JP6825448B2 - Power steering device - Google Patents

Description

The present invention relates to a power steering device that assists steering of a steering handle by supplying oil in an oil tank to a steering assist mechanism.

Conventionally, there is known a power steering device that feeds oil in an oil tank to a power cylinder (a part of a steering assist mechanism) and drives the power cylinder by the oil pressure of the oil to assist steering.

For example, Patent Document 1 includes a main pump whose drive source is an engine and a sub-pump whose drive source is a battery, depending on the supply state (for example, pressure or flow rate) of oil supplied by the main pump. A power steering device for switching between a main pump and a sub pump is disclosed. In this power steering device, a detection switch for detecting the oil supply state is provided in the oil flow path between the oil tank and the steering assist mechanism.

JP-A-2005-255001

By the way, in the power steering device of Patent Document 1, instead of the detection switch, a contact switch that turns on / off according to contact / non-contact with the spool of the steering assist mechanism is provided, and the main pump is provided when the contact switch is off. Is driven, and the sub-pump is driven when the contact switch is on.

However, when the amount of oil supplied by the main pump decreases due to damage to the oil pipe, for example, the liquid level of the oil tank drops, air biting occurs, and pulsation of the supplied oil occurs. As a result, in the above configuration, the reciprocating movement of the spool is repeated, the contact switch is frequently turned on and off, and oil may not be supplied to the steering assist mechanism.

An object of the present invention is to provide a power steering device capable of supplying oil to a steering assist mechanism even when oil pulsation occurs.

The power steering device of the present invention includes a main pump driven by a first drive source and a sub-pump driven by a second drive source, and the main pump and the main pump according to an oil feeding state by the main pump. A power steering device that switches between the sub-pump and feeds the oil in the oil tank to the steering assist mechanism by one of the pumps to assist the steering of the steering handle, and is the oil supplied by the main pump. A spool that moves to the first position when the pressure or flow rate of is equal to or higher than a predetermined value, and moves to a second position when the pressure or flow rate of the oil supplied by the main pump is less than the predetermined value. A contact switch that turns on when it comes into contact with the spool that has moved to the second position and turns off when it comes into contact with the spool that has moved to the first position, and a control that controls the drive of the sub-pump. The sub-pump is driven when the contact switch is on, and the control unit of the sub-pump when the contact switch is turned off after the drive of the sub-pump is started. Continue driving.

According to the present invention, oil can be supplied to the steering assist mechanism even when oil pulsation occurs.

A side view showing a configuration example of a vehicle equipped with a power steering device according to an embodiment of the present invention. The figure which shows the structural example of the power steering apparatus which concerns on embodiment of this invention. The figure which shows the state which the spool which concerns on embodiment of this invention is in a 1st position. The figure which shows the state which the spool which concerns on embodiment of this invention is in a 2nd position. A flowchart showing an operation example of the power steering device according to the embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a side view showing a configuration example of a vehicle equipped with a power steering device according to an embodiment of the present invention.

The vehicle 1 is, for example, a vehicle such as a tractor or a truck that pulls a trailer, and is provided with a power steering device 10 according to the present embodiment on a front side portion of the vehicle body. The vehicle equipped with the power steering device 10 is not limited to the vehicle 1 shown in FIG. 1, and may be, for example, a four-wheel drive passenger car, or a configuration excluding the power cylinder 13 on the rear side. It may be an ordinary passenger car having only a steering mechanism for the front wheels.

The power steering device 10 includes a power steering unit 12, a power cylinder 13, and a pump unit 14. The power steering unit 12 and the power cylinder 13 may be collectively referred to as a "steering assist mechanism".

The power steering device 10 steers and controls a pair of left and right front wheels 2 provided on the front portion of the vehicle body and a pair of left and right rear wheels 3 provided on the rear portion of the vehicle body.

The power generated by the operation of the steering handle 11 is transmitted to the drag link 2a of the front wheel 2 via the power steering unit 12 and the arm 15a of the link mechanism 15. As a result, the front wheel 2 is steered to the left and right.

Further, the power of the arm 15a is transmitted to the rear driven arm 15c via the connecting rod 15b. The movement of the driven arm 15c is transmitted to the drag link 3a of the rear wheel 3, and the rear wheel 3 is steered to the left and right.

The power steering unit 12 is connected to the pump unit 14 via a feed pipe 16 (main feed flow path 16a, main return flow path 16b, sub feed flow path 16c, sub return flow path 16d shown in FIG. 2 to be described later). doing.

As shown in FIG. 2 described later, the pump unit 14 has a main pump (MP) 142, a sub pump (SP) 145, and the like, and the oil in the oil tanks 141 and 144 is used as the power steering unit 12 depending on the situation. To send to. By supplying this oil, the power steering unit 12 assists in steering the front wheels 2.

Further, the power steering unit 12 is connected to the power cylinder 13 on the rear side via a feed pipe 17 (pipes 17a and 17b shown in FIG. 2 to be described later). The power cylinder 13 receives oil from the feed pipe 17 and assists in steering the rear wheels 3.

Further, the vehicle 1 is provided with a warning lamp 18. The warning lamp 18 lights up when the contact switch 125 shown in FIG. 2 to be described later is turned on (details will be described later) to warn the occupants of the vehicle 1.

Next, the configuration of the power steering device 10 will be described with reference to FIG. FIG. 2 is a diagram showing a configuration example of the power steering device 10. Each arrow shown in FIG. 2 indicates the flow of oil.

The power steering device 10 includes a pump unit 14, a power steering unit 12, and a power cylinder 13.

First, the pump unit 14 will be described.

The pump unit 14 is provided with an oil tank 141, a main pump 142, a main feed flow path 16a, and a main return flow path 16b as main circuits.

The main pump 142 is provided in the middle of the main feed flow path 16a. The main pump 142 is, for example, a mechanical pump driven by an engine (not shown). The main pump 142 sucks up the oil in the oil tank 141 and supplies the oil to the power steering unit 12 via the main feed flow path 16a. In this case, the return oil from the power steering unit 12 is returned to the oil tank 141 via the main return flow path 16b.

Further, the pump unit 14 is provided with an oil tank 144, a sub pump 145, a sub feed flow path 16c, and a sub return flow path 16d as sub circuits.

The oil tank 144 communicates with the oil tank 141 via a communication pipe 149. As a result, the inside of the oil tank 144 and the inside of the oil tank 141 are always maintained at the same pressure.

The sub pump 145 is provided in the middle of the sub feed flow path 16c. The sub-pump 145 is, for example, an electric pump driven by a battery 147 as a drive source. The sub pump 145 sucks up the oil in the oil tank 144, and supplies the oil to the power steering unit 12 via the sub feed flow path 16c. In this case, the return oil from the power steering unit 12 is returned to the oil tank 144 via the sub return flow path 16d.

The battery 147 is connected to an alternator (not shown) and is constantly charged while the engine is running.

The SP drive switch 150 is provided between the battery 147 and the motor (M) 151. The SP drive switch 150 is turned off when the contact switch 125 is off, and is turned on when the contact switch 125 is turned on. The on / off of the contact switch 125 will be described later.

FIG. 2 shows a case where the SP drive switch 150 is off. In this case, since the battery 147 and the motor 151 are not connected, the voltage of the battery 147 is not supplied to the motor 151. On the other hand, when the SP drive switch 150 is turned on, the battery 147 and the motor 151 are connected via the SP drive switch 150, and the voltage of the battery 147 is supplied to the motor 151.

When the SP drive switch 150 is turned on, the motor 151 operates by receiving a voltage supply from the battery 147 to drive the sub pump 145.

The control unit 152 is connected to the contact switch 125, and detects the on / off of the contact switch 125. Further, the control unit 152 is connected to the SP drive switch 150 and controls the SP drive switch 150. The details of this control will be described later.

The pump unit 14 has been described above.

Next, the power steering unit 12 and the power cylinder 13 will be described.

The power steering unit 12 includes a pump switching valve 121, a rotary valve 122, a power cylinder 123, and a cylinder switching valve 124. These are housed in the same housing, for example.

The pump switching valve 121 is connected to the main feed flow path 16a, the main return flow path 16b, the sub feed flow path 16c, and the sub return flow path 16d. Further, the pump switching valve 121 communicates with the rotary valve 122 via the feed flow path 121a and the return flow path 121b.

The pump switching valve 121 has, for example, a spool (also referred to as a spool valve) connected to a coil spring. This spool receives the pressure of oil from the main pump 142 as pilot pressure.

Here, the spool will be described with reference to FIGS. 3 and 4. 3 and 4 are views showing the internal configuration of the pump switching valve 121.

As shown in FIGS. 3 and 4, a contact switch 125, a spool 126, and a coil spring 127 are provided inside the pump switching valve 121. The double-headed arrows shown in FIGS. 3 and 4 indicate the moving direction of the spool 126.

When the pressure or flow rate of the oil supplied by the main pump 142 to the pump switching valve 121 is equal to or higher than a predetermined value, the spool 126 receives a normal pilot pressure, and as shown in FIG. 3, the urging force of the coil spring 127. Moves to the first position against. As a result, the main feed flow path 16a is communicated with the feed flow path 121a, and the main return flow path 16b is communicated with the return flow path 121b.

At this time, as shown in FIG. 3, the contact switch 125 is turned off when it is not in contact with the spool 126. The contact switch 125 outputs an off signal to the control unit 152 and the SP drive switch 150. As a result, as described above, the SP drive switch 150 is turned off, and the sub pump 145 is not driven. Therefore, in this case, the oil is supplied by the main pump 142.

On the other hand, when the pressure or flow rate of the oil supplied by the main pump 142 to the pump switching valve 121 is less than a predetermined value, the pilot pressure received by the spool 126 decreases. Examples of this case include a case where the main feed flow path 16a or the main return flow path 16b is damaged and the amount of oil circulating in the main circuit is reduced due to an oil leak, or the engine is stopped. .. In this case, as shown in FIG. 4, the spool 126 moves to the second position by receiving the urging force of the coil spring 127. As a result, the sub feed flow path 16c is communicated with the feed flow path 121a, and the sub return flow path 16d is communicated with the return flow path 121b.

At this time, as shown in FIG. 4, the contact switch 125 is turned on when it comes into contact with the spool 126. The contact switch 125 outputs an on signal to the control unit 152 and the SP drive switch 150. As a result, as described above, the SP drive switch 150 is turned on and the sub pump 145 is driven. Therefore, in this case, the oil is supplied by the Sabun pump 145.

The spool has been described above.

The rotary valve 122 communicates with the power cylinder 123 via the flow paths 123a and 123b. Further, the rotary valve 122 communicates with the cylinder switching valve 124 via the flow paths 124a and 124b. Although not shown, the rotary valve 122 is mechanically connected to the steering handle 11.

The rotary valve 122 switches the roles (functions) of the flow paths 123a and 123b communicating with the power cylinder 123 according to the rotation direction of the steering handle 11.

For example, when the steering handle 11 rotates in a predetermined direction, the rotary valve 122 functions the flow path 123a as a feed flow path and the flow path 123b as a return flow path. On the other hand, when the steering handle 11 rotates in the opposite direction of the predetermined direction, the rotary valve 122 functions the flow path 123a as a return flow path and the flow path 123b as a feed flow path.

Further, the rotary valve 122 switches the roles (functions) of the flow paths 124a and 124b communicating with the cylinder switching valve 124 according to the rotation direction of the steering handle 11.

For example, when the steering handle 11 rotates in a predetermined direction, the rotary valve 122 functions the flow path 124a as a feed flow path and the flow path 124b as a return flow path. On the other hand, when the steering handle 11 rotates in the opposite direction of the predetermined direction, the rotary valve 122 causes the flow path 124a to function as a return flow path and the flow path 124b to function as a feed flow path.

The power cylinder 123 operates in response to the switching of the flow path by the rotary valve 122 described above, thereby assisting the steering of the front wheel 2 in accordance with the direction of the left and right steering operations of the steering handle 11.

The cylinder switching valve 124 has the same configuration as the pump switching valve 121. That is, the oil pressure from the main pump 142 is received as the pilot pressure via the supply path (not shown), and if the pilot pressure is a normal value, the power cylinder 13 is passed through the pipes 17a and 17b of the feed pipe 17. Supply oil to. Then, when the pilot pressure drops, the cylinder switching valve 124 stops the supply of oil to the power cylinder 13.

When the main circuit is normal, the power cylinder 13 operates in response to the switching of the flow path by the rotary valve 122 described above, so that the rear wheel 3 corresponds to the left and right steering operation directions of the steering handle 11. Provides steering assistance.

Although the cylinder switching valve 124 is included in the power steering unit 12 as an example in FIG. 2, the cylinder switching valve 124 may be provided separately from the power steering unit 12.

The power steering unit 12 and the power cylinder 13 have been described above.

Next, the operation of the power steering device 10 of the present embodiment will be described with reference to FIG. FIG. 5 is a flowchart showing an operation example of the power steering device 10.

First, when the engine is driven, the driving of the main pump 142 is started (step S101).

At this time, for example, it is assumed that the pressure or flow rate of the oil supplied to the pump switching valve 121 is equal to or higher than a predetermined value. In this case, the spool 126 receives normal pilot pressure and moves to the first position shown in FIG.

When the spool 126 moves to the first position, the contact switch 125 is turned off, so that the SP drive switch 150 is also turned off and the sub pump 145 is not driven.

By driving the main pump 142, the oil in the oil tank 141 is sucked up, and the sucked up oil flows through the main feed flow path 16a and is sent to the pump switching valve 121.

In the pump switching valve 121, the spool 126 moves to the first position, so that the main feed flow path 16a and the main return flow path 16b communicate with the rotary valve 122. Then, the oil from the pump switching valve 121 is supplied to the power cylinder 123 via the rotary valve 122. Then, the power cylinder 123 assists the steering of the front wheel 2.

Further, in this case, since the pilot pressure in the cylinder switching valve 124 is also normal, the oil from the pump switching valve 121 is supplied to the power cylinder 13 via the rotary valve 122 and the cylinder switching valve 124. Then, the power cylinder 13 assists the steering of the rear wheel 3.

As described above, by driving the main pump 142, the oil circulates in the main circuit of the pump unit 14, the power steering unit 12, and the power cylinder 13.

After that, for example, it is assumed that the pressure or flow rate of the oil supplied to the pump switching valve 121 becomes less than a predetermined value. In this case, the pilot pressure received by the spool 126 decreases, and the spool 126 moves to the second position shown in FIG.

When the spool 126 moves to the second position, the contact switch 125 is turned on (step S102 / YES). Therefore, the SP drive switch 150 is also turned on, and the drive of the sub pump 145 is started (step S103). Further, when the contact switch 125 is turned on, the warning lamp 18 lights up. At this time, the main pump 142 also continues to be driven.

By driving the sub pump 145, the oil in the oil tank 144 is sucked up, and the sucked up oil is sent to the pump switching valve 121 through the sub feed flow path 16c.

In the pump switching valve 121, the spool 126 moves to the second position, so that the sub feed flow path 16c and the sub return flow path 16d communicate with the rotary valve 122, and the main feed flow path 16a and the main return flow path 16b. Is blocked. That is, the flow path communicating with the rotary valve 122 is switched from the main feed flow path 16a and the main return flow path 16b to the sub feed flow path 16c and the sub return flow path 16d.

By this switching, the oil from the pump switching valve 121 is supplied to the power cylinder 123 via the rotary valve 122. Then, the power cylinder 123 assists the steering of the front wheel 2.

Further, in this case, the cylinder switching valve 124 stops the supply of oil to the power cylinder 13. As a result, the steering assist of the rear wheel 3 is stopped.

As described above, by driving the sub pump 145, the oil circulates in the sub circuit of the pump unit 14 and the power steering unit 12.

After that, for example, it is assumed that the pressure or flow rate of the oil supplied to the pump switching valve 121 exceeds a predetermined value. In this case, the pilot pressure received by the spool 126 returns to normal, and the spool 126 moves to the first position.

When the spool 126 moves to the first position, the contact switch 125 is turned off (step S104 / YES), the main feed flow path 16a and the main return flow path 16b communicate with the rotary valve 122, and the oil is supplied by the main pump 142. , The main circuit of the pump unit 14, the power steering unit 12, and the power cylinder 13 circulate.

Originally, when the contact switch 125 is turned off, the SP drive switch 150 is turned off and the drive of the sub pump 145 is stopped, but here, the control unit 152 continues the drive of the sub pump 145 (step S105). That is, when the contact switch 125 is turned on (step S102 / YES) and then turned off (step S104 / YES), the control unit 152 keeps the SP drive switch 150 on, thereby causing the sub pump 145. When the spool 126 reciprocates between the first position and the second position due to the pulsation of the oil, and the sub feed flow path 16c and the sub return flow path 16d communicate with the rotary valve 122. Allows the oil supply to continue.

Further, the control unit 152 measures the time during which the contact switch 125 is turned off (step S104 / YES) from the time when the contact switch 125 is turned off, and when the measured time exceeds a predetermined time, the control unit 152 drives the sub pump 145. Stop (step S106).

Then, when the engine is stopped (step S107 / YES), the flow ends. If the engine is not stopped (step S107 / NO), the flow returns to step S102.

In the above description, the warning lamp 18 is originally turned off when the contact switch 125 is turned off, but when the contact switch 125 is turned off after the contact switch 125 is turned on, the control unit 152 of the warning lamp 18 is turned off. The lighting may be continued.

As described above, according to the power steering device 10 of the present embodiment, the contact switch 125 is turned off after the contact switch 125 is turned on and the subpump 145 is started to be driven. However, it is characterized in that the drive of the sub pump 145 is continued. As a result, oil can be supplied to the power steering unit 12 and the power cylinder 13 even when oil pulsation occurs in the main feed flow path 16a and the main return flow path 16b.

Further, according to the power steering device 10 of the present embodiment, the time during which the contact switch 125 is turned off is measured from the time when the contact switch 125 is turned off, and when the measured time exceeds a predetermined time, the sub pump 145 is used. It is characterized by stopping the driving of. As a result, when oil pulsation does not occur in the main feed flow path 16a and the main return flow path 16b, and when the pressure or flow rate of the oil supplied to the pump switching valve 121 is equal to or higher than a predetermined value, It is possible to switch from the continuous drive of the sub-pump 145 to the drive of the main pump 142.

In the above embodiment, the case where the main pump 142 is a mechanical pump whose drive source is an engine and the sub pump is an electric pump whose drive source is a battery has been described as an example, but the main pump 142 has been described. Both the sub-pump 145 and the sub-pump 145 may be a pump driven by a battery. Thereby, the power steering device of the present embodiment can also be applied to an electric vehicle.

<Summary of the present invention>
The power steering device of the present invention includes a main pump driven by a first drive source and a sub-pump driven by a second drive source, and the main pump and the main pump according to an oil feeding state by the main pump. A power steering device that switches between the sub-pump and feeds the oil in the oil tank to the steering assist mechanism by one of the pumps to assist the steering of the steering handle, and is the oil supplied by the main pump. A spool that moves to the first position when the pressure or flow rate of is equal to or higher than a predetermined value, and moves to a second position when the pressure or flow rate of the oil supplied by the main pump is less than the predetermined value. A contact switch that turns on when it comes into contact with the spool that has moved to the second position and turns off when it comes into contact with the spool that has moved to the first position, and a control that controls the drive of the sub-pump. The sub-pump is driven when the contact switch is on, and the control unit of the sub-pump when the contact switch is turned off after the drive of the sub-pump is started. Continue driving.

In the power steering device, the control unit measures the time during which the contact switch is turned off from the time when the contact switch is turned off, and when the time exceeds a predetermined time, the drive of the sub pump is stopped. You may let me.

The present invention can be applied to a steering assist device that assists steering of a steering handle by supplying oil to a steering assist mechanism using a pump.

10 Power steering device 11 Steering handle 12 Power steering unit 13 Power cylinder 14 Pump section 16 Feed pipe 17 Feed pipe 18 Warning lamp 121 Pump switching valve 122 Rotary valve 123 Power cylinder 124 Cylinder switching valve 125 Contact switch 126 Spool 127 Cylinder spring 141, 144 Oil tank 142 Main pump 145 Sub pump 147 Battery 150 SP drive switch 151 Motor 152 Control unit

Claims (2)

A main pump driven by a first drive source and a sub-pump driven by a second drive source are provided, and the main pump and the sub-pump are switched according to the oil supply state by the main pump. It is a power steering device that feeds the oil in the oil tank to the steering assist mechanism by a pump to assist the steering of the steering handle.
When the pressure or flow rate of the oil fed by the main pump is equal to or higher than a predetermined value, the oil moves to the first position, and when the pressure or flow rate of the oil fed by the main pump is less than the predetermined value, the first position is reached. A spool that moves to position 2 and
A contact switch that turns on when it comes into contact with the spool that has moved to the second position, and turns off when it comes into contact with the spool that has moved to the first position.
It has a control unit that controls the drive of the sub-pump.
The sub pump
Driven when the contact switch is on,
The control unit
When the contact switch is turned off after the drive of the sub pump is started, the drive of the sub pump is continued.
Power steering device. The control unit
The time during which the off is continued is measured from the time when the contact switch is turned off, and when the time exceeds a predetermined time, the drive of the sub pump is stopped.
The power steering device according to claim 1.

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