a first degree second outlet port 59, 5+1! is formed, and the entrance boat 56
is open to the inlet hole 59 of the case 30, and the first. 2nd output) 57.58 is the jth, 22 formed on the case 30.
1st + 2. of the servo piston 31 in the passage 60.61.
The sleeve 41 has a spring seat 64 and a free piston 6 on one end surface.
An adjustment plug 67 screwed into the cap 66 through a free piston 68 is in contact with the other end surface, and an adjustment plug 70 screwed into the cap 69 through a free piston 68 is in contact with the other end surface. 7
1.72 is a lock nut.

The guide spool 42 is formed with an annular groove 73 that connects the inlet boat 56 and the first and second outlet boats 57 and 58.
The servo piston 31 is constantly pushed to the right by a spring 74 to hold the servo piston 31 at the minimum swash plate angle position. Note that the guide spool 42 has a first. 2nd appearance Robo 1-57.
5g through the notch 43. Second annular groove 75
．． 76, and a shaft hole 77 is formed.

The jet sensor 11 has a throttle 82 provided between the inlet boat 80 and the outlet boat 81, detects the total pressure (static pressure + dynamic pressure) through the first port 83, and detects the static pressure through the second boat 84. The 2g1 port 83 is connected to the first chamber 48 through a conduit 85 and a passage 86, and the first piston 37 is moved in the direction beyond the rod body 46 (in the direction of decreasing the discharge amount), and the second The boat 84 is connected to the second chamber 49 through a conduit 87 and a passage 8g to move the second piston 3S toward the first piston 37 (in the direction of increasing the discharge amount).
The first and second pistons 37 and 38 are actuated by the differential pressure between the total pressure and the static pressure due to the flow rate of the drain passage 9.

In other words, as shown in FIGS. 5 and 6, the jet sensor 11 outputs a differential pressure corresponding to the sum of the operating strokes of the first to third operating valves 21 to 2s, and when the differential pressure decreases, The control piston 36 is pushed in the direction of increasing the discharge, and the discharge amount of the first variable pump P1 is controlled according to the differential pressure as shown in FIG.

The engine speed sensing valve 15 has a control spool 9 inserted into the pulp body 90, and a pressure reducing valve and a pressure reducing valve that uses the control spool 91 to pressurize the pressure oil flowing into the inlet port 92 and discharge it to the outlet port 93. The pressure reducing characteristic is determined by the spring 94, and the spring 94
The spring force of 4 can be adjusted with an adjustment plug 95 and is controlled by an output plunger 97 of a proportional electromagnetic trenoid 96.

The inlet boat 92 and the inlet hole 59 are connected to the discharge passage 16 of the control pump P3, and the outlet boat 93 is connected to the third chamber 50 of the third piston 39 through a conduit 98, and is connected to the discharge passage 16 of the control pump P3. An electric signal is sent from the controller 20 to the electromagnetic tunnel 96, and the output plunger 9
7 to the control spool 91.

When the signal current is not sent from the controller 20, the engine speed sensing pulp 15 reduces the discharge pressure of the control pump P to a predetermined pressure, and supplies the same to the third chamber 50 of the third piston 39. controller 2
(1) (According to No. 8 current, the pressure is further reduced from the predetermined pressure and supplied to the third chamber 50, and the control piston 362 is operated in the direction of decreasing the discharge volume.

Here, the current input to the proportional electromagnetic slide/id 96 and the thrust of the output plunger 97 are as shown in FIG. 8, and the thrust and discharge pressure of the output plunger 97 are as shown in FIG.

As a result, the engine rotation speed becomes the set reference rotation speed Ns.
When the pressure decreases below d, the discharge pressure decreases according to the degree of decrease (Nset-N), and the control piston 36 is pushed in the direction of decreasing the discharge amount, and as shown in FIG. 10, the variable pump discharge amount decreases. Decrease.

The cut-off pulp 13 connects a spool 102 (J :'J, this spool 1
02 is always urged to the blocking position by the spring 103, and can be switched to the communicating position by the pressure inside the pressure receiving part 104.
When the pressure in the discharge passage 1 becomes equal to or higher than the one foot value, the pressure in the discharge passage 1 is increased by one pressure to increase the pressure in the 2,1\4 chamber 53 of the side 4 piston 40.
, the fourth piston 40 is pushed to the right against the spring 55, and the control piston 36 is pushed by the protruding rod 54.
is pushed in the direction of decreasing the discharge amount to reduce the discharge amount of the first variable pump P1 by one inch.

The constant pressure at which the spool +02 switches is a very high pressure (slightly lower than the set relief pressure of the main relief valve provided in the discharge path 1) as shown in Figure 1;
As shown in the figure, the discharge of the first variable pump P: the melon is set to the minimum, and the pressure of the discharge passage 1 is set to the maximum.

Next, the details of each part will be explained along with the operation.

When the position of the throttle 18 of the fuel injection pump E1 is set to the medium output state JEit (torque curve I in Fig. M4), and each green valve 2□ to 28 is in the neutral position, the jet sensor? 1
1, the detection difference H: is maximum, the control piston 36 is at the position shown in the figure, and the swash plate 5 is
is set as the minimum tilt angle position, and the discharge amount of the first variable pump P1 is set as the minimum.

That is, the sleeve 41 is in the illustrated position, and the inlet boat 5
6 and 1st. 2nd output robot) 57.58 is shut off and the 1st output robot of the servo piston 31 is shut off. The pressure in the second pressure chamber 62,63 is balanced.

At this time, the rotational speed of engine E is the set reference rotational speed N1
Since the speed is higher than tt, the controller 20 does not output an electric signal and the discharge pressure of the engine speed sensing pulp 15 remains at the set pressure.

When the first operating valve 21 is switched to supply part of the discharge pressure oil of the first variable pump P□ to the 2K I actuator 41, the flow q in the drain passage 9 is reduced, and the differential pressure detected by the jet sensor l+ is reduced. Therefore, as described above, the control piston 36 is pushed to the left, and the arm 44 is pushed to the left with the servo piston 3I as the fulcrum.

The guide spool 42 is moved to the left, and the inlet boat 56 and the second outlet port 58 communicate with each other, so that the pressure oil discharged from the control pump P3 flows into the second pressure chamber 6 of the servo piston 31.
3, and the servo piston 31 (moves to the left to increase the tilt angle of the swash plate 5 and increase the discharge amount of the first variable pump P!).

This causes the arm 44 to move to the pin 45 of the control histone 36.
The guide spool 42 is pushed to the right by the other end 44J, and the entrance boat 56
and the second output robot 5F3 are traced 11fr, and the discharge amount of the first variable pump P increases in accordance with the decrease in the differential pressure detected by the jet sensor 11.

That is, the movement of the servo piston 31 is fed back to the guide spool 42 by the arm 44.

When the engine rotational speed falls below the set standard rotational speed Nsd, the 1B air signal is input from the controller 20 to the proportional electromagnetic solenoid 96 as described above, the thrust of the output plunger 97 increases, and the discharge pressure from the outlet boat 93 increases. is depressurized.

As a result, the pressure in the i13 chamber 5o decreases, and the control piston 36 is moved to the right by the spring 47, and the discharge of the first TrJ variable pump P decreases in the same way as described above.

In other words, when the engine rotation speed decreases below the set standard rotation speed Nset due to an increase in the load acting on the actuator, the discharge Uj f, T of the first variable pump P1 is slightly decreased according to (N5tt - N'), 1.11) By changing (reducing) the torque of the first variable pump P, the torque applied to the engine E can be changed to its torque curve (
Divide by 1 according to b).

At this time, the pressure in the discharge path 1 of the first variable pump P1 increases, but it is lower than the operating pressure of the cutoff pulp +3, so the cutoff pulp 13 is in danger of being broken.

Because of this, the absorption torque of the variable pump can be controlled according to the set engine output condition, and can be controlled along the engine torque curve at that time, so the engine output can be used effectively in the entire engine speed range. .

As described above, the present invention can control the variable displacement D-type hydraulic pump so that the engine output can be effectively utilized in the entire engine speed range.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a diagram showing the matching state 3 with the engine output in a conventional example, FIG. 2 is an explanatory overall diagram showing an embodiment of the present invention, and FIG. Figure 4 is a diagram showing the matching state with the engine output in the present invention, Figures 3p and 5 are diagrams showing the relationship between the operating valve stroke and the drain passage flow rate, and Figure 6 is the diagram showing the relationship between the operating valve stroke and the drain passage flow rate. This figure shows the relationship between flow rate and jet sensor output differential pressure, Figure 7 shows the relationship between jet sensor output ship pressure and variable pump discharge - bow, and Figure 8 shows proportional electromagnetic solenoid input current and output plunger. Figure 9 is a diagram showing the relationship between output plunger thrust and engine speed sensing pulp output pressure. Figure 10 is the relationship between proportional 1d magnetic solenoid input current and variable pump discharge amount. FIG. 11 is a diagram showing the relationship between variable pump discharge pressure and cut-off pulp output pressure, and FIG. 12 is a diagram showing the relationship between variable pump discharge pressure and variable pump discharge amount. p, , p* are 1 variable displacement pump (hydraulic pump, 4 is actuator, 5 is engine speed sensing pulp. 171 people, Komatsu Ltd. agent, patent attorney, civil engineering, Masaaki Hara, Akira Ben, Hama Moto, Tadashi operating valve operation stroke) Fig. 7 Jet sensor output differential pressure Fig. 8 Relative electromagnetic solenoid 1/noid input terminal output plunger thrust '11th to

Claims (1)

[Claims] A variable displacement hydraulic pump p driven by an engine E,
, p, are supplied to the actuator 4, and the discharge amount of the variable hydraulic pumps P, , A is controlled by the pressure oil discharged from the engine speed sensing pulp 15. l',! The variable volume type is characterized in that the engine speed sensing pulp 15 is packaged so that the pressure of the discharge pressure oil is controlled according to the decrease from the set standard rotational speed in each set output state of the engine. Hydraulic pump control device.