JP2024044933A - Cylinder Unit - Google Patents

Abstract

[Problem] The present invention aims to provide a cylinder device that can improve regenerative power and perform regeneration efficiently. [Solution] The cylinder device A of the present invention includes a hydraulic cylinder 1 having a cylinder 2, a piston 3 that is movably inserted into the cylinder 2 and divides the inside of the cylinder 2 into two working chambers R1, R2, a first flow path 4 and a second flow path 5 that are parallel to each other and communicate the working chambers R1, R2, a first variable throttle valve 6 provided in the first flow path 4, a second variable throttle valve 7 provided in series in the second flow path 5, and a bidirectional discharge pump 9 driven by a motor 8, and a controller 11 that controls the first variable throttle valve 6 and the motor 8, and when the motor 8 is in a braking state, the controller 11 controls the throttle coefficient of the first variable throttle valve 6 so as to increase the rotation speed of the motor 8. [Selected Figure] Figure 1

Description

The present invention relates to a cylinder device.

A conventional cylinder device is, for example, applied to an active suspension interposed between the body and axle of a vehicle, and is specifically configured to include a cylinder, a piston movably inserted into the cylinder to divide the inside of the cylinder into two working chambers, a rod connected to the piston, a first flow path and a second flow path that connect the two working chambers in parallel, a first variable throttle valve provided in the first flow path, a second variable throttle valve and a bidirectional discharge pump provided in series in the second flow path, a hydraulic cylinder having a motor that drives the pump, and a control device that controls the first variable throttle valve, the second variable throttle valve, and the motor (for example, see Patent Document 1).

When a conventional cylinder device is used as an active suspension, the cylinder is connected to one of the vehicle body and the axle, and the rod is connected to the other of the vehicle body and the axle. The pump is driven by a motor to generate thrust, thereby suppressing vibration of the vehicle body.

Furthermore, in conventional cylinder devices, when the hydraulic cylinder is forcibly expanded or contracted by an external force, the pump is rotated by the hydraulic oil flowing through the second flow path, so the motor is used in the braking area to generate and regenerate electric power. occurs. When the motor is thus used in a braking region, the pump provides resistance to the flow of hydraulic oil due to the torque generated by the motor. Therefore, a thrust force is generated in the hydraulic cylinder that prevents the hydraulic cylinder from expanding and contracting due to external force.

Japanese Patent Application Publication No. 2009-196597

In the conventional cylinder device, by adjusting the throttling coefficient of the first variable throttle valve and the throttling coefficient of the second variable throttle valve, the amount of hydraulic fluid passing through the pump and the torque borne by the motor can be adjusted. Note that the throttling coefficient is a value obtained by dividing the flow rate per unit time by the pressure, and indicates that the smaller the throttling coefficient, the greater the resistance in the variable throttle valve.

When the motor is in a braking state, on a graph with motor torque on the vertical axis and motor rotation speed on the horizontal axis, the regenerative efficiency is maximized when the intersection (motor operating point) of the torque output by the motor and the motor rotation speed is on a straight line (maximum regenerative efficiency line) that passes through the origin and is tangent to the short-circuit curve that shows the relationship between torque and rotation speed when the motor is short-circuited.

Therefore, in the conventional cylinder device, when the motor is in a braking state, the first variable throttle valve is adjusted so that the intersection of the torque output by the motor and the rotational speed of the motor is located on the straight line with maximum regeneration efficiency. The throttle coefficient and the throttle coefficient in the second variable throttle valve are adjusted.

In this way, conventional cylinder devices aim to maximize the regenerative efficiency of the motor when it is in a braking state, but the maximum regenerative efficiency line is a line that maximizes the regenerative efficiency in the power consumption characteristics at the same rotation speed, and does not take into account the magnitude of the regenerative power in the power consumption characteristics at the same torque of the motor. Therefore, when the operating point of the motor is within the braking region, guiding the operating point onto the maximum regenerative efficiency line may actually result in a decrease in regenerative power.

Therefore, the present invention aims to provide a cylinder device that can improve regenerative power and perform regeneration efficiently.

In order to achieve the above object, the cylinder device in the problem-solving means of the present invention includes a hydraulic cylinder having a cylinder, a piston movably inserted into the cylinder to divide the inside of the cylinder into two working chambers, a first flow path and a second flow path that are parallel to each other and communicate the working chambers, a first variable throttle valve provided in the first flow path, and a bidirectional discharge pump provided in the second flow path and driven by a motor, and a controller that controls the first variable throttle valve and the motor, and when the motor is in a braking state, the controller controls the throttle coefficient of the first variable throttle valve so as to increase the rotation speed of the motor. With the cylinder device configured in this way, when the motor is in a state where it can regenerate power, the throttle coefficient of the first variable throttle valve is controlled to increase the rotation speed of the motor, so that the power regenerated by the motor can be increased and regeneration can be performed more efficiently than with conventional cylinder devices.

The controller in the cylinder device also includes a first filter that removes a component higher than the unsprung resonance frequency of the vehicle from the rotational speed of the motor, and a second filter that removes a component higher than the unsprung resonance frequency of the vehicle from the motor torque. , a braking state determination unit that determines whether the motor is in a braking state based on the filtered rotational speed processed by the first filter and the filtered torque processed by the second filter; The vehicle may also include a throttle coefficient calculation unit that sets the throttle coefficient of the first variable throttle valve to the braking throttle coefficient when the determination result of the determination unit is a braking determination. According to the cylinder device configured in this way, components higher than the high-frequency unsprung resonance frequency are removed from the rotational speed and torque of the motor, so the braking state of the motor can be accurately controlled in accordance with the vibrations of the sprung members in the vehicle. This makes it possible to understand the situation better and to appropriately control the throttling coefficient of the first variable throttle valve.

Furthermore, the controller in the cylinder device includes a rotational acceleration calculation unit that calculates the rotational acceleration of the motor based on the rotational speed after filter processing, and the aperture coefficient calculation unit is configured to determine that the determination result of the braking state determination unit is power running; When the operating point of the motor is in the first quadrant, the rotational acceleration is less than 0, and the absolute value of the rotational acceleration is greater than or equal to the threshold, and when the operating point of the motor is in the third quadrant, and the rotational acceleration is greater than or equal to 0. If the absolute value of the rotational acceleration is equal to or greater than the threshold value, the target throttle coefficient of the first variable throttle valve may be set so as to gradually decrease the flow path of the first variable throttle valve. According to the cylinder device configured in this way, when the motor is about to transition to the braking state, a gradual reduction process is performed to gradually reduce the throttling coefficient of the first variable throttle valve from when it is in the power running state, so that the motor is not in the braking state. When the state changes, the throttling coefficient of the first variable throttle valve is changed so as to increase the regenerative power of the motor, thereby making it possible to efficiently improve the regenerative power.

Further, the controller in the cylinder device includes a torque estimating section that estimates a zero cross torque that is the torque when the rotational speed becomes 0 when the motor transitions from the powering state to the braking state, and the aperture coefficient calculating section includes: A braking throttle coefficient that increases the regenerative power of the motor may be determined from the zero cross torque, and a target throttle coefficient of the first variable throttle valve may be determined based on the braking throttle coefficient. According to the cylinder device configured in this way, the throttling coefficient during braking is calculated backward from the zero cross torque of the motor and set to a value that does not change the actual thrust of the hydraulic cylinder when the rotational speed of the motor becomes 0. Therefore, even if the motor is in a braking state and the regenerative power is controlled to be increased, fluctuations in the actual thrust of the hydraulic cylinder can be suppressed.

Furthermore, the throttle coefficient calculation unit in the cylinder device may gradually increase the throttle coefficient of the first variable throttle valve to an initial value that increases the flow path larger than the throttle coefficient during braking when the braking state determination unit transitions from a braking determination to a powering determination. With this cylinder device configured in this way, when the motor transitions from a braking state to a powering state, a gradual increase process is performed to gradually increase the throttle coefficient of the first variable throttle valve to an initial value suitable for controlling the thrust of the hydraulic cylinder when the motor is in a powering state, so that sudden changes in the throttle coefficient of the first variable throttle valve are mitigated, and thrust fluctuations of the hydraulic cylinder caused by fluctuations in the throttle coefficient of the first variable throttle valve can be suppressed.

The throttle coefficient calculation unit in the cylinder device may gradually reduce the throttle coefficient of the first variable throttle valve based on the square of the time that has elapsed since the throttle coefficient of the first variable throttle valve began to be changed. With a cylinder device configured in this way, the gradual reduction process changes the throttle coefficient in proportion to the square of the time that has elapsed since the gradual reduction process started, so that the change in the target throttle coefficient follows a quadratic curve, and it is possible to mitigate a sudden change in the thrust of the hydraulic cylinder 1 caused by fluctuations in the throttle coefficient of the first variable throttle valve when the operating state of the motor transitions from a powering state to a braking state.

As described above, according to the cylinder device of the present invention, regenerated power can be improved and regeneration can be performed efficiently.

FIG. 1 is a conceptual diagram of a cylinder device according to one embodiment. FIG. 2 is a model diagram showing the relationship between the flow rate and differential pressure of the cylinder device in one embodiment. FIG. 3 is a graph showing the rotational speed of the motor as a function of the flow rate through the pump, and the torque of the motor as a function of the pressure difference (pressure loss) as the liquid passes through the pump. FIG. 4 is a diagram showing the rotational speed of the motor and the range of torque that can be outputted. FIG. 5 is a diagram showing the configuration of the controller. FIG. 6 is a diagram showing a locus of operating points that are the intersections of the rotation speed and torque of the motor, and an approximation curve for determining the zero cross torque. FIG. 7 is a diagram showing the relationship between the operating point of the motor and the control of the throttle coefficient of the first variable throttle valve by the controller. FIG. 8 is a map for determining the throttle coefficient of the first variable throttle valve from the zero cross torque. FIG. 9 is a diagram showing an example of a flowchart of the control of the throttle coefficient of the first single-sided throttle valve in the controller.

The present invention will be described below based on the embodiment shown in the figures. As shown in FIG. 1, the cylinder device A in one embodiment is configured with a hydraulic cylinder 1 and a controller 11.

Each part of the cylinder device A will be described in detail below. As shown in FIG. 1, the hydraulic cylinder 1 operates in parallel with a cylinder 2 and a piston 3 that is movably inserted into the cylinder 2 and partitions the inside of the cylinder 2 into two working chambers R1 and R2. A first flow path 4 and a second flow path 5 that communicate the chambers R1 and R2, a first variable throttle valve 6 provided in the middle of the first flow path 4, and a first variable throttle valve 6 provided in the middle of the second flow path 5 in series. The cylinder 2 includes a second variable throttle valve 7 and a bidirectional discharge pump 9 driven by a motor 8, and the cylinder 2 is filled with liquid and sealed. Further, the piston 3 is connected to a rod 10 that is movably inserted into the cylinder 2. In the case of this hydraulic cylinder 1, the rod 10 protrudes from both ends of the cylinder 2, which is a so-called double rod type cylinder device. It is said that

When the hydraulic cylinder 1 is applied to a vehicle, the cylinder 2 is connected to one of the sprung and unsprung members of the vehicle, and the rod 10 is connected to the other of the sprung and unsprung members, and is interposed between the sprung and unsprung members. When the hydraulic cylinder 1 is applied to a vehicle and used, the thrust it exerts suppresses vibrations of the vehicle body, which is the sprung member, and the vehicle wheels, which are the unsprung members.
In this specification, the hydraulic cylinder 1 is said to extend when the rod 10 moves together with the piston 3 relative to the cylinder 2 upward in Fig. 1, and conversely, the hydraulic cylinder 1 is said to contract when the rod 10 moves together with the piston 3 relative to the cylinder 2 downward in Fig. 1. Although the hydraulic cylinder 1 is configured as a double rod type in the illustrated example, it may be configured as a single rod type.

As described above, the cylinder 2 is divided by the piston 3 into an extension side working chamber R1 at the top in FIG. 1 and a compression side working chamber R2 at the bottom in FIG. 1, and each of the working chambers R1 and R2 is filled with a liquid such as hydraulic oil. The liquid may be other liquids such as water or an aqueous solution in addition to hydraulic oil. As described above, the hydraulic cylinder 1 is a double-rod type hydraulic cylinder, and even if the rod 10 moves up and down relative to the cylinder 2 together with the piston 3 in FIG. 1, the volume displaced by the rod 10 in the cylinder 2 does not change. Therefore, the hydraulic cylinder 1 does not have a reservoir to compensate for the volume of the rod 10 moving in and out of the cylinder 2, but may have an accumulator connected to the inside of the cylinder 2 to compensate for the volume change due to the temperature change of the liquid.

The pump 9 is set to be of a bidirectional discharge type, such as a vane pump, gear pump, or axial pump, which is equipped with a rotating shaft (not shown) and can suck in and discharge fluid by rotating the rotating shaft, and conversely, can suck in and discharge fluid by rotating the rotating shaft. Any material that can forcibly drive the rotating shaft by the flow may be used. Further, the rotating shaft of the pump 9 is connected to a motor 8, and the motor 8 can be driven by electricity, and when forced to rotate by an input from the pump 9 side, generates electricity to pump the pump 9. Any motor that generates a torque that suppresses the rotation of the motor may be used, and various types of motors, whether direct current or alternating current, such as brushless motors, induction motors, synchronous motors, etc., can be used.

The hydraulic cylinder 1 rotates a pump 9 with a motor 8 to move liquid from the expansion side working chamber R1 to the pressure side working chamber R2, or from the pressure side working chamber R2 to the expansion side working chamber R1 in a second flow. By feeding it through the passage 5, it is possible to expand and contract spontaneously and generate thrust in a desired direction. In addition, when the hydraulic cylinder 1 is forcibly expanded or contracted by an external input, the hydraulic cylinder 1 is moved from the expansion side working chamber R1 to the compression side working chamber R2, or from the compression side working chamber R2 to the expansion side working chamber R1. The pump 9 to which the torque of the motor 8 is transmitted to the flow of liquid moving to the chamber R1 via the second flow path 5 can generate thrust in a direction that provides resistance and prevents expansion and contraction.

Furthermore, when the hydraulic cylinder 1 is forcibly expanded or contracted, the motor 8 is forcibly driven via the pump 9 by the flow of liquid flowing back and forth in the second flow path 5, so that the motor 8 absorbs the kinetic energy of the liquid. is converted into electrical energy and can be regenerated. Note that the electric power regenerated by the motor 8 may be transmitted to an external device, or may be stored in a power storage device.

In other words, the first variable throttle valve 6 is provided in the first flow path 4 that bypasses the pump 9 and communicates between the working chambers R1 and R2, and the second variable throttle valve 7 is provided in the second flow path 5 together with the pump 9. Therefore, the first variable throttle valve 6 is arranged in parallel with the second variable throttle valve 7 and the pump 9. The first variable throttle valve 6 and the second variable throttle valve 7 are capable of changing the throttle coefficient, which is the ratio of the passing flow rate to the pressure loss, by changing the opening degree and the valve passage length. Specifically, for example, various valves such as a variable choke and a variable orifice can be used, and the throttle coefficient can be changed by driving the valve body (not shown) with a drive source such as a solenoid or a motor. The drive source that changes the throttle coefficient in the first variable throttle valve 6 and the second variable throttle valve 7 is controlled by the controller 11.

Regarding the arrangement relationship between the pump 9 and the second variable throttle valve 7, the pump 9 may be arranged on either side of the working chamber R1 or the working chamber R2. Further, the fluid filled in the cylinder 2 may be any fluid, such as oil, water, aqueous solution, or gas.

Now, the hydraulic cylinder 1 configured in this way can function as an actuator that expands and contracts by itself when power is supplied to the motor 8 from the controller 11 side to drive the pump 9. When the hydraulic cylinder 1 is expanded or contracted in response to the rotation, the rotation of the pump 9 is suppressed by the torque of the motor 8. In other words, the motor 8 is used in the braking region to apply a torque to the motor 8 that is opposite to the direction of rotation of the pump 9. The damping force can be generated in cooperation with the motor 8, the first variable throttle valve 6, and the second variable throttle valve 7. When the motor 8 is used in the braking region, the rotational speed and torque of the motor 8 can be controlled by adjusting the throttling coefficients of the first variable throttle valve 6 and the second variable throttle valve 7.

Note that when applying current to the motor 8 to drive the pump 9, that is, when using the motor 8 in the power running region and causing the hydraulic cylinder 1 to function as an actuator, the first variable throttle valve 6 is fully closed and the first While preventing the working chambers R1 and R2 from communicating with each other via the flow path 4, the second variable throttle valve 7 is fully opened, and the second variable throttle valve 7 applies unnecessary resistance to the flow of the liquid, causing energy loss. Make sure not to.

Here, we will use the model diagram shown in Figure 2 to explain how to control the load (rotational speed and torque) of the motor 8 when the hydraulic cylinder 1 is extended or retracted by an external force. Note that the pump 9 provides resistance to the flow of liquid by the torque transmitted from the motor 8, causing pressure loss when the liquid passes through, so it can be treated as equivalent to a variable throttle valve. Therefore, in Figure 2, the motor 8 and pump 9 are shown as one variable throttle valve M.

Let P be the differential pressure between one working chamber R1 and the other working chamber R2 when the hydraulic cylinder 1 expands and contracts, and the flow rate (hereinafter simply referred to as flow rate) of the fluid flowing out from one working chamber R1 per unit time. ) is Q, the throttle coefficient which is the ratio of the flow rate q1 of the fluid passing through the first variable throttle valve 6 divided by the differential pressure (pressure loss) P generated at the first variable throttle valve 6 is C1, and the second variable throttle valve The throttle coefficient, which is the ratio of the flow rate q2 of the fluid passing through the valve 7 divided by the differential pressure (pressure loss) p2 generated at the second variable throttle valve 7, is set to C2, and the fluid passes through the variable throttle valve M consisting of the motor 8 and the pump 9. Let Cm be the throttle coefficient, which is the ratio of the flow rate q2 of the fluid divided by the differential pressure (pressure loss) pm generated at the variable throttle valve M, then the following equation (1) is obtained.

Here, if we set C = C2 x Cm/(C2 + Cm), equation (1) can be written as equation (2) below.

Furthermore, the total flow rate Q = q1 + q2 holds true, and the differential pressure P generated at the first variable throttle valve 6 is equal to the differential pressure generated across the variable throttle valve M, which is composed of the second variable throttle valve 7, the motor 8, and the pump 9. Therefore, the following equation (3) holds true.

When formula (3) is substituted into formula (2) and summarized, the following formula (4) is obtained.

And, as can be seen from the above equation (4), if the flow rate Q and the differential pressure P are not changed, the flow rate q2 can be changed by changing the restriction coefficient C1.

That is, by adjusting the flow rate q1 in the first variable throttle valve 6 that bypasses the pump 9 by changing the throttle coefficient C1, the flow rate q2 passing through the variable throttle valve M can be changed. When changing the variable throttle valve 6 from a fully closed state to a fully open state, the rotational speed of the motor 8 can be increased or decreased by increasing or decreasing the flow rate q2.

Further, the flow rate in the second variable throttle valve 7 and the variable throttle valve M is q2, the overall pressure difference is P, the differential pressure (pressure loss) in the variable throttle valve M is pm, and the flow rate in the second variable throttle valve 7 and the variable throttle valve M is q2. The composite throttle coefficient C of the second variable throttle valve 7 and the variable throttle valve M is C=C2×Cm/(C2+Cm) as described above, so if we focus only on the second variable throttle valve 7 and the variable throttle valve M, we can obtain the following: We obtain equation (5).

As can be understood from the above equation (5), when the flow rate q2 and the differential pressure P are not changed, the differential pressure pm at the variable throttle valve M can be changed by changing the throttle coefficient C2.

In other words, by changing the throttling coefficient C2, the differential pressure pm that occurs when the fluid passes through the pump 9 can be changed. For example, when the second variable throttling valve 7 is shifted from a fully closed state to a fully open state, the differential pressure pm can be increased or decreased, thereby increasing or decreasing the torque that must be borne by the motor 8.

In a state where the flow rate Q and the differential pressure P are kept constant, the rotational speed of the motor 8 is made to correspond to the flow rate passing through the pump 9, and the torque of the motor 8 is made to correspond to the differential pressure when the fluid passes through the pump 9. To explain this with reference to the graph shown in FIG. 3, which corresponds to pressure loss, by changing the throttling coefficient C2 of the second variable throttle valve 7, the torque to be borne by the motor 8 (burden torque) can be changed on the vertical axis. By changing the throttle coefficient C1 of the first variable throttle valve 6, the rotational speed of the motor 8 can be adjusted along the horizontal axis. The burden torque of the motor 8 is the torque that acts between the motor 8 and the pump 9.

In detail, point a in FIG. 3 shows the relationship between the rotation speed and the load torque of the motor 8 when the second variable throttle valve 7 is fully open to maximize the throttle coefficient C2 and the first variable throttle valve 6 is fully closed to minimize the throttle coefficient C1; point b shows the relationship between the rotation speed and the load torque of the motor 8 when the second variable throttle valve 7 is fully open to maximize the throttle coefficient C2 and the first variable throttle valve 6 is fully open to maximize the throttle coefficient C1; point c shows the relationship between the rotation speed and the load torque of the motor 8 when the second variable throttle valve 7 is fully closed to minimize the throttle coefficient C2 and the first variable throttle valve 6 is fully closed to minimize the throttle coefficient C1; and point d shows the relationship between the rotation speed and the load torque of the motor 8 when the second variable throttle valve 7 is fully closed to minimize the throttle coefficient C2 and the first variable throttle valve 6 is fully open to maximize the throttle coefficient C1. That is, by changing the throttle coefficients C1 and C2 of the first variable throttle valve 6 and the second variable throttle valve 7, the rotation speed and load torque of the motor 8 can be adjusted within the range surrounded by points a, b, c, and d.

Specifically, when the intersection of the rotation speed and the load torque of the motor 8 (the operating point of the motor) is at point a, increasing the throttling coefficient C1 of the first variable throttle valve 6 can shift it toward point b, decreasing the throttling coefficient C2 of the second variable throttle valve 7 can shift it toward point c, and increasing the throttling coefficient C1 of the first variable throttle valve 6 and decreasing the throttling coefficient C2 of the second variable throttle valve 7 can shift it toward point d. In other words, by controlling the throttling coefficients of the first variable throttle valve 6 and the second variable throttle valve 7, it is possible to control the rotation speed and the load torque of the motor 8.

In the explanation of Figure 3, we assume that the flow rate Q and the differential pressure P are constant, so there is no state in which the motor 8 is rotating despite its burden torque being 0, or in which there is a burden torque even though the rotation speed is 0. Therefore, the line connecting points b and d and the line connecting points d and c indicate the boundaries of the range in which the operating point of motor 8 can be, and the operating point of motor 8 will never be a value on these lines.

By the way, the load torque range that can be output for any given rotational speed of the motor 8 is determined by a rotational speed torque coordinate system in which the load torque is plotted on the vertical axis and the rotational speed is plotted on the horizontal axis, as shown in FIG. In the graph, each quadrant is a hatched area surrounded by a straight line parallel to the horizontal axis and a curved line connected to the straight line. Note that the straight line indicates the upper limit of the torque burden on the motor 8, and is a boundary that occurs due to the current being limited by a current limiter (not shown) provided in the controller 11. The curve is also a line that separates a burden torque region that can be generated and a burden torque region that cannot be generated at the rotational speed at that time, and is a boundary line determined by characteristics such as the power supply voltage and the induced power of the motor 8 (not shown). be. The sign of the torque in the forward rotation direction of the motor 8 is positive, and the sign of the torque in the reverse direction is negative, and the sign of the rotational speed when the motor 8 rotates in the forward rotation direction is positive, and the sign of the torque in the reverse direction is The sign is negative.

As can be understood from FIG. 4, the higher the rotational speed of the motor 8 in each quadrant, the smaller the upper limit of the load torque that can be outputted. That is, when the first variable throttle valve 6 is closed to block the first flow path 4 and the entire flow rate of the liquid flowing between the working chambers R1 and R2 is made to flow to the pump 9, the expansion and contraction speed of the hydraulic cylinder 1 becomes high. The more the rotation speed of the motor 8 increases, the more the output burden torque of the motor 8 becomes smaller. Note that the broken line shown in FIG. 4 is the maximum regeneration efficiency straight line that indicates the relationship between the rotational speed at which the regeneration efficiency is maximum and the burden torque, and when the operating point of the motor 8 is on the maximum regeneration efficiency straight line, Regeneration efficiency is maximized.

In addition, in the second quadrant, where the rotation speed is negative and the burden torque is positive, and in the fourth quadrant, where the rotation speed is positive and the burden torque is negative, the motor 8 is operating in the braking region where power regeneration is possible, and in the first quadrant, where the rotation speed is positive and the burden torque is positive, and in the third quadrant, where the rotation speed is negative and the burden torque is negative, the motor 8 is operating in the powering region where power is consumed. Thus, the motor 8 is in a braking state when operating in the braking region, and in a powering state when operating in the powering region.

When the motor 8 is operating in the braking region, comparing points g and h, which are located on the horizontal axis side of the maximum regeneration efficiency straight line in FIG. In this case, the regenerative power of the motor 8 becomes larger. The maximum regeneration efficiency straight line is a straight line that shows the relationship between the rotation speed of the motor 8 and the torque that maximizes the regeneration efficiency.If the operating point of the motor 8 is on the maximum regeneration efficiency straight line, the regeneration efficiency is is the maximum. If the rotation speed is kept constant in this way, the regeneration efficiency will be maximized by locating the operating point of the motor 8 on the straight line of maximum regeneration efficiency, but if the rotation speed of the motor 8 is made higher, then the regeneration efficiency will be maximized. There is room to increase regenerative power. Therefore, when the motor 8 is operating in the braking range, by increasing the rotational speed as high as possible within the output range, the regenerated power can be increased compared to the conventional cylinder device.

As shown in FIG. 5, the controller 11 includes a thrust control unit 20 that controls the motor 8 in response to a thrust command indicating a target thrust of the hydraulic cylinder 1 from a higher-level control device, a first variable throttle valve 6, and A throttle valve control section 21 that controls the second variable throttle valve 7 is provided. The throttle valve control section 21 includes a first control section 22 that controls the throttle coefficient of the first variable throttle valve 6 and a second control section 23 .

The thrust control unit 20 includes a current command generating unit 20a that, upon receiving a thrust command indicating the target thrust of the hydraulic cylinder 1 from a higher-level control device, determines a target current to be supplied to the motor 8 and outputs a current command indicating the target current, and a motor control unit 20b that, upon receiving the current command generated by the current command generating unit 20a, feeds back the current flowing through the motor 8 to control the current flowing through the motor 8 according to the target current. In this embodiment, the hydraulic cylinder 1 is applied to a vehicle, and the higher-level control device determines the thrust to be generated in the hydraulic cylinder 1 mainly for the purpose of suppressing the vibration of the vehicle body as a sprung member. The thrust command may be determined so as to enable not only the reduction of the vibration of the vehicle body but also the reduction of the vibration of the wheels as unsprung members. The thrust control unit 20 may also determine a thrust command by itself, rather than obtaining a thrust command from a higher-level control device, by detecting vibration information of the vehicle body, or the vehicle body and wheels in the vehicle, or by receiving such vibration information from the vehicle.

The current command generating unit 20a performs a calculation process to obtain a target current corresponding to the torque to be output to the motor 8 by feeding back the actual thrust generated by the hydraulic cylinder 1, and performing proportional, integral and differential compensation for the control deviation between the target thrust indicated by the thrust command and the actual thrust. The thrust of the hydraulic cylinder 1 is input to the current command generating unit 20a from an actual thrust detecting unit 25 including a pressure sensor 25a for detecting the pressure of the working chamber R1, a pressure sensor 25b for detecting the pressure of the working chamber R2, and a calculation unit 25c for multiplying the difference between the pressure of the working chamber R1 and the pressure of the working chamber R2 by the pressure receiving area of the piston 3 to obtain the thrust generated by the hydraulic cylinder 1. The current command generating unit 20a may be configured in any way as long as it can obtain a target current from the thrust command and generate a current command. In addition, since the thrust generated by the hydraulic cylinder 1 can be grasped by detecting the load provided on the rod 10, the actual thrust detecting unit 25 may be a sensor for detecting the load acting on the rod 10. In addition, the thrust control unit 20 may include an observer that detects the state quantities of the hydraulic cylinder 1, such as the throttle coefficients of the first variable throttle valve 6 and the second variable throttle valve 7, the rotation speed of the motor 8, and the torque, instead of detecting the pressure and load described above, and estimates the thrust of the hydraulic cylinder 1 from the state quantities. In this case, the current command generation unit 20a may feed back the thrust estimated by the observer to obtain the target current. The motor control unit 20b may include a drive circuit suitable for controlling the current of the motor 8 depending on the type of the motor 8, and may control the current of the motor 8 according to the current command.

The throttle valve control unit 21 monitors the rotational speed and torque of the motor 8 and controls the throttle coefficient of the first variable throttle valve 6 and the first control unit 22 that controls the throttle coefficient of the second variable throttle valve 7. A second control section 23 is provided. If the motor 8 is equipped with a sensor (not shown) such as a resolver capable of detecting the rotational position of the rotor, the rotational speed of the motor 8 may be obtained from the rotational position information of the rotor detected by the sensor. Regarding the torque of the motor 8, if the motor 8 is a DC motor or a motor equivalent to a DC motor, it is proportional to the current flowing through the motor 8, so the current can be regarded as torque as it is, and the current of the motor 8 can be detected. Since the motor control section 20b is equipped with a sensor for detecting the current value, the current value may be obtained from the motor control section 20b and used as the torque of the motor 8. Note that the throttle valve control unit 21 may separately include a sensor that detects the rotational speed of the motor 8, a sensor that detects the torque of the motor 8, or a sensor that detects the current of the motor 8. The throttle valve control section 21 sequentially takes in the rotational speed and torque of the motor 8 at a predetermined calculation cycle, and processes the taken-in rotational speed and torque using the first control section 22 and the second control section 23 . The throttle valve control unit 21 processes the torque of the motor 8, but as described above, the current flowing through the motor 8 can be regarded as torque, so if the current flowing through the motor 8 is treated as torque and processed, good.

The second control unit 23 includes a drive circuit for energizing the drive source of the second variable throttle valve 7, and basically maximizes the throttle coefficient of the second variable throttle valve 7 to control the flow area of the second variable throttle valve 7 to the maximum. The second variable throttle valve 7 prevents the passage of the liquid discharged by the pump 9 and becomes a resistance when the hydraulic cylinder 1 operates as an actuator, so the second control unit 23 maximizes the throttle coefficient of the second variable throttle valve 7 while the motor 8 is operating. Since the second variable throttle valve 7 provides resistance to the flow of liquid passing through the second flow path 5, the torque borne by the motor 8 can be increased or decreased by increasing or decreasing the throttle coefficient. Therefore, the second control unit 23 monitors the rotation speed and torque of the motor 8, and increases the throttle coefficient of the second variable throttle valve 7 to reduce the torque borne by the motor 8 so that the operating point of the motor 8 does not fall into a load torque region that cannot be generated.

When the motor 8 is operating in a braking state, the first control unit 22 performs regenerative control to reduce the throttling coefficient of the first variable throttle valve 6 so as to increase the rotation speed of the motor 8, and when the motor 8 is operating in a powered state, the first control unit 22 controls the throttling coefficient of the first variable throttle valve 6 to a preset initial value. The initial value is set to a value suitable for thrust control of the hydraulic cylinder 1 when the motor 8 is operating in a powered state.

Therefore, the first control unit 22 uses a first filter 30a that removes a component higher than the unsprung resonance frequency from the rotational speed of the motor 8 and outputs the filtered rotational speed, and a first filter 30a that removes the component higher than the unsprung resonance frequency from the torque of the motor 8. A filter processing unit 30 including a second filter 30b that removes components and outputs a filtered torque, and determines whether the motor 8 is in a braking state based on the filtered rotational speed and the filtered torque. A braking state determination unit 31 determines whether the rotational speed is 0 when the motor 8 transitions from the power running state to the braking state. The torque estimator 33 estimates the zero cross torque when A throttle coefficient calculation section 34 that controls the first variable throttle valve 6 and a current supplied to a drive source (not shown) in the first variable throttle valve 6 in response to a command instructing the throttle coefficient determined by the throttle coefficient calculation section 34. The drive circuit 35 is configured to include a drive circuit 35 that performs the following steps.

The filter processing unit 30 includes a first filter 30a that removes components of the rotation speed of the motor 8 that are equal to or higher than the unsprung resonance frequency band and outputs a filtered rotation speed, and a second filter 30b that removes components of the torque of the motor 8 that are equal to or higher than the unsprung resonance frequency band and outputs a filtered torque. The filter processing unit 30 processes the rotation speed and torque of the motor 8 that are input sequentially, and outputs signals of the filtered rotation speed and the filtered torque.

When the hydraulic cylinder 1 is used by being interposed between the vehicle body, which is the sprung member of the vehicle, and the wheels, which are the unsprung members, the hydraulic cylinder 1 expands and contracts due to the relative movement between the vehicle body and the wheels, and vibrations of the vehicle body and wheels are input to the hydraulic cylinder 1. The vibrations input to the hydraulic cylinder 1 also change the flow rate of liquid passing through the pump 9 in the second flow path 5, and the rotation speed and torque of the motor 8 also fluctuate. Therefore, high-frequency components in the resonant frequency band of the wheels and high-frequency noise are superimposed on the rotation speed and torque of the motor 8 before processing by the filter processing unit 30.

Therefore, if processing by the filter processing unit 30 is not performed, the operating point of the motor 8 will shift in an oscillatory manner at high frequencies, and hunting may occur in subsequent processing such as determining the operating state of the motor 8. For this reason, in this embodiment, the first filter 30a and the second filter 30b are bandpass filters that can extract the resonant frequency components of the sprung member. Since the resonant frequency band of the sprung member is approximately 1 Hz to 2 Hz, the first filter 30a and the second filter 30b are set to have characteristics that can extract components of 1 Hz to 2 Hz.

In this way, in the cylinder device A of the present embodiment, the rotational speed and torque of the motor 8 are processed by the filter processing section 30, and components higher than the high frequency unsprung resonance frequency are removed from the rotational speed and torque of the motor 8. Therefore, it becomes possible to accurately grasp the braking state of the motor 8 according to the vibration of the sprung member in the vehicle, and it becomes possible to appropriately control the throttling coefficient of the first variable throttle valve 6 by the first control section 22. . Note that the first filter 30a and the second filter 30b in the filter processing unit 30 are filters that extract components in the sprung resonance frequency band, but are low-pass filters that can remove at least components above the sprung resonance frequency band. It may be. In this way, even if the first filter 30a and the second filter 30b are low-pass filters that can remove components above the unsprung resonance frequency band, the vibrations and noise of the unsprung members can be removed from the rotational speed and torque signals. , the braking state of the motor 8 can be grasped with high accuracy, and the throttle coefficient of the first variable throttle valve 6 can be appropriately controlled by the first control section 22. Note that by providing the first filter 30a and the second filter 30b in the filter processing section 30, it is possible to accurately grasp the braking state of the motor 8, but the first filter 30a and the second filter 30b may be omitted. It is possible.

Subsequently, the braking state determination unit 31 determines whether the motor 8 is in the braking state based on the filtered rotational speed and the filtered torque. Specifically, the braking state determination unit 31 determines in which quadrant in FIG. 4 the operating point of the motor 8 is located from the sign of the rotational speed after filtering and the sign of the torque after filtering, and 8 is in a braking state or a powering state. After determining the operating state of the motor 8, the braking state determining section 31 inputs the determination result to the torque estimating section 33 and the aperture coefficient calculating section 34.

Specifically, the braking state determination unit 31 determines that when the rotational speed after filtering is positive and the torque after filtering is positive, that is, if the rotational speed after filtering is Mv and the torque after filtering is Tm. , Mv≧0 and Tm≧0, it is determined that the operating point of the motor 8 is in the powering region of the first quadrant in FIG. 4, and the operating state of the motor 8 is determined to be the powering state in the first quadrant. do.

In addition, when the filtered rotation speed is negative and the filtered torque is positive, that is, when Mv<0 and Tm≧0, the braking state determination unit 31 determines that the operating point of the motor 8 is in the braking region of the second quadrant in FIG. 4, and determines that the operating state of the motor 8 is in a braking state in the second quadrant.

Furthermore, if the filtered rotational speed is negative and the filtered torque is negative, and Mv<0 and Tm<0, the braking state determination unit 31 determines that the operating point of the motor 8 is in the powering region of the third quadrant in FIG. 4, and determines that the operating state of the motor 8 is a powering state in the third quadrant.

Then, when the filtered rotation speed is positive and the filtered torque is negative, that is, when Mv≧0 and Tm<0, the braking state determination unit 31 determines that the operating point of the motor 8 is in the braking region of the fourth quadrant in FIG. 4, and determines that the operating state of the motor 8 is in a braking state in the fourth quadrant.

In this way, the braking state determination unit 31 determines whether the value of Mv is positive or negative, and whether the value of Tm is positive or negative, so that the operating point of the motor 8 falls within the four quadrants. It is determined whether the operating state of the motor 8 is a braking state or a powering state.

The rotational acceleration calculation unit 32 calculates the rotational acceleration of the motor 8 based on the filtered rotational speed input from the first filter 30a. The rotational acceleration calculation unit 32 differentiates or high-pass filters the filtered rotational speed to obtain the filtered acceleration. Instead of differentiating the filtered rotational speed, the rotational acceleration calculation unit 32 may calculate the difference between the filtered rotational speed obtained one time before and the filtered rotational speed obtained this time for each calculation process cycle, and use this difference as the rotational acceleration. The rotational acceleration calculation unit 32 then inputs the obtained rotational acceleration to the torque estimation unit 33 and the throttling coefficient calculation unit 34.

As shown in FIG. 5, the torque estimation unit 33 calculates the filtered rotational speed, the filtered torque, the determination result of the braking state determination unit 31, and the rotational acceleration of the motor 8 determined by the rotational acceleration calculation unit 32. Based on this, the zero cross torque when the rotational speed becomes 0 when the motor 8 moves from the power running state to the braking state is estimated.

Specifically, when the braking state determination unit 31 determines that the operating state of the motor 8 is in the first quadrant powering state or the third quadrant powering state, the torque estimation unit 33 estimates the zero cross torque if the rotational acceleration of the motor 8 satisfies the following condition. When the motor 8 is in the first quadrant powering state, the torque estimation unit 33 determines the zero cross torque using an equation for estimating the zero cross torque with the filtered rotation speed and filtered torque obtained earliest from the time point when the condition is met as parameters, under the condition that the rotational acceleration of the motor 8 becomes negative and the absolute value of the rotational acceleration of the motor 8 becomes equal to or greater than the threshold value α.

Further, the torque estimating unit 33 sets the condition that when the motor 8 is in the third quadrant power running state, the rotational acceleration of the motor 8 becomes positive and the absolute value of the rotational acceleration of the motor 8 becomes equal to or greater than the threshold value α. When this is achieved, the zero-crossing torque is determined using a formula for estimating the zero-crossing torque using the filtered rotational speed and the filtered torque as parameters.

If the rotational acceleration of the motor 8 is dω/dt, the filtered rotational speed is ωm1, the filtered torque is Tm1, and the zero-cross torque is Tm2, the torque estimation unit 33 substitutes the filtered rotational speed ωm1 and the filtered torque Tm1 into the formula Tm2 = Tm1 - Kt ωm1 to obtain the zero-cross torque Tm2 when the motor 8 is in the first quadrant powering state and dω/dt < 0 and |dω/dt | ≧ α are satisfied. Kt in the formula is an arbitrary coefficient. Also, when the motor 8 is in the third quadrant powering state and dω/dt ≧ 0 and |dω/dt | ≧ α are satisfied, the torque estimation unit 33 substitutes the filtered rotational speed ωm1 and the filtered torque Tm1 into the formula Tm2 = Tm1 - Kt ωm1 to obtain the zero-cross torque Tm2.

In other words, the torque estimation unit 33 is configured to obtain the zero cross torque under the condition that the motor 8 is in a powered state, the rotational acceleration acts in a direction to decelerate the rotational speed of the motor 8, and the rotational acceleration that decelerates the rotational speed of the motor 8 becomes large to a certain extent. The torque estimation unit 33 uses a linear approximation to obtain a point where the operating point of the motor 8 will have a rotational speed of 0 in the future, starting from the operating point of the motor 8 at a time before the operating state of the motor 8 transitions from the powered state to the braking state when the rotational speed crosses 0 when the motor 8 is decelerating in the powered state. Consider a straight line shown by a dashed line in FIG. 6 that passes through the actual operating point of the motor 8 at a certain time t1 before the zero crossing, with respect to the trajectory of the operating point when the motor 8 transitions from the powered state to the braking state, shown by a solid line in FIG. 6. The throttling coefficient calculation unit 34, which will be described later, starts control to reduce the throttling coefficient of the first variable throttle valve 6, starting from the time t1 when the above-mentioned condition is met. Since the throttling coefficient of the first variable throttle valve becomes smaller from time t1 before the rotational speed becomes zero when the operating point of the motor 8 transitions from the powering region to the braking region, the trajectory of the operating point of the motor 8 progresses linearly from when the above condition is met until the rotational speed becomes zero, and the torque decreases in proportion to the rotational speed. Therefore, if the slope of the above-mentioned straight line is appropriately selected, the torque at point X where the straight line crosses zero will be a value that is close to the torque at the actual zero cross. Therefore, the zero cross torque can be accurately estimated from the filtered rotational speed and filtered torque, which are information on the actual operating point that passes before the zero crossing operating point.

It is preferable that the rotational speed after filtering and the torque after filtering used to estimate the zero cross torque are set immediately before the operating state of the motor 8 changes from the powering state to the braking state. If the decelerating torque increases to a certain extent, the rotational speed may be greatly decelerated and the operating state of the motor 8 may change from the powering state to the braking state. Provided that the rotational speed is decelerated and the absolute value of the rotational acceleration is greater than the threshold α, the rotational speed after filtering and the torque after filtering at the operating point of the motor 8 at the time when the conditions are met are calculated. The zero cross torque is calculated from the value of . By determining the zero-cross torque in this way, the torque estimator 33 can accurately estimate the zero-cross torque at a time point before the operating point of the motor 8 actually crosses the zero rotation speed line.

In estimating the zero-cross torque, the torque estimation unit 33 may obtain the gradient of the operating point of the motor 8 at the time when the above conditions are met, and substitute K indicating the gradient of the approximate straight line to obtain the zero-cross torque, or may determine the torque of the motor 8 at the time when the rotation speed of the motor 8 is decelerated and the absolute value of the rotation speed of the motor 8 becomes equal to or less than a threshold value set to a value close to 0 as the zero-cross torque. However, as described above, if the operating state of the motor 8 is in the first quadrant powering state or the third quadrant powering state, the rotation acceleration is decelerating the rotation speed, and the absolute value of the rotation acceleration is greater than the threshold value α, and the zero-cross torque is obtained from the values of the filtered rotation speed and the filtered torque at the operating point of the motor 8 at the time when the conditions are met, the advantage of being able to accurately estimate the zero-cross torque using a simple calculation formula can be enjoyed.

Subsequently, the throttling coefficient calculation unit 34 sets a target throttling coefficient so that the throttling coefficient of the first variable throttle valve 6 is decreased from the time when the above-mentioned torque estimating unit 33 satisfies the trigger condition for estimating the zero cross torque. At the same time, on the condition that the operating state of the motor 8 changes from the braking state to the power running state, the motor 8 is set to be in the braking state and the target aperture coefficient that has been reduced is returned to the original initial value. The target aperture coefficient calculated by the aperture coefficient calculating section 34 is input to the drive circuit 35. The drive circuit 35 applies current to a drive source (not shown) of the first variable throttle valve 6 so that the throttle coefficient of the first variable throttle valve 6 matches the target throttle coefficient. adjust.

In detail, when the braking state determination unit 31 determines that the operating state of the motor 8 is a powering state, the throttle coefficient calculation unit 34 performs a gradual increase process to make the throttle coefficient of the first variable throttle valve 6 a predetermined initial value. As will be described in detail later, when the motor 8 is in a braking state, the throttle coefficient calculation unit 34 performs a process to reduce the target throttle coefficient, and the drive circuit 35 reduces the throttle coefficient of the first variable throttle valve 6, so that the throttle coefficient of the first variable throttle valve 6 is smaller when the motor 8 is in a braking state than when the motor 8 is in a powering state. Therefore, when the motor 8 transitions from a braking state to a powering state, the throttle coefficient calculation unit 34 performs a gradual increase process to return the reduced throttle coefficient of the first variable throttle valve 6 to the initial value set to a value larger than the throttle coefficient when the motor 8 is in a braking state.

The gradual increase process in the throttle coefficient calculation unit 34 will be described in detail. The throttle coefficient calculation unit 34 performs the gradual increase process when the operating state of the motor 8 is switched from the braking state to the powering state. Before the gradual increase process, that is, when the motor 8 is in the braking state, the throttle coefficient calculation unit 34 sets the braking throttle coefficient, which is set to a value smaller than the initial value, as the target throttle coefficient, so that the throttle coefficient of the first variable throttle valve 6 becomes the braking throttle coefficient. Therefore, when the condition for performing the gradual increase process is performed, the throttle coefficient calculation unit 34 calculates the formula Cref=Clow+Kcg· ^dt2 , where Cref is the pre-filtering throttle coefficient, Clow is the braking throttle coefficient, dt is the time elapsed after the start of the gradual increase process, and Kcg is the gradual increase rate. Next, the throttle coefficient calculation unit 34 performs low-pass filtering on the obtained pre-filtering throttle coefficient Cref to obtain the target throttle coefficient Cref ^* .

When the gradual increase process is started, the restriction coefficient calculation unit 34 repeats the above formula and low-pass filter process to sequentially update the value of the target restriction coefficient Cref ^* , gradually increasing the value of the target restriction coefficient Cref ^* over time. When the value of the target restriction coefficient Cref ^* becomes equal to or greater than the initial value, the restriction coefficient calculation unit 34 clamps the value of the target restriction coefficient Cref ^* to the initial value, and controls the restriction coefficient of the first variable throttle valve 6 to be the initial value. If the operating state of the motor 8 continues to be the power running state, the restriction coefficient calculation unit 34 maintains the target restriction coefficient at the initial value until a condition that triggers the torque estimation unit 33 to estimate the zero cross torque is satisfied. That is, as shown in Fig. 7, when the operating point of the motor 8 transitions from the braking region to the powering region, the restriction coefficient calculation unit 34 performs a gradual increase process to gradually increase the target restriction coefficient so that the restriction coefficient of the first variable throttle valve 6 is gradually increased from the braking restriction coefficient to the initial value, and if the motor 8 is in the powering state, the target restriction coefficient is maintained at the initial value until the following gradual decrease process is started, and the restriction coefficient of the first variable throttle valve 6 is maintained at the initial value. The solid line in Fig. 7 indicates the trajectory of the operating point of the motor 8, and the arrow indicates the direction in which the operating point of the motor 8 transitions. Note that, in the gradual increase process, when calculating the target restriction coefficient Cref ^* , the restriction coefficient calculation unit 34 may use the formula Cref ^* = Cpref ^* + Kcg ^Δt2 , where Cpref ^* is the previous target restriction coefficient, which is the target restriction coefficient obtained in the previous calculation, and Δt is the calculation period. In this case, since the previous target throttle coefficient Cref ^* when the gradual increase process is started is the braking throttle coefficient Clow, it is possible to obtain the same value of the target throttle coefficient Cref ^* as that obtained when the time dt that has elapsed since the start of the gradual increase process described above is used. In addition, by doing so, it is possible to avoid a sudden change in the value of the target throttle coefficient Cref ^* when the target throttle coefficient is not the braking throttle coefficient when the gradual increase process is executed.

As shown in FIG. 7, when the operating point of the motor 8 is about to transition from the powering region to the braking region, the throttle coefficient calculation unit 34 starts a gradual reduction process to gradually reduce the throttle coefficient of the first variable throttle valve 6. When the motor 8 is in the first quadrant powering state, the throttle coefficient calculation unit 34 performs a gradual reduction process to gradually reduce the target throttle coefficient and reduce the throttle coefficient of the first variable throttle valve 6 to the braking throttle coefficient calculated from the zero cross torque calculated by the torque estimation unit 33, under the condition that the rotational acceleration of the motor 8 becomes negative and the absolute value of the rotational acceleration of the motor 8 becomes equal to or greater than the threshold value α, if the condition is met. Also, when the motor 8 is in the third quadrant powering state, the throttle coefficient calculation unit 34 performs a gradual reduction process to gradually reduce the target throttle coefficient and reduce the throttle coefficient of the first variable throttle valve 6 to the braking throttle coefficient calculated from the zero cross torque calculated by the torque estimation unit 33, under the condition that the rotational acceleration of the motor 8 becomes positive and the absolute value of the rotational acceleration of the motor 8 becomes equal to or greater than the threshold value α, if the condition is met.

The throttle coefficient calculation unit 34 may start the gradual reduction process when it receives a zero-cross torque input from the torque estimation unit 33, since the condition for starting the gradual reduction process is the same as the condition for the torque estimation unit 33 to find the zero-cross torque. However, it may also be possible to determine whether the above condition is met separately from the torque estimation unit 33.

When the aperture coefficient calculation unit 34 receives zero cross torque input from the torque estimation unit 33, as shown in FIG. Find the time aperture coefficient. The value of the aperture coefficient during braking is set to a value smaller than the initial value. The braking throttling coefficient is set to a smaller value as the zero cross torque becomes larger, so that the flow rate passing through the second flow path 5 in which the pump 9 is installed increases. The characteristics of the zero cross torque and the throttle coefficient during braking in the map are calculated backward from the zero cross torque of the motor 8, and the throttle coefficient during braking does not change the actual thrust of the hydraulic cylinder 1 when the rotational speed of the motor 8 becomes 0. It is set to a value like this. Zero cross torque is the torque output when the motor 8, which is controlled according to the thrust command generated by the hydraulic cylinder 1, transitions from the power running state to the braking state, so the throttle coefficient during braking is If the throttle coefficient of the first variable throttle valve 6 when the motor 8 is in the braking state is controlled to be the throttle coefficient during braking, the actual thrust of the hydraulic cylinder 1 will not change even if the regenerative power is controlled to be large. fluctuations can be suppressed.

After determining the braking aperture coefficient from the zero cross torque, the aperture coefficient calculation unit 34 gradually reduces the target aperture coefficient to the braking aperture coefficient. Specifically, until the motor 8 is in the power running state and the conditions for performing the gradual reduction process are fulfilled, the aperture coefficient calculation unit 34 sets the target aperture coefficient to an initial value larger than the braking aperture coefficient. Therefore, the throttling coefficient of the first variable throttle valve 6 is the braking throttling coefficient. Therefore, when the conditions for performing the gradual reduction process are fulfilled, the aperture coefficient calculation unit 34 sets the aperture coefficient before filter processing to Cref, the initial value to Cini, dt to the time elapsed after the start of the gradual increase process, and the gradual increase rate to Kcd. Then, the formula Cref=Cini-Kcd·dt ² is calculated. Subsequently, the aperture coefficient calculation unit 34 performs low-pass filter processing on the obtained pre-filter aperture coefficient Cref to obtain a target aperture coefficient Cref ^* .

When the gradual decrease process is started, the restriction coefficient calculation unit 34 repeats the above formula and low-pass filter process to sequentially update the value of the target restriction coefficient Cref ^* , gradually decreasing the value of the target restriction coefficient Cref ^* over time. When the value of the target restriction coefficient Cref ^* becomes equal to or less than the braking restriction coefficient, the restriction coefficient calculation unit 34 clamps the value of the target restriction coefficient Cref ^* to the value of the braking restriction coefficient, and controls the restriction coefficient of the first variable throttle valve 6 to match the braking restriction coefficient. If the operating state of the motor 8 continues to be in the braking state, the restriction coefficient calculation unit 34 maintains the target restriction coefficient at the braking restriction coefficient until the operating state of the motor 8 transitions from the braking state to the powering state. 7, when the operating state of the motor 8 is in a powering state and the condition for starting the gradual reduction process is satisfied, the restriction coefficient calculation unit 34 performs a gradual reduction process to gradually reduce the target restriction coefficient so as to gradually reduce the restriction coefficient of the first variable throttle valve 6 from the initial value to the braking restriction coefficient, and when the operating state of the motor 8 transitions from the powering state to the braking state and the motor 8 remains in the braking state, the restriction coefficient calculation unit 34 maintains the target restriction coefficient at the braking restriction coefficient until the motor 8 enters the powering state. It is preferable for the restriction coefficient calculation unit 34 to reduce the target restriction coefficient to the braking restriction coefficient by the gradual reduction process before the rotation speed at the operating point of the motor 8 becomes 0, because this makes it possible to increase the regenerative power from the time the operating state of the motor 8 enters the braking state, but the gradual reduction process may end after the operating point of the motor 8 enters the braking region. In the gradual reduction process, the throttle coefficient calculation unit 34 may use the formula Cref*=Cpref*-Kcd· ^Δt2 when calculating the target throttle coefficient Cref ^* , where Cpref ^* is the previous target throttle coefficient obtained in the previous calculation, ^and Δt is the calculation cycle. In this case, the previous target throttle coefficient Cref ^* when the gradual reduction process is started is the initial value Cini, so ^{that the value of the target throttle coefficient Cref* can} be obtained as in the case where the time dt that has elapsed since the start of the gradual reduction process described above is used. In this way, if the target throttle coefficient is not the initial value when the gradual reduction process is executed, a sudden change in the value of the target throttle coefficient Cref ^* can be avoided.

Therefore, when the motor 8 is in a braking state, the controller 11 controls the throttling coefficient of the first variable throttle valve 6 to a braking throttling coefficient smaller than the initial value, and the flow rate of the liquid passing through the pump 9 is increased to increase the rotation speed of the motor 8, thereby improving power regeneration. And when the motor 8 is in a braking state in this way, the cylinder device A controls to improve power regeneration by increasing the rotation speed of the motor 8, so that the power regenerated by the motor 8 increases compared to conventional cylinder devices, enabling efficient regeneration.

In addition, when the motor 8 is about to transition to the braking state, the aperture coefficient calculation unit 34 performs a gradual reduction process from the time the motor 8 is in the power running state. Since the throttling coefficient of the first variable throttle valve 6 is changed, regenerative power can be improved more efficiently.

Furthermore, the throttle coefficient calculation unit 34 performs a gradual reduction process to gradually reduce the throttle coefficient of the first variable throttle valve to the braking throttle coefficient that improves the regenerative power of the motor 8, thereby mitigating sudden changes in the throttle coefficient of the first variable throttle valve 6 when power regeneration is performed. Therefore, according to the cylinder device A, when the operating state of the motor 8 transitions from a powering state to a braking state and regenerative control is executed, it is possible to suppress thrust fluctuations of the hydraulic cylinder 1 caused by fluctuations in the throttle coefficient of the first variable throttle valve 6.

Furthermore, when the motor 8 transitions from the braking state to the powering state, the throttling coefficient calculation unit 34 performs a gradual increase process to gradually increase the throttling coefficient of the first variable throttle valve 6 to the hydraulic cylinder 1 when the motor 8 is in the powering state. Since the throttle coefficient is increased to an initial value suitable for controlling the thrust of the first variable throttle valve 6, sudden changes in the throttle coefficient of the first variable throttle valve 6 are alleviated. Therefore, according to the cylinder device A, when the operating state of the motor 8 changes from the braking state to the powering state, it is possible to suppress fluctuations in the thrust force of the hydraulic cylinder 1 caused by fluctuations in the throttling coefficient of the first variable throttle valve 6.

Further, in the gradual increase process and the gradual decrease process, the aperture coefficient calculation unit 34 changes the target aperture coefficient in proportion to the square of the time elapsed from the start of the gradual decrease process, so that the change in the target aperture coefficient draws a quadratic curve. Therefore, according to the cylinder device A, when the operating state of the motor 8 transitions from the braking state to the powering state and from the powering state to the braking state, the fluid generated by the variation in the throttling coefficient of the first variable throttle valve 6 is reduced. Sudden changes in the thrust of the pressure cylinder 1 can be alleviated. In addition, in the gradual increase process, the aperture coefficient calculation unit 34 may calculate Cref=Clow+Kcg·dt to obtain the pre-filtering aperture coefficient and change the target aperture coefficient in proportion to time, or in the gradual decrease process, The target aperture coefficient may be changed in proportion to time by calculating the aperture coefficient before filtering by calculating Cref=Cini-Kcd·dt.

In addition, the throttle coefficient calculation unit 34 of this embodiment performs low-pass filtering on the unfiltered throttle coefficient to obtain the target throttle coefficient, which can mitigate sudden changes in the target throttle coefficient and further mitigate sudden changes in the thrust of the hydraulic cylinder 1 caused by fluctuations in the throttle coefficient of the first variable throttle valve 6.

The controller 11 configured as described above controls the throttle coefficient of the first variable throttle valve 6 according to the flowchart shown in FIG. First, the controller 11 detects the rotational speed of the motor 8 and the torque flowing through the motor 8 (step F1). Subsequently, the controller 11 filters the rotational speed and torque of the motor 8 to obtain a filtered rotational speed and a filtered torque (step F2).

Further, the controller 11 determines whether the operating state of the motor 8 is a braking state based on the filtered rotational speed and the filtered torque (step F3). Subsequently, when the operating state of the motor 8 is the braking state, the controller 11 determines whether the target aperture coefficient Cref ^* is greater than or equal to the braking aperture coefficient Clow (step F4), and determines whether the target aperture coefficient Cref ^* is greater than or equal to the braking aperture coefficient Clow. If it is larger than the braking aperture coefficient Clow, the target aperture coefficient Cref ^* has not decreased to the braking aperture coefficient Clow even if the motor 8 enters the braking state, so a gradual reduction process is performed to reduce the target aperture coefficient Cref ^* . (step F5). On the other hand, if the determined target aperture coefficient Cref ^* is less than or equal to the braking aperture coefficient Clow in step F4, the controller 11 sets the target aperture coefficient Cref ^* as the braking aperture coefficient Clow (step F6).

Further, when the controller 11 determines in step F3 that the motor 8 is not in the braking state but in the powering state, it then determines whether the determination result of the operating state of the motor 8 in the previous calculation cycle is in the braking state. (Step F7). If it is determined in step F7 that the operating state of the motor 8 in the previous calculation cycle is the braking state, the throttle coefficient of the first variable throttle valve 6 is set to the initial value by the gradual reduction process executed when the motor 8 is in the braking state. If it is below, it is necessary to perform an increase process to increase the target aperture coefficient Cref ^* to the initial value Cini. Therefore, the controller 11 determines whether the target aperture coefficient Cref ^* is smaller than the initial value Cini (step F8). If it is determined in step F8 that the target aperture coefficient Cref ^* is less than the initial value Cini, a gradual increase process is performed to increase the value of the target aperture coefficient Cref ^* (step F9). On the other hand, if it is determined in step F8 that the target aperture coefficient Cref ^* is greater than or equal to the initial value Cini, the gradual increase process is not necessary, so the target aperture coefficient Cref ^* is set to the initial value Cini (step F10).

If the controller 11 determines in step F7 that the operating state of the motor 8 in the previous calculation cycle is not a braking state but a power running state, the controller 11 determines whether the motor 8 is in a power running state based on the rotational speed and torque values of the motor 8. It is determined whether the operating point of is in the first quadrant (step F11). If the controller 11 determines that the operating point of the motor 8 is in the first quadrant as a result of the determination in step F11, the controller 11 proceeds to step F12 and determines that the rotational acceleration of the motor 8 is less than 0, and It is determined whether the absolute value of the rotational acceleration is greater than or equal to a threshold value α.

If the controller 11 determines in step F12 that the rotational acceleration of the motor 8 is less than 0 and that the absolute value of the rotational acceleration is equal to or greater than the threshold value α, the controller 11 obtains a zero-cross torque and performs a gradual reduction process to reduce the target throttle coefficient Cref ^* (step F13). If the controller 11 determines in step F11 that the operating point of the motor 8 is in the third quadrant rather than the first quadrant, the controller 11 proceeds to step F14 to determine whether the rotational acceleration of the motor 8 is equal to or greater than 0 and that the absolute value of the rotational acceleration is equal to or greater than the threshold value α. If the controller 11 determines in step F14 that the rotational acceleration of the motor 8 is equal to or greater than 0 and that the absolute value of the rotational acceleration is equal to or greater than the threshold value α, the controller 11 obtains a zero-cross torque and performs a gradual reduction process to reduce the target throttle coefficient Cref ^* (step F13).

In addition, if the controller 11 determines in step F12 that the rotational acceleration of the motor 8 is equal to or greater than 0 or that the absolute value of the rotational acceleration is less than the threshold value α, and if the controller 11 determines in step F14 that the rotational acceleration of the motor 8 is less than 0 or that the absolute value of the rotational acceleration is less than the threshold value α, the controller 11 proceeds to step F15 and sets the target throttle coefficient Cref* to the initial value Cini.

When the setting of the value of the target aperture coefficient Cref ^* is completed, the controller 11 supplies current from the drive circuit 35 to the drive source of the first variable throttle valve 6 so that the aperture coefficient of the first variable throttle valve 6 becomes the target aperture coefficient Cref. Control so that ^* .

The controller 11 repeatedly executes the above process to control the throttle coefficient of the first variable throttle valve 6 so as to increase the regenerative power when the motor 8 is in a braking state.

In addition, except for the drive circuit in the thrust control unit 20, the pressure sensors 25a, 25b in the actual thrust detection unit 25, the drive circuit 35 and the drive circuit in the second control unit 23, the hardware resources of the controller 11 include, although not shown in the figure, an interface for inputting signals of thrust commands, the rotational speed and torque (current) of the motor 8 and the pressure in the cylinder 2, a storage device such as a ROM (Read Only Memory) in which programs used for processing required to control the motor 8, the first variable throttle valve 6 and the second variable throttle valve 7 are stored, an arithmetic unit such as a CPU (Central Processing Unit) that executes processing based on the programs, and a storage device such as a RAM (Random Access Memory) that provides memory space for the CPU. Each part of the thrust control unit 20 and the throttle valve control unit 21 in the controller 11 can be realized by the execution of the programs by the CPU. Additionally, the controller 11 may be realized by an analog electronic circuit, instead of by a CPU executing the program.

As described above, the cylinder device A of this embodiment includes a hydraulic cylinder 1 having a cylinder 2, a piston 3 movably inserted into the cylinder 2 to divide the cylinder 2 into two working chambers R1 and R2, a first flow path 4 and a second flow path 5 that are parallel to each other and communicate the working chambers R1 and R2, a first variable throttle valve 6 provided in the first flow path 4, and a bidirectional discharge pump 9 provided in the second flow path 5 and driven by a motor 8, and a controller 11 that controls the first variable throttle valve 6 and the motor 8. When the motor 8 is in a braking state, the controller 11 controls the throttling coefficient of the first variable throttle valve 6 so as to increase the rotation speed of the motor 8. According to the cylinder device A configured in this manner, when the motor 8 is in a state where it can perform power regeneration, the throttling coefficient of the first variable throttle valve 6 is controlled so as to increase the rotation speed of the motor 8, so that the power regenerated by the motor 8 can be increased and regeneration can be performed more efficiently than in conventional cylinder devices. Therefore, according to the cylinder device A, regeneration power can be improved and regeneration can be performed efficiently.

As described above, in the cylinder device 1 of this embodiment, the regenerative power of the motor 8 is improved by controlling the throttling coefficient of the first variable throttle valve 6. Therefore, in the cylinder device 1 of this embodiment, the second variable throttle valve 7 is provided in series with the pump 9 in the second flow path 5, but the second variable throttle valve 7 may be eliminated, and the effect of the present invention is not lost even if the second variable throttle valve 7 is eliminated. However, when the second variable throttle valve 7 is provided, it is possible to enjoy the advantage that the operating point of the motor 8 can be prevented from being in a load torque region where it is impossible to generate by appropriately controlling the throttling coefficient of the second variable throttle valve 7.

Further, in the cylinder device A of the present embodiment, the controller 11 includes a first filter 30a that removes a component higher than the unsprung resonance frequency of the vehicle from the rotational speed of the motor 8, and a first filter 30a that removes a component higher than the unsprung resonance frequency of the vehicle from the rotational speed of the motor 8. The motor 8 is in a braking state based on the second filter 30b that removes components higher than the frequency, the filtered rotational speed processed by the first filter 30a, and the filtered torque processed by the second filter 30b. a braking state determining unit 31 that determines whether or not there is a braking state; and a throttling coefficient calculating unit that sets the throttling coefficient in the first variable throttle valve 6 to the braking throttling coefficient Clow if the determination result of the braking state determining unit 31 is a braking determination. It is equipped with 34. According to the cylinder device A configured in this way, components higher than the high frequency unsprung resonance frequency are removed from the rotational speed and torque of the motor 8, so that the braking of the motor 8 is performed in accordance with the vibration of the sprung member in the vehicle. The state can be grasped with high accuracy, and the throttle coefficient of the first variable throttle valve 6 can be appropriately controlled.

Furthermore, in the cylinder device A of the present embodiment, the controller 11 includes a rotational acceleration calculation unit 32 that calculates the rotational acceleration of the motor 8 based on the filtered rotational speed, and the aperture coefficient calculation unit 34 is configured to determine the braking state. If the determination result of the section 31 is a power running determination, the operating point of the motor 8 is in the first quadrant, the rotational acceleration is less than 0, and the absolute value of the rotational acceleration is greater than or equal to the threshold α, and When the operating point is in the third quadrant, the rotational acceleration is 0 or more, and the absolute value of the rotational acceleration is more than the threshold α, the first variable throttle is set so as to gradually reduce the flow path of the first variable throttle valve 6. A target throttling coefficient for valve 6 is set. According to the cylinder device A configured in this way, when the motor 8 is about to transition to the braking state, a gradual reduction process is performed to gradually reduce the throttling coefficient of the first variable throttle valve 6 from when it is in the power running state. When the motor 8 transitions to the braking state, the throttling coefficient of the first variable throttle valve 6 is changed to increase the regenerated power of the motor 8, thereby making it possible to efficiently improve the regenerated power.

In addition, in the cylinder device A of this embodiment, the controller 11 has a torque estimation unit 33 that estimates the zero cross torque when the rotation speed of the motor 8 becomes 0 when the motor 8 transitions from a powering state to a braking state, and the throttle coefficient calculation unit 34 calculates a braking throttle coefficient that increases the regenerative power of the motor 8 from the zero cross torque, and calculates a target throttle coefficient for the first variable throttle valve 6 based on the braking throttle coefficient. With the cylinder device A configured in this way, the braking throttle coefficient can be calculated backwards from the zero cross torque of the motor 8 and set to a value that does not change the actual thrust of the hydraulic cylinder 1 when the rotation speed of the motor 8 becomes 0, so that fluctuations in the actual thrust of the hydraulic cylinder 1 can be suppressed even when control is performed to increase the regenerative power while the motor 8 is in a braking state.

Furthermore, in the cylinder device A of this embodiment, when the judgment result of the braking state judgment unit 31 transitions from braking judgment to powering judgment, the throttling coefficient calculation unit 34 gradually increases the throttling coefficient of the first variable throttle valve 6 to an initial value that increases the flow path compared to the throttling coefficient during braking. According to the cylinder device A configured in this manner, when the motor 8 transitions from the braking state to the powering state, a gradual increase process is performed to gradually increase the throttling coefficient of the first variable throttle valve 6 to an initial value suitable for controlling the thrust of the hydraulic cylinder 1 when the motor 8 is in the powering state, so that a sudden change in the throttling coefficient of the first variable throttle valve 6 is mitigated, and thrust fluctuations of the hydraulic cylinder 1 caused by fluctuations in the throttling coefficient of the first variable throttle valve 6 can be suppressed.

In the cylinder device A of the present embodiment, the throttle coefficient calculation unit 34 calculates the throttle coefficient of the first variable throttle valve 6 based on the square of the time that has passed since the start of changing the throttle coefficient of the first variable throttle valve 6. Gradually decrease the aperture coefficient in . According to the cylinder device A configured in this way, in the gradual reduction process, the target aperture coefficient changes in proportion to the square of the time elapsed from the start of the gradual reduction process, so that the change in the target aperture coefficient draws a quadratic curve. When the operating state of the motor 8 changes from the powering state to the braking state, sudden changes in the thrust of the hydraulic cylinder 1 caused by fluctuations in the throttling coefficient of the first variable throttle valve 6 can be alleviated.

In addition, in the cylinder device A of this embodiment, the controller 11 is equipped with a rotational acceleration calculation unit 32 and a torque estimation unit 33, and the throttling coefficient calculation unit 34 obtains information about the operating status of the motor 8 from the rotational acceleration calculation unit 32 and the torque estimation unit 33, and gradually increases the target throttling coefficient of the first variable throttling valve 6 when the operating state of the motor 8 transitions from a braking state to a powering state, and gradually decreases the target throttling coefficient of the first variable throttling valve 6 when the operating state of the motor 8 transitions from a powering state to a braking state. Therefore, even if control is performed to increase the regenerative power of the motor 8, fluctuations in the actual thrust of the hydraulic cylinder 1 can be suppressed, but in order to achieve the object of the present invention of improving the regenerative power of the motor 8, it is sufficient to be able to determine whether the motor 8 is in a braking state in which it can regenerate. Therefore, the controller 11 may only include a braking state determination unit 31 and a throttling coefficient calculation unit 34, and the throttling coefficient calculation unit 34 may control the target throttling coefficient to a predetermined braking throttling coefficient when the operating state of the motor 8 that improves power regeneration is in a braking state, or may control the target throttling coefficient to a braking throttling coefficient that is inversely proportional to the magnitude of the torque at the time when the rotational speed of the motor 8 becomes 0.

Although the preferred embodiment of the present invention has been described in detail above, modifications, variations, and changes are possible without departing from the scope of the claims.

DESCRIPTION OF SYMBOLS 1... Hydraulic cylinder, 2... Cylinder, 3... Piston, 4... First flow path, 5... Second flow path, 6... First variable throttle valve, 7... ...Second variable throttle valve, 8...Motor, 9...Pump, 11...Controller, 30a...First filter, 30b...Second filter, 31...Braking state determination section , 32...Rotational acceleration calculation unit, 33...Torque estimation unit, 34...Aperture coefficient calculation unit, A...Cylinder device, R1, R2...Working chamber

Claims (6)

a hydraulic cylinder including a cylinder, a piston movably inserted into the cylinder to divide the inside of the cylinder into two working chambers, a first flow passage and a second flow passage arranged in parallel to each other and communicating the working chambers with each other, a first variable throttle valve provided in the first flow passage, and a two-way discharge pump provided in the second flow passage and driven by a motor;
a controller for controlling the first variable throttle valve and the motor,
The cylinder device according to claim 1, wherein the controller controls a throttle coefficient of the first variable throttle valve so as to increase a rotation speed of the motor when the motor is in a braking state. The controller includes:
a first filter that removes a component higher than the unsprung resonance frequency of the vehicle from the rotational speed of the motor;
a second filter that removes a component higher than the unsprung resonance frequency of the vehicle from the torque of the motor;
a braking state determination unit that determines whether the motor is in a braking state based on the filtered rotational speed processed by the first filter and the filtered torque processed by the second filter;
and a throttle coefficient calculating unit that sets the throttle coefficient in the first variable throttle valve to a braking throttle coefficient when the determination result of the braking state determining unit is a braking determination. cylinder device. The controller includes:
a rotational acceleration calculation unit that calculates rotational acceleration of the motor based on the filtered rotational speed;
The aperture coefficient calculation unit is configured to determine that the determination result of the braking state determination unit is power running, that the operating point of the motor is in a first quadrant, that the rotational acceleration is less than 0, and that the absolute value of the rotational acceleration is If the operating point of the motor is in the third quadrant, the rotational acceleration is 0 or more, and the absolute value of the rotational acceleration is greater than or equal to the threshold, the flow rate of the first variable throttle valve is The cylinder device according to claim 2, wherein a target throttle coefficient of the first variable throttle valve is set so as to gradually decrease the flow rate. The controller:
a torque estimating unit that estimates a zero cross torque, which is a torque when a rotation speed of the motor becomes zero when the motor transitions from a powering state to a braking state;
4. The cylinder device according to claim 3, wherein the throttle coefficient calculation unit calculates the braking throttle coefficient that increases the regenerative power of the motor from the zero cross torque, and calculates the target throttle coefficient of the first variable throttle valve based on the braking throttle coefficient. 5. The cylinder device according to claim 4, wherein, when a determination result of the braking state determination unit transitions from a braking determination to a powering determination, the throttle coefficient calculation unit gradually increases the throttle coefficient of the first variable throttle valve to change it to an initial value that makes the flow path larger than the braking throttle coefficient. The cylinder device according to claim 3, characterized in that the throttle coefficient calculation unit gradually reduces the throttle coefficient of the first variable throttle valve based on a square of a time that has elapsed since a change in the throttle coefficient of the first variable throttle valve was started.

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