JPH041482A - Controller for variable displacement pump - Google Patents

Abstract

PURPOSE:To reduce the extent of penetration of the outside air as well as to prevent a pumping noise from occurring by controlling the opening of an inlet passage to the maximum with a valve means when such a state that a rise in negative pressure in a suction chamber in the pump inside is foreseen, and then keeping off any unneces sary increase of the negative pressure in the suction chamber. CONSTITUTION:A controller 2 regulates flow of working fluid which has reached a suction circuit 30 from a reservoir 29 and flows into an inlet passage 18, and it is provided with a spool valve 31. At this juncture, at time of engine starting, the maximum value of a command current value is inputted into a coil 45 of a magnetic solenoid 43 in spite of small requested flow rate of an apparatus 27 by a controller 48 according to a signal out of an engine starting detector 47. This input is executed as long as the specified period of time, and for the while pressing force of a spool 33 is increased. Then, the total of spring force of a spring 37 and magnetic force out of a pushrod 46 is made larger than the pressing force of a feedback plunger 39 where pressure in a working pressure circuit 28 is made to work by way of a capacity control pressure circuit 40. With this constitution, the spool 33 is stopped at a position where an opening area becomes maximum, thus opening of the inlet passage 18 is maximized.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a device for controlling the discharge capacity and discharge pressure of a positive displacement pump.

(Prior Art) In order to save pump driving energy, it is preferable to control a variable displacement pump so that it discharges the minimum amount required by the equipment to be operated at the upcoming discharge pressure.

As a control device for the discharge volume and discharge pressure for this purpose, the applicant of the present application has previously proposed a device disclosed in Japanese Patent Application No. 2-8506. This device of Japanese Patent Application No. 2-8506 is designed to control the capacity of a variable displacement pump by adjusting the opening of the suction passage of the pump using a throttle means, and when the pump discharge pressure is input as the capacity control pressure. The throttle means is constituted by a valve means that receives the force caused by this force and a discharge pressure control force in a direction opposite to the force, and controls the opening of the pump suction passage to an opening degree such that these forces are balanced. .

According to the device disclosed in Japanese Patent Application No. 2-8506, the discharge capacity of the pump is controlled, and the discharge pressure is also controlled to match the pump discharge pressure with the required pressure of the equipment to prevent waste of pump driving energy. It is possible to provide a device that is compact and inexpensive.

(Problem to be Solved by the Invention) However, in the above conventional device, the opening degree of the suction passage that guides the working fluid to the suction chamber inside the pump is adjusted by a valve means (for example, a spool valve) that uses the pump discharge pressure as the capacity control pressure. Therefore, when the vehicle is stationary, including when starting the engine, the supply flow rate from the pump consumed by the hydraulic suspension etc. decreases and acts in the direction of closing the valve means, so that negative pressure is generated in the suction chamber. It increases. At this time, especially when the outside temperature is low, the seal that isolates the suction chamber defined inside the pump from the outside air loses its elasticity and its sealing function decreases, making the suction chamber more likely to suck in outside air. A problem arises in that the pump noise increases.

An object of the present invention is to solve the above-mentioned problem by maximizing the opening degree of the suction passage using a valve means when a rise in negative pressure is expected in the suction chamber inside the pump.

(Means for Solving the Problems) For this purpose, the first configuration of the variable displacement pump control device of the present invention is a variable displacement pump that can control the flow rate by controlling the opening of the suction passage with a throttle means. The valve means responds to the discharge pressure of the pump as a capacity control pressure, receives a discharge pressure control force in a direction opposite to this capacity control pressure and responds thereto, and determines the opening degree. In the variable displacement pump including the throttle means, the valve means is controlled so that the opening degree of the suction passage is maximized for a predetermined period after the pump is started, regardless of the discharge pressure of the pump. The second configuration is a variable displacement pump capable of controlling the flow rate by controlling the opening of the suction passage with a throttle means, which responds to the discharge pressure of the pump as a displacement control pressure, and also controls the displacement of the pump. In a variable displacement pump in which the throttling means is constituted by a valve means whose opening degree is determined by receiving a discharge pressure control force in a direction opposite to the control pressure, the temperature of the pump hydraulic oil is detected. Oil temperature detection means is provided, and when the detected oil temperature of the hydraulic oil is below a predetermined value, the valve means is controlled so that the opening degree of the suction passage is maximized, regardless of the discharge pressure of the pump. Furthermore, a third configuration is provided with an oil temperature detection means for detecting the oil temperature of the pump hydraulic oil in the first configuration, and when the detected oil temperature of the hydraulic oil is equal to or lower than a predetermined value, a predetermined period of time after starting the pump is provided. , regardless of the discharge pressure of the pump,
The valve means is controlled so that the degree of opening of the suction passage is maximized.

(Function) According to the first configuration of the present invention, when the vehicle is stationary including when starting the engine, the flow rate supplied from the pump consumed by the hydraulic suspension etc. decreases, and the force that tends to close the valve means is reduced. At that time, the valve means is forcibly operated in the opening direction to maximize the opening of the suction passage that guides the working fluid to the suction chamber, so that the negative pressure in the suction chamber does not increase unnecessarily. Therefore, the intrusion of outside air into the suction chamber from the seal portion that isolates the suction chamber defined inside the pump from the outside air is reduced, and generation of noise in the variable displacement pump can be prevented.

According to the second configuration of the present invention, especially at extremely low temperatures,
In order to reduce the intrusion of outside air into the suction chamber due to the deterioration of the sealing function of the seal portion that isolates the suction chamber from the outside air, the valve means is forcibly operated in the opening direction to maximize the opening degree of the suction passage. Therefore, the same noise prevention effect as above can be obtained.

Furthermore, according to the third configuration of the present invention, the first
Since the control of the first and second configurations is performed at the same time, in addition to the above-mentioned noise prevention effect, the maximum discharge flow rate is achieved even though the sealing function has been recovered by - minutes before the oil temperature reaches the predetermined value by starting the pump. In order to prevent this from happening, the control for maximizing the opening of the suction passage can be stopped to prevent waste of pump drive energy.

(Example) Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows a first embodiment of a control device 2 of the present invention applied to a fixed cylinder type radial piston pump 1. As shown in FIG.

The pump 1 includes a pump housing 3 through which a pump drive shaft 4 passes and is rotatably supported by a bearing 5.6. An eccentric cam 4a is integrally molded on the shaft 4 between these bearings, and this eccentric cam is housed in a suction chamber 7 formed in the pump housing 3. A ring 8 is rotatably fitted on the outer periphery of the eccentric cam 4a, and, for example, ten radial pistons 9 (only one is shown in the drawing) are provided on the outer periphery of the ring 8 at equal intervals in the circumferential direction. . Each of these radial pistons 9
extends in the radial direction of the eccentric cam ring 8 and is slidably fitted into a corresponding fixed cylinder 10 formed in the pump housing 3. The external open end of the fixed cylinder 10 is closed by a plug 11 to define a discharge chamber 12 between the plug 11 and the radial piston 9.

Each radial piston 9 has a bottomed sleeve shape with its end close to the eccentric cam ring 8 closed, and is pressed against the eccentric cam ring 8 by a spring 13. and each radial piston 9
On the peripheral wall of the radial piston, there is a suction chamber 7 during the stroke of the radial piston.
A side boat 14 is formed by disposing it at a position where it appears and retracts inside.

The right end of the pump drive shaft 4 in the drawing is used as a power supply end, and a portion of the pump drive shaft 4 near this end is sealed from the pump housing 3 with a seal 15. The other end of the pump drive shaft 4 is sealed with a seal 17 against a passage member 16 attached to the pump housing 3. The passage member 16 has a suction passage 18 and a discharge passage 19, and the same number of discharge passages 19 as the fixed cylinders 10 are formed. The suction passage 18 is communicated with the suction chamber 7 by a communication boat 20 formed in the pump housing 3, and each discharge passage 19 is connected to the suction chamber 7 through a communication boat 20 formed in the pump housing 3.
It is communicated with the corresponding discharge chamber 12 by a communication boat 21 formed in the.

A delivery valve 22 is provided between the communication boat 21 and the discharge passage 19, and this valve opens when a pressure higher than the valve pressure is supplied from the communication boat 21 to supply working fluid from this boat to the discharge passage 19, and in the opposite direction. It shall be of a type that does not allow any working fluid.

An end cover 23 is attached to the side of the passage member 16 far from the pump housing 3, and in addition to forming one groove 24 communicating with all the discharge passages 19, there is also a discharge boat 25 leading to the groove.
form. The discharge boat 25 is connected to an operating pressure circuit 2, which has an accumulator 26 for accumulating future pressure and a pressure operating device 27 operated by the pressure.

Next, the control device 2 according to the present invention will be explained. This control device 2 adjusts the amount of working fluid that has reached the suction circuit 30 from the 11-saha 29 and flows into the suction passage 18, and includes a spool valve 31 as a valve means. This spool valve is constructed by slidably fitting a spool 33 into a valve body 32, and includes an inlet chamber 34 to which a suction circuit 30 is connected to the valve body 32;
and an outlet chamber 35 that communicates with the suction passage 18. The spool 33 provides a variable throttle 36 between the inlet chamber 34 and the outlet chamber 35 whose opening degree changes depending on the stroke of the spool 33 . At the right end of the spool 33 in the figure is a variable aperture 36.
The spring 37 biasing the free piston 3 in the direction of increasing the opening
The other end of the spool 33 is abutted against the feed pump plunger 39, and the pump discharge pressure in the operating pressure circuit 28 is caused to act as a displacement control pressure through the circuit 40.

The valve body 32 is further formed with a fixed orifice 41 that bypasses the variable throttle 36 and short-circuits between the inlet chamber 34 and the outlet chamber 35, and a fixed orifice 61 that short-circuits between the inlet chamber 34 and the chamber 49. This fixed orifice 61
The chamber 49 is kept in an unpressurized state so as not to disturb the stroke of the spool 33, and as a result, no fluctuating pressure is input into the chamber 49, which causes the spool 33 to become unstable and cause the variable throttle 36 to change its opening degree. can be avoided.

The spring 37 is housed in a chamber 42 separated from the outlet chamber 35 by a free piston 38, and a volume change compensation path 51 is formed in the valve body 32 that communicates between this chamber 42 and the inlet chamber 34. 51 and the chamber 35.42 via the fixed orifice 51 allows the free piston 38 to freely stroke.

An electromagnetic solenoid 43 as an electromagnetic means is coaxially provided on the opposite side of the spool valve 31 with the free piston 38 interposed therebetween. The second magnetic solenoid 43 includes a case 44 screwed onto the spool valve body 32, and a coil 45 is housed in the case 44. Then, a slidable bushing rod 46 that passes through the center of the coil 45 and receives electromagnetic force to the left in the figure according to the amount of current applied thereto is brought into contact with the free piston 38.

The amount of current applied to the coil 45 is controlled by the controller 48 based on information from the engine start detection device 47, and
! The amount of electricity is calculated by adding the operating pressure upper limit value of the device 27 (if there are multiple pressure-operated devices 27, the highest operating pressure upper limit value among them) or the pressure loss due to piping resistance other than when starting the engine. When starting the engine, the opening degree of the variable throttle 360 is fixed at a value that maximizes (fully opens) for a predetermined period of time after starting the engine, in accordance with the discharge pressure.

The operation of the above embodiment will be explained next.

The pump drive shaft 4 is rotated by the power supplied thereto, and the eccentric cam 4a integrated with the shaft 4 reciprocates each radial piston 9 within the fixed cylinder 10 via the ring 8. During this reciprocating movement, each radial piston 9 moves toward the side boat 1 in a stroke region far from the axis of the pump drive shaft 4.
4 is closed by the cylinder 0, the working fluid in the discharge chamber 12 is pressurized.

When the working fluid reaches the opening pressure of the delivery valve 22 or higher, it is discharged into the discharge passage 19 while opening the valve 22. The working fluid thus discharged into each passage 19 collects in the groove 24, reaches the working pressure circuit 28 from the discharge boat 25, is accumulated in the accumulator 26, and is used for operating the equipment 27.

- After the side boat 14 opens into the suction chamber 7 during the stroke toward the axis of the pump drive shaft 4, the working fluid in the suction chamber 7 flows into the discharge chamber 12 from the side boat 4. Allow to refill and prepare for the next discharge. At this time, the working fluid in the reservoir 29 is replenished into the suction chamber 7 through the suction circuit 30, the inlet chamber 34, the variable throttle 36, the outlet chamber 35, the suction passage 18, and the communication boat 20.

During the above-mentioned pump operation, the pump discharge flow rate from the boat 25 is controlled in the following manner.

The spool 33 is applied with the pressure in the circuit 28 (pump discharge pressure) via the feedback plunger 39 at the left end in the figure, and the spring force of the spring 37 and the electromagnetic force from the bushing rod 46 (controlled by the controller 48) at the right end in the figure. (determined by the amount of current applied to the coil 45), and the coil 45 stops at a position where the forces on both ends are balanced.

While the pressure-operated device 27 requires a large amount of working fluid for its operation, the pressure in the circuit 28 (pump discharge pressure) decreases. At this time, the spool 31, which is input via the plunger 39 using the pressure in the circuit 28 as a capacity control pressure, moves the spool 33 from the above-mentioned balanced state due to the pressure drop due to the electromagnetic force from the spring 37 and the push port 46. It is moved to the left in the figure and increases the opening of the variable diaphragm 36. Therefore, the working fluid suction limit from the reservoir 29 to the suction chamber 7 becomes large, and the working fluid supply capacity from the official entry chamber 7 to the discharge chamber 12, and therefore the pump discharge flow rate becomes large, which increases the pressure of the pressure-operated equipment 27. It can be matched to your requirements.

On the other hand, when the pressure-operated device 27 does not operate or is in an operating state in which it does not require a small amount of working fluid, the pressure within the circuit 28 (pump discharge pressure) increases, except when starting the engine, which will be described later. At this time, the spool valve 31 moves the spool 33 to the right in the figure due to the pressure increase, and the variable throttle 36
Decrease the opening. Therefore, from the reservoir 29 to the suction chamber 7
The working fluid supply capacity and therefore the pump discharge flow rate are reduced to the required amount required by the pressure-operated equipment 27.

According to the above capacity control, the upper limit of the pump discharge amount, which increases as the pump rotation speed (rotation speed of the shaft 4) increases, is set to the device 2.
Therefore, the pump drive torque can be kept to the minimum necessary and waste of pump drive energy can be prevented.

Note that when the spool 33 makes a full stroke to the right in the figure, the variable throttle 36 is fully closed, but even in this state, the fixed orifice 41 communicates between the inlet chamber 34 and the outlet chamber 35 at a limited opening, and the suction chamber 7 is slightly closed. To compensate for the flow of working fluid to the piston 9, seizing of the piston 9 can be prevented even if the spool 33 is locked in this state.

6' When the engine is started (therefore, when the pump 1 is started), a signal (starting information) is input from the engine start detection device 47 to the controller 48, and in response to this, the controller 48
Even though the required flow rate of the device 27 is small, the maximum command current value is input to the coil 45 of the electromagnetic solenoid 43.

This maximum value input is performed for a predetermined period of time (for example, 30 seconds) after the engine starts, and during that time the pressing force of the spool 330 in the left direction in the figure increases, and the spring force of the spring 37 and the electromagnetic force from the bushing rod 46 increase. Since the sum of the forces increases the pressure of the operating pressure circuit 28 to be greater than the pressing force of the feedback plunger 39 in the right direction in the figure, which is applied via the capacity control pressure circuit 40, the spool 33 stops at the position where the opening area is maximized. The opening of the suction passage is maximized.

As a result, it is possible to suppress the negative pressure inside the suction chamber 7 from increasing unnecessarily, so that the intrusion of outside air into the suction chamber 7 is reduced, and as the aim of the present invention, the generation of noise from the pump 1 is prevented. be able to.

The abdominal pressure M decoy controller 48 instructs the upper limit of the operating pressure of the pressure-operated device 27, and additionally supplies a current to the coil 45 in accordance with this upper limit of the operating pressure. This current is, for example, a current value corresponding to a pressure value obtained by adding the pressure loss due to piping resistance to the upper limit value so that the inside of the operating pressure circuit 28 reaches the above upper limit value.

In other words, when the controller 48 issues a command to increase the upper limit of the operating pressure of the pressure-operated device, the amount of current applied to the coil 45 increases accordingly. At this time, the electromagnetic solenoid 43 increases the electromagnetic force from the bushing rod 46 to the spool 33 in the leftward direction in the figure. As a result, the force due to the pump discharge pressure directed to the right in the figure on the spool 33 and the force due to the magnetic force exerted on the spool 33 by the spring 37 and the magnetic force directed to the left in the figure are balanced by a higher pump discharge pressure, and the pump discharge pressure The pressure can be matched to the upper limit of the operating pressure of the pressure-operated device 27, and it is possible to prevent the pump discharge pressure from becoming excessive with respect to the required pressure and the pump drive energy being wasted.

FIG. 2 is a sectional view similar to FIG. 1 showing a second embodiment of the present invention, and in this embodiment, an oil temperature sensor 71 is provided in the reservoir 29 instead of the engine start detection device 47. This second
In the embodiment, the controller 48 determines the temperature situation based on the input oil temperature information, and when the oil temperature in the reservoir tank is at an extremely low temperature below a predetermined value, the controller 48 determines the temperature status for a predetermined period after the engine start in the first embodiment. Similarly, solenoid 4
The maximum value of the command current is input to the coil 45 of No. 3.

In this way, when the temperature is extremely low, the sealing function of the seal portion that isolates the suction chamber 7 from the outside air decreases, making it easier to suck in outside air, and the degree of opening of the suction passage is maximized. In addition, when the sealing function is in good condition except at extremely low temperatures, the discharge flow rate does not increase even when the engine is started, and waste of pump driving energy can be prevented. can.

FIG. 3 is a sectional view similar to FIG. 1 showing a third embodiment of the present invention, and this embodiment includes an engine start detection device 47 and an oil temperature sensor 71 provided in the reservoir 29. . In this third embodiment, the controller 48 inputs the maximum value of the command current to the coil 45 of the solenoid 43 only during a predetermined period (for example, 30 seconds) after the engine is started and when the temperature is extremely low.

In this way, in the second embodiment, the rate of increase in oil temperature is slow, so even though the oil temperature has actually risen and the sealing function has recovered to a good state, the timing of detecting this is delayed. There is a concern that the discharge flow rate may continue to be undesirably high during this period, but in this example, such a situation does not occur, and waste of pump drive energy during that period can be prevented.

In the second and third embodiments described above, the oil temperature sensor 71 is provided in the reservoir 29, but the sensor installation position is not limited to this, and may be near the seal that isolates the suction chamber from the outside air, or The temperature sensor can be installed in a place where it can detect the temperature conditions in the vehicle (for example, a temperature sensor can be installed inside the vehicle interior or in the cooling water container to detect the temperature inside the vehicle and the temperature of the cooling water). do). Further, in each of the above embodiments, a radial piston pump is used as the variable displacement pump, but the pump is not limited to this, and any variable displacement pump that performs suction and discharge by the action of rotational input may be used. Further, in each of the embodiments described above, the flow rate is controlled by feedback of the discharge pressure, but the invention is not limited to this. For example, the running condition of the vehicle is detected, and based on this detected information, a step motor or the like is used to control the flow rate of the suction passage. The present invention is also applicable to those that control the opening degree of the valve.

(Effects of the Invention) Thus, as described above, the control device for the variable displacement pump of the present invention maximizes the opening degree of the suction passage by means of the valve means when a rise in negative pressure is expected in the suction chamber inside the pump. Since the negative pressure in the suction chamber does not increase unnecessarily and the amount of outside air entering the variable displacement pump is reduced, pump noise can be prevented from occurring.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a radial piston pump showing a first embodiment of the control device of the present invention, FIG. 2 is a cross-sectional view similar to FIG. 1 showing a second embodiment of the present invention, and FIG. FIG. 2 is a sectional view similar to FIG. 1 showing a third embodiment of the present invention. 1...Fixed cylinder type radial piston pump 2...
- Control device of the present invention 4... Pump drive shaft 7...
Suction chamber 8... Eccentric cam ring 9...
Radial piston 10...Fixed cylinder 12...
・Discharge chamber 14...Side port 18・
...Suction passage 19...Discharge passage 22...
・Delivery valve 24...Groove 25...Discharge boat 31...Spool valve (valve means) 33...Spool 34...Inlet chamber 35
...Exit chamber 36...Variable aperture 40.
... Capacity control pressure circuit 43 ... Electromagnetic solenoid (electromagnetic means) 45 ... Coil 47 ... Engine start detection device 48 ... Controller 51 ... Volume change compensation path 71 ... Oil temperature sensor

Claims (1)

[Scope of Claims] 1. A variable displacement pump capable of controlling the flow rate by controlling the opening of the suction passage with a restricting means, which responds to the discharge pressure of the pump as a displacement control pressure and controls the displacement. In a variable displacement pump in which the throttling means is constituted by a valve means whose opening degree is determined by receiving a discharge pressure control force in a direction opposite to the pressure, the pump is operated for a predetermined period after starting the pump. A control device for a variable displacement pump, characterized in that the valve means is controlled so that the opening degree of the suction passage is maximized regardless of the discharge pressure. 2. A variable displacement pump capable of controlling the flow rate by controlling the opening of the suction passage with a restricting means, which responds to the discharge pressure of the pump as a displacement control pressure, and also operates in a direction opposite to this displacement control pressure. In a variable displacement pump in which the throttling means is constituted by a valve means whose opening degree is determined in response to a discharge pressure control force, an oil temperature detection means for detecting the temperature of pump hydraulic oil is provided, When the detected temperature of the hydraulic oil is below a predetermined value, the valve means is controlled so that the opening degree of the suction passage is maximized, regardless of the discharge pressure of the pump. , control device for variable displacement volumetric pumps. 3. In the variable displacement pump control device according to claim 1, an oil temperature detection means for detecting the temperature of the pump hydraulic oil is provided, and when the detected oil temperature of the hydraulic oil is below a predetermined value, the control device after the pump starts. A control device for a variable displacement pump, characterized in that the valve means is controlled so that the opening degree of the suction passage is maximized for a predetermined period of time, regardless of the discharge pressure of the pump.