JP4902481B2 - Oil pump - Google Patents

Description

  The present invention relates to an oil pump that is applied to a power steering device of an automobile and supplies hydraulic pressure to a power cylinder for steering assist, and more particularly, to an oil pump that changes its discharge amount according to the running state of a vehicle.

  As this type of oil pump, for example, one disclosed in Patent Document 1 has been proposed. The oil pump described in Patent Document 1 is a so-called variable displacement vane pump that uses a vehicle engine as a drive source, and the discharge amount per one rotation of the pump decreases as the engine speed increases. Yes.

  Specifically, the cam ring that houses the rotor with the vane is held by the pump body so as to be movable in a direction in which the amount of eccentricity with the rotor increases or decreases, and a pair of pressures are provided on both sides of the cam ring in the moving direction. A chamber is formed, and the hydraulic pressure in the two pressure chambers is controlled by a spool valve that operates according to the hydraulic pressure on the pump discharge side. In other words, when the engine speed increases, the control valve operates in accordance with the fluid pressure on the pump discharge side, so that the cam ring moves in a direction in which the amount of eccentricity with the rotor decreases, and the pump discharge amount decreases. Become.

In addition, a solenoid is provided on the spool of the spool valve to provide thrust in a direction to increase the eccentric amount between the cam ring and the rotor, and a predetermined energization current corresponding to the running state of the vehicle is provided by electronic control means. Power is supplied to the solenoid. That is, a comfortable steering feeling can be obtained by using electronic control together with the variable displacement vane pump and changing the pump discharge amount in accordance with the running state of the vehicle.
JP 2001-304139 A

  In the technique described in Patent Document 1, the solenoid applies thrust to the spool of the spool valve in a direction to increase the eccentric amount of the cam ring and the rotor. In the unlikely event that power supply to the solenoid is interrupted due to an abnormality, the flow rate of hydraulic fluid supplied to the power cylinder for steering assist becomes small and the steering assist force becomes weak. However, if an excessive current is supplied to the solenoid due to an electrical abnormality of the electronic control means, an excessive thrust is applied to the spool of the spool valve. The flow rate of hydraulic oil supplied to the cylinder is excessive, and the steering assist force suddenly increases, which may cause the driver to turn too much. That.

  The present invention has been made in view of the above-described problems. In particular, when an excessive current is supplied to the solenoid, the power supply to the solenoid is cut off to prevent excessive turning of the rudder. An object of the present invention is to provide an oil pump for a power steering apparatus that is preferable from the viewpoint of safety.

The invention according to claim 1 is an oil pump that supplies hydraulic pressure to a power cylinder for steering assist of a power steering device, and has a control valve that operates in accordance with the hydraulic pressure on the pump discharge side. The discharge amount of the oil pump itself is changed, and the valve body of the control valve is driven by a solenoid in a direction to increase the discharge amount of the oil pump itself . A drive control means for determining whether or not the steering angle exceeds a predetermined value, and calculating a target current value to be supplied to the solenoid in accordance with the traveling state of the vehicle when the steering angle exceeds the predetermined value ; Power supply means for supplying power to the solenoid based on the calculated target current value and power for detecting the actual current value supplied to the solenoid. The drive control means constantly monitors the actual current value detected by the current sensor and the target current value, and the difference between the actual current value and the target current value is a predetermined value. When exceeding, the power supply from the power supply means to the solenoid is cut off.

  In the first aspect of the present invention, the drive control means constantly monitors the actual current value detected by the current sensor and the target current value, and the difference between the actual current value and the target current value exceeds a predetermined value. In this case, the power supply to the solenoid is cut off from the power supply means. Therefore, if an excessive current is supplied to the solenoid due to an electrical abnormality, the power supply to the solenoid is cut off. Accordingly, it is possible to prevent the rudder from being turned too much due to an increase in the steering assist force, which is preferable from the viewpoint of fail-safe.

  FIG. 1 is a block diagram showing a power steering apparatus as a more specific embodiment of the present invention, and FIG. 2 is a cross-sectional view of a main part of the vane pump shown in FIG.

  As shown in FIGS. 1 and 2, a vane pump 1 which is a so-called variable displacement oil pump has a pump cartridge including a rotor 3 with a plurality of vanes 2, a cam ring 4 and an adapter ring 5 formed in a pump body 6. A drive shaft 7 for rotating the rotor 3 is rotatably supported by the pump body 6, and the drive shaft 7 is driven by an unillustrated vehicle engine as a drive source. It will be rotationally driven. The rotor 3 rotates together with the drive shaft 7 counterclockwise in FIG.

  The pump body 6 includes a front body 8 and a rear body 9. The front body 8 has a substantially cup shape with a housing space 6a formed therein, and a rear body 9 is assembled so as to close the opening of the housing space 6a. A pressure plate 10 is stacked on the rotor 3, the cam ring 4, and the adapter ring 5 on the front body 8 side, and the pressure plate 10 is in pressure contact with the rotor 3, the cam ring 4, and the adapter ring 5.

  The cam ring 4 is disposed between the adapter ring 5 fixed in a fitted state on the inner wall of the pump body 6 that forms the accommodating space 6a and the rotor 3, and is a swinging fulcrum that connects the pressure plate 10 and the rear body 9. The pin 11 is positioned and supported so as to be swingable in an eccentric state with respect to the rotor 3. The eccentric amount of the cam ring 4 and the rotor 3 is increased or decreased by the swing of the cam ring 4. The cam ring 4 is biased by a spring 15 in a direction in which the amount of eccentricity with the rotor 3 increases.

  Further, between the cam ring 4 and the adapter ring 5, a first pressure chamber 13 and a second pressure chamber 14 which are separated on both sides in the swing direction of the cam ring 4 by the swing fulcrum pin 11 and the seal member 12 are formed. Has been. In other words, the swing fulcrum pin 11 functions as a shaft support portion and a positioning pin for enabling the cam ring 4 to swing, and also functions as a seal member for separating the pressure chambers 13 and 14. It is like that.

  A plurality of pump chambers 16 partitioned by the vanes 2 are formed between the cam ring 4 and the rotor 3 in the circumferential direction, and each pump chamber 16 increases or decreases its volume as the rotor 3 rotates. The power oil PS for steering assist is drawn through the suction side passage 17 formed in the rear body 9 and sucks the hydraulic oil from the reservoir tank T, and also through the discharge side passage 18 formed in the front body 8. It is designed to supply hydraulic pressure.

  The suction side passage 17 has a substantially crescent-shaped pump chamber side opening 17a that opens to a surface desired in the accommodation space 6a of the rear body 9, and an outer opening 17b that opens to the outside of the pump body 6, The pump chamber side opening 17a is opened in the suction space where the volume of the pump chamber 16 increases with the rotation of the rotor 3 in the accommodation space 6a. On the other hand, the discharge-side passage 18 has a substantially crescent-shaped pump chamber-side opening 18 a that opens to a surface desired in the accommodation space 6 a of the front body 8, and an outer opening 18 b that opens to the outside of the pump body 6. The pump chamber side opening 18a is opened in the discharge space where the volume of the pump chamber 16 decreases as the rotor 3 rotates in the accommodation space 6a. A chamber 18c for pressing the pressure plate 10 against the rear body 9 side is formed in the middle part of the discharge side passage 18.

  A valve hole 19 is formed above the accommodation space 6 a in the front body 8, and a control valve 21 is configured by the valve hole 19 and a spool 20 as a valve body inserted into the valve hole 19. As will be described later, the control valve 21 is driven by the pressure difference on the downstream side of the metering throttle 18d provided in the middle of the discharge side passage 18 and the axial thrust applied by the solenoid 22, The hydraulic pressure in the pressure chambers 13 and 14 is controlled.

  The spool 20 has a first land portion 20a formed at one end portion thereof, and a second land portion 20b formed at an intermediate portion thereof. The high pressure chamber is formed in the valve hole 19 with both the land portions 20a and 20b. 19a is separated from the intermediate pressure chamber 19b and the low pressure chamber 19c.

  The intermediate pressure chamber 19b is formed on one side of the first land portion 20a, and the pressure on the downstream side of the metering restrictor 18d formed in the discharge side passage 18 in the discharge side passage 18 is the first pilot pressure passage. 23. Further, a return spring 24 is disposed in the intermediate pressure chamber 19b, and the return spring 24 biases the spool 20 toward the other side. On the other hand, the high pressure chamber 19a is formed on the other side of the second land portion 20b, and the pressure on the upstream side of the metering restrictor 18d in the discharge side passage 18 is guided by the second pilot pressure passage 25. The low-pressure chamber 19c is formed between the land portions 20a and 20b, and the pump suction pressure is guided by the suction pressure passage 26 branched from the suction side passage 17. That is, the spool 20 operates according to the differential pressure between the high pressure chamber 19a and the intermediate pressure chamber 19b.

  In the state shown in FIG. 1, that is, in the state where the pressure difference between the upstream side and the downstream side of the metering throttle 18d in the discharge side passage 18 is small and the spool 20 is positioned on the other side by the urging force of the return spring 24. The chamber 19c is connected to the first pressure chamber 13 via the first connection passage 27, the intermediate pressure chamber 19b is connected to the second pressure chamber 14 via the second connection passage 28, and the cam ring 4 It is in a position where the amount of eccentricity with the rotor 3 is maximized.

  On the other hand, when the pressure difference between the upstream side and the downstream side of the metering restrictor 18d in the discharge side passage 18 becomes larger than the state shown in FIG. 1, and the spool 20 moves to one side against the urging force of the return spring 24. With the movement, the connection between the second pressure chamber 14 and the intermediate pressure chamber 19b is gradually disconnected, the second pressure chamber 14 is connected to the low pressure chamber 19c, and the first pressure chamber 13 and the low pressure chamber 19c are connected to each other. Is gradually disconnected, and the first pressure chamber 13 is connected to the high pressure chamber 19a. As a result, the cam ring 4 swings against the urging force of the spring 15 and the amount of eccentricity between the cam ring 4 and the rotor 3 decreases, and the pump discharge amount decreases.

  That is, when the engine speed, that is, the rotation speed of the rotor 3 is small, the pressure difference between the metering restrictor 18d and the downstream side in the discharge passage 18 is small, and the eccentric amount between the cam ring 4 and the rotor 3 is large. While the pump discharge amount is relatively large, when the engine speed is large, the pressure difference between the pilot throttle 18d and the downstream side in the discharge side passage 18 increases, and the eccentric amount between the cam ring 4 and the rotor 3 decreases. The pump discharge amount is relatively small.

Further, a relief valve 20c is provided inside the spool 20, and the intermediate pressure chamber 19b and the low pressure chamber 19c can communicate with each other via the relief valve 20c. Incidentally, in the middle of the first pilot pressure passage 23 have pilot diaphragm 23a is provided, et al is, when the relief operation of the relief valve 20c, the pump discharge quantity by lowering the oil pressure in the middle pressure chamber 19b by a pilot diaphragm 23a It is designed to decrease.

  Further, a substantially stepped cylindrical plug member 29 that supports the solenoid 22 is screwed and fixed to one end of the valve hole 19, and the tip of a solenoid rod 22 a that is a movable member of the solenoid 22 is assembled to the spool 20. It faces the tip of the pushed push rod 30. When the solenoid 22 shown in FIG. 1 is in a non-energized state, the solenoid rod 22a faces the push rod 30 at a predetermined interval. However, when the solenoid 22 is energized, the solenoid rod 22a is turned into the spool 20. 1 moves to the side and comes into contact with the push rod 30, and the solenoid 22 applies a thrust in the left direction in FIG. 1 to the spool 20.

  When a thrust is applied to the spool 20 by the solenoid 22, the spool 20 moves to the left in FIG. 1 in accordance with the magnitude of the thrust, and the eccentric amount between the cam ring 4 and the rotor 3 increases to increase the pump discharge amount. It will be. In other words, the spool 20 is driven by the solenoid 22 in the direction of increasing the pump discharge amount, and the so-called engine speed sensitive variable displacement vane pump 1 is used in combination with electronic control so as to correspond to the running state of the vehicle. Thus, the discharge amount of the vane pump 1 is changed.

  The solenoid 22 is electrically connected to a drive circuit 32 as power supply means via a relay 31 as a relay, and the drive circuit 32 supplies power to the solenoid 22 based on a command from the CPU 33 as drive control means. It has become. The drive circuit 32 is connected to a power source 34.

  The CPU 33 has a comparison / determination unit 33a and a target current value calculation unit 33b. The target current value calculation unit 33b detects a steering angle signal from a steering angle sensor 35 that detects a steering angle from a neutral state of a steering wheel (not shown). The vehicle speed signal is input from the vehicle speed sensor 36 for detecting the vehicle speed. The target current value calculation unit 33b calculates a target current value to be supplied to the solenoid 22 based on the steering angle signal and the vehicle speed signal, and outputs the target current value signal to the drive circuit 32 and the comparison determination unit 33a. Become.

  In addition to the target current value signal from the target current value calculation unit 33b, the comparison determination unit 33a inputs an actual current value signal from the current sensor 37 that detects the actual current value that is energized to the solenoid 22, and the target current value Based on the comparison determination result between the value signal and the actual current value signal, a disconnection command signal is output to the relay 31 to disconnect the electrical connection between the drive circuit 32 and the solenoid 22. Further, when the electrical connection between the drive circuit 32 and the solenoid 22 is cut off, a warning lamp 38 which is an alarm means for notifying the driver of the fact is connected to the comparison / determination unit 33a so that the target current value signal Based on the result of comparison with the current value signal, the comparison / determination unit 33a outputs a lighting command signal to the warning lamp 38 which is an alarm means.

  FIG. 3 is a flowchart showing the processing contents of the CPU 33.

  Therefore, in the vane pump 1 configured as described above, as shown in FIG. 3, first, the target current value calculation unit 33b compares the steering angle detected by the steering angle sensor 35 with a predetermined value α (S1). ). As a result, when the steering angle detected by the steering angle sensor 35 exceeds the predetermined value α, the target current value calculator 33b calculates a target current value for energizing the solenoid 22 (S2).

  Specifically, the target current value calculator 33 b calculates a steering speed based on the steering angle signal from the steering angle sensor 35, and calculates the target current value based on the steering speed and the vehicle speed signal from the vehicle speed sensor 36. . Then, the target current value calculation unit 33b outputs the target current value signal to the drive circuit 32 and the comparison determination unit 33a (S3), and the drive circuit 32 supplies power to the solenoid 22 based on the target current value signal.

  FIG. 4 is a graph showing an example of the relationship between the steering angle, the vehicle speed, and the target current value.

  That is, the target current value changes according to the vehicle speed and the steering speed, for example, as shown in FIG. 4, and when the actual current value supplied to the solenoid 22 by the drive circuit 32 increases, the solenoid 22 The thrust for driving 20 increases, the pump discharge amount increases, and the power cylinder PS generates a relatively strong steering assist force. On the other hand, when the actual current value decreases, the thrust for the solenoid 22 to drive the spool 20. Decreases, the pump discharge amount decreases, and the steering assist force generated by the power cylinder PS becomes relatively weak. In other words, by changing the target current value according to the steering speed and the vehicle speed and increasing or decreasing the pump discharge amount, the power cylinder PS generates a required steering assist force according to the steering speed and the vehicle speed, and the vehicle travel state is set. It is set to obtain a comfortable steering feeling.

  When the target current value signal is input to the comparison determination unit 33a, the target current value is larger than the actual current value, and the difference between the actual current value detected by the current sensor and the target current value is predetermined. It is determined whether or not the value β is exceeded (S4). When the target current value is larger than the actual current value and the difference between the actual current value detected by the current sensor and the target current value exceeds a predetermined value β, the comparison determination unit 33a However, an interruption command signal is output to the relay 31 (S5), and the electrical connection between the drive circuit 32 and the solenoid 22 is interrupted. That is, when an excessive current exceeding the target current value is supplied to the solenoid 22 due to an electrical abnormality, power supply from the drive circuit 32 to the solenoid 22 is cut off.

  In addition, the comparison determination unit 33a outputs an alarm signal to the target current value calculation unit 33b. When the target current value calculation unit 33b receives the alarm signal, the target current value calculation unit 33b sets the target current value to 0 (S6). Further, the comparison / determination unit 33 a outputs a lighting command signal to the warning lamp 38 to light the warning lamp 38.

  Therefore, according to the present embodiment, the comparison / determination unit 33a constantly monitors the actual current value detected by the current sensor 37 and the target current value calculated by the target current value calculation unit 33b. When an excessive current exceeding the value is supplied to the solenoid 22, power supply from the drive circuit 32 to the solenoid 22 can be cut off by the relay 31, thereby preventing an excessive turning of the rudder due to an unexpected increase in steering assist force. Therefore, it is preferable from the viewpoint of fail-safe.

  In the unlikely event that an excessive current is supplied to the solenoid 22, the pump discharge amount increases and the power steering device generates more heat, so that the steering force is further reduced due to the rise in hydraulic oil temperature. In addition, there is a problem that the rubber parts used in the power steering device deteriorate, but in this embodiment, when an excessive current exceeding the target current value is supplied to the solenoid 22 due to an electrical abnormality, By shutting off the power supply from the drive circuit 32 to the solenoid 22 by the relay 31, those problems can be solved.

  Furthermore, when the power supply from the drive circuit 32 to the solenoid 22 is interrupted, the warning lamp 38 is turned on, so that there is an advantage that the driver's attention can be drawn and safety can be further improved.

The figure which shows the structure of the power steering apparatus as embodiment of this invention. FIG. 2 is a cross-sectional view of a main part of the vane pump in FIG. 1. The flowchart which shows the processing content of CPU in FIG. The graph which shows the relationship between a steering speed, vehicle speed, and a target electric current value.

Explanation of symbols

1 ... Vane pump (oil pump)
DESCRIPTION OF SYMBOLS 2 ... Vane 3 ... Rotor 4 ... Cam ring 13 ... 1st pressure chamber 14 ... 2nd pressure chamber 18 ... Discharge side channel | path 18d ... Metering throttle 20 ... Spool (valve body)
21 ... Control valve 22 ... Solenoid 31 ... Relay (relay)
32 ... Drive circuit (power supply means)
33 ... CPU (drive control means)
37 ... Current sensor 38 ... Warning light (alarm means)
PS ... Power cylinder

Claims (5)

An oil pump that supplies hydraulic pressure to a power cylinder for steering assist of a power steering device,
It has a control valve that operates according to the hydraulic pressure on the pump discharge side, and the discharge amount of the oil pump itself is changed with the control valve, and the valve body of the control valve is controlled by the solenoid of the oil pump itself. In what is driven in the direction to increase the discharge amount,
Drive control means for determining whether or not the steering angle of the power steering device exceeds a predetermined value, and calculating a target current value to be supplied to the solenoid in accordance with the running state of the vehicle when the predetermined value is exceeded When,
Power supply means for supplying power to the solenoid based on the target current value calculated by the drive control means;
A current sensor for detecting the actual current value energized in the solenoid;
With
The drive control means constantly monitors the actual current value detected by the current sensor and the target current value, and supplies the power when the difference between the actual current value and the target current value exceeds a predetermined value. An oil pump characterized in that power supply from the means to the solenoid is cut off.   The power supply means is electrically connected to a solenoid via a relay, and the drive control means is configured such that the difference between the actual current value detected by the current sensor and the target current value exceeds a predetermined value. 2. The oil pump according to claim 1, wherein a cutoff command signal is output to the relay to cut off an electrical connection between the power supply means and the solenoid.   When the actual current value detected by the current sensor is larger than the target current value and the difference between the actual current value detected by the current sensor and the target current value exceeds a predetermined value The oil pump according to claim 1 or 2, wherein power supply from the power supply means to the solenoid is cut off.   The drive control means notifies that when the difference between the actual current value detected by the current sensor and the target current value exceeds a predetermined value and power supply from the power supply means to the solenoid is cut off. The oil pump according to any one of claims 1 to 3, wherein an alarm means is activated.   A cam ring that houses a rotor with vanes is held movably in a direction in which the amount of eccentricity with the rotor increases or decreases, a pair of pressure chambers are formed on both sides of the moving direction of the cam ring, and the control valve The metering throttle provided in the middle of the discharge side passage of the oil pump is operated according to the pressure difference of the hydraulic oil on the downstream side, and the hydraulic pressure in at least one pressure chamber is controlled by the control valve. The oil pump according to any one of claims 1 to 4, wherein the oil pump is controlled.

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