JP2014202337A - Hydraulic control device of transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce influence by supply pressure on the controllability of a hydraulic control device using balance piston type valves.SOLUTION: In a hydraulic control device of a transmission, a supply valve and a discharge valve, which are formed of balance piston type valves, communicate with a hydraulic chamber in which hydraulic pressure is supplied or discharged to vary a transmission gear ratio or transmission torque capacity. A control solenoid valve in the balance piston type valve is configured to vary in the opening according to a controlled variable. The hydraulic control device is equipped with controlled variable setting means for so setting the controlled variable that the opening according to the controlled variable when the supply pressure supplied to a first oil chamber in the balance piston type valve is higher than a predetermined reference pressure becomes smaller than the opening when the supply pressure is low.

Description

  The present invention relates to a hydraulic control device for a transmission in which a gear ratio, a transmission torque capacity, and the like are controlled by hydraulic pressure, and more particularly, a shift configured to control supply and discharge of hydraulic pressure by a balanced piston type solenoid valve. The present invention relates to a hydraulic control device for a machine.

  An example of this type of transmission is described in Patent Document 1. The transmission described in this patent document 1 is a belt-type continuously variable transmission, and each of a driving pulley (primary pulley) and a driven pulley (secondary pulley) around which a belt is wound includes a fixed sheave and its pulley. The movable sheave is configured to change the width of the belt winding groove by approaching or separating from the fixed sheave. A supply valve for supplying the hydraulic pressure of the hydraulic source and a discharge valve for discharging the hydraulic pressure to the drain location are connected to each hydraulic chamber that imparts thrust to the movable sheave.

  Then, by opening the supply valve connected to one pulley (for example, the primary pulley) and supplying hydraulic pressure, the groove width of the primary pulley is narrowed and the belt winding radius is increased, resulting in an upshift. On the other hand, by opening the discharge valve and discharging the hydraulic pressure from the primary pulley, the groove width is widened, the belt winding radius is reduced, and a downshift is caused. On the other hand, if the supply valve connected to the other pulley (for example, the secondary pulley) is opened and the hydraulic pressure is supplied to the secondary pulley, the clamping pressure for clamping the belt increases and the transmission torque capacity increases. By opening the discharge valve and discharging the hydraulic pressure from the secondary pulley, the clamping pressure for clamping the belt is reduced, and the transmission torque capacity is reduced.

  Patent Document 1 discloses a balance piston type solenoid valve that can be used as the supply valve or the discharge valve. This solenoid valve is housed so that a piston integrated with a needle-like or shaft-like valve body can be moved back and forth in the axial direction inside the cylinder part, and in the oil chamber in which the valve body is housed. An inflow port communicated with the high pressure portion and an outflow port communicated with the low pressure portion are formed, and the valve body is closed by being abutted against a valve seat that is an open end of the outflow port on the oil chamber side. It is comprised so that it may be in a state.

  In addition, the oil chamber and the oil chamber on the opposite side of the oil chamber with a piston interposed therebetween (hereinafter referred to as a control oil chamber) are communicated with each other via a communication passage having a control orifice. Further, the control oil chamber communicates with the low pressure portion, and a control solenoid for opening and closing the control oil chamber with respect to the low pressure portion is provided. Therefore, by opening the control solenoid, the hydraulic pressure in the control oil chamber decreases, and as a result, the piston moves backward to the control oil chamber side, the valve body is separated from the valve seat, and the control solenoid is opened. By performing the closing control, the hydraulic pressure of the control oil chamber is increased, the piston moves forward to the valve seat side, the valve body hits the valve seat, the outflow port is sealed, and the valve is closed.

  In the transmission using the above-described balance piston solenoid valve, when the hydraulic pressure in the hydraulic chamber in any pulley is increased or decreased, the control solenoid in the supply valve or discharge valve connected to the hydraulic chamber is energized. Then, opening control is performed, and the control oil chamber is communicated with the low pressure portion. As a result, the hydraulic pressure in the control oil chamber flows out to the low pressure portion through the control solenoid, but the flow rate is limited because the hydraulic pressure in the high pressure portion passes through the control orifice communicated with the control oil chamber. The oil pressure in the control oil chamber is maintained lower than the oil pressure in the oil chamber on the opposite side, and the main valve, which is a valve body integrated with the piston, is maintained in the open state. That is, in the above-described balance piston type solenoid valve, the hydraulic pressure in the control oil chamber is set according to the difference between the amount of hydraulic pressure passing through the control orifice and the amount of hydraulic pressure flowing through the control solenoid.

JP 2011-163508 A

  As described above, in the balanced piston type valve, the control solenoid valve is controlled to open to discharge the hydraulic pressure from the second oil chamber, and the hydraulic pressure flows into the second oil chamber through the control orifice accordingly. The hydraulic pressure in the second oil chamber is maintained at a relatively low pressure according to the difference between the discharge amount and the inflow amount. As the hydraulic pressure in the second oil chamber becomes relatively low in this way, the piston and the valve body integrated therewith move backward, and the balance piston valve is opened. Such a force for moving the piston backward is generated based on a difference in hydraulic pressure and pressure receiving area between the second oil chamber and an oil chamber (hereinafter, referred to as a first oil chamber) in which the valve body is accommodated. However, the oil pressure of the oil pressure source acts on the first oil chamber of the supply valve, and the oil pressure of the oil pressure chamber of the pulley acts on the first oil chamber of the discharge valve. The hydraulic pressure is based on the difference in flow rate between the hydraulic pressure discharged from the hydraulic pressure and the hydraulic pressure supplied via the control orifice. The oil pressure in the first oil chamber, particularly the oil pressure of the oil pressure source, varies greatly depending on the operating state of the vehicle on which the transmission is mounted, but the oil pressure in the second oil chamber depends on the opening of the control solenoid valve. Although it changes in response, it does not change particularly significantly. Therefore, depending on the hydraulic pressure of the hydraulic source, the controllability of the supply valve or the discharge valve composed of the balance piston type valve may be lowered.

  More specifically, the amount of hydraulic pressure discharged from the second oil chamber depends on the opening of the control solenoid valve, whereas the amount of oil passing through the control orifice is the opening diameter of the control orifice. Therefore, the hydraulic pressure in the second oil chamber when the control solenoid valve is controlled to a predetermined opening becomes a predetermined pressure corresponding to the difference between the discharge amount and the inflow amount. On the other hand, the hydraulic pressure of the hydraulic power source, that is, the original pressure of the vehicle changes in accordance with the traveling state of the vehicle. For example, when the vehicle is traveling at a constant speed, the accelerator opening (or the requested drive amount) is relatively low. Since it is small, the hydraulic pressure of the hydraulic power source becomes relatively low, and when starting or overtaking, the accelerator opening is greatly depressed to accelerate, so the hydraulic pressure of the hydraulic power source becomes high. Since the difference between the minimum pressure and the maximum pressure is large, the hydraulic pressure in the first oil chamber may become considerably high.

  Therefore, in general, a transmission and a hydraulic control device are designed and manufactured so as to perform a desired operation in a pressure range with high use frequency. However, since the running state of the vehicle is diverse, the hydraulic pressure of the hydraulic power source may be out of the above pressure range, and in this case, the hydraulic pressure of the first oil chamber becomes high and a balanced piston valve is assumed. The valve may open more than this, and hydraulic overshoot and hunting may occur. In order to avoid this, if the control gain at the time of feedback control of the supply valve and the discharge valve is set to be small, the control responsiveness may be lowered. As described above, in the hydraulic control device described in Patent Document 1 described above, there is a possibility that the controllability is deteriorated or changed due to the fluctuation of the supply pressure, and there is still room for improvement in that respect.

  The present invention has been made paying attention to the above technical problem, and is a transmission that can maintain good controllability even when the hydraulic pressure supplied from a high pressure section such as a hydraulic pressure source fluctuates. An object of the present invention is to provide a hydraulic control device.

  In order to achieve the above object, a first aspect of the present invention provides a supply valve that selectively supplies the hydraulic pressure of a hydraulic source to a hydraulic chamber in which a transmission gear ratio or a transmission torque capacity changes as hydraulic pressure is supplied or discharged. And a discharge valve that selectively discharges hydraulic pressure from the hydraulic chamber, and at least one of the supply valve and the discharge valve has a piston part in which the inside of the cylinder portion that accommodates the piston is movable. The first oil chamber and the second oil chamber are divided into a first oil chamber and a second oil chamber, and the first oil chamber and the second oil chamber communicate with each other via a control orifice, and the inflow port communicated with the high pressure portion and the outflow communicated with the low pressure portion. A port is formed in the first oil chamber, and opens and closes either the inflow port or the outflow port by moving together with the piston based on a pressure difference between the first oil chamber and the second oil chamber. Valve body in front In a hydraulic control apparatus for a transmission, which is constituted by a balance piston type valve provided with a control solenoid valve that is integrated with a piston and that selectively communicates the second oil chamber with a low-pressure portion, the control solenoid valve includes: The opening is changed according to the control amount, and the control amount when the supply pressure supplied to the first oil chamber is higher than a predetermined reference pressure is the control amount when the supply pressure is low. Control amount setting means for setting the control amount so that the opening is smaller than the opening is provided.

  According to a second aspect of the present invention, in the first aspect of the invention, the control solenoid valve is configured to be feedback-controlled based on a deviation between a target pressure and an actual pressure in the hydraulic chamber, and the control amount setting means includes Means for reducing the feedback control gain of the control solenoid valve, means for reducing and correcting a deviation between the target hydraulic pressure of the hydraulic chamber and the detected actual hydraulic pressure, and the target hydraulic pressure of the hydraulic chamber and the detected actual hydraulic pressure, And a means for correcting the control amount determined based on the deviation of the transmission.

  According to a third aspect of the present invention, in the first or second aspect of the invention, the balance piston type valve is a supply valve that selectively supplies hydraulic pressure from a hydraulic source to the hydraulic chamber, and from the hydraulic source to the hydraulic chamber. A hydraulic control apparatus for a transmission, wherein hydraulic pressure is supplied.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, the transmission includes a pair of pulleys around which a belt is wound and has the hydraulic chamber, and the hydraulic chamber of one pulley has a hydraulic pressure. Including a belt type continuously variable transmission in which a transmission ratio is set in accordance with the hydraulic pressure supplied to the hydraulic chamber of the other pulley. It is a hydraulic control device.

  According to the hydraulic control apparatus of the present invention, the hydraulic pressure is discharged from the second oil chamber by opening the control solenoid valve with a predetermined control amount, and the hydraulic pressure is accordingly supplied to the second oil chamber via the control orifice. The hydraulic pressure of the second oil chamber flows into the pressure according to the difference between the hydraulic pressure outflow amount and the inflow amount. Thus, a pressure difference is generated between the first oil chamber and the second oil chamber, and the piston and the valve body move in a direction away from the outflow port or the inflow port to be opened. In this case, the oil pressure in the second oil chamber is a pressure based on the difference between the outflow amount and the inflow amount of the oil pressure, whereas the oil pressure in the first oil chamber is a pressure corresponding to the supply pressure. Therefore, the higher the supply pressure, the greater the pressure difference between the first oil chamber and the second oil chamber. In the hydraulic control device according to the present invention, when the supply pressure to the first oil chamber is higher than the reference pressure, the control amount of the control solenoid valve when the supply pressure is high is smaller than the opening when the supply pressure is low. This is a control amount for setting the opening. Therefore, the pressure difference between the first oil chamber and the second oil chamber when the control solenoid valve is opened is controlled so that the control amount of the control solenoid valve is set as described above even if the supply pressure is high. It is not particularly large because the amount of hydraulic pressure discharged from the chamber is suppressed. In other words, the supply of hydraulic pressure to the hydraulic chamber or the discharge of the hydraulic pressure is not affected by the high supply pressure, or the influence is suppressed, so that stable hydraulic control can be performed.

  In particular, according to the invention of claim 4, since a large hydraulic pressure is required at the time of starting or sudden acceleration, the hydraulic pressure of the hydraulic source is increased, and the supply pressure is increased accordingly. Even if it exists, it becomes possible to control the hydraulic pressure of the hydraulic chamber stably.

It is a flowchart for demonstrating an example of the control performed with the hydraulic control apparatus which concerns on this invention. It is a figure which shows an example of the map which set the relationship between the control gain and supply pressure. 1 is a diagram schematically showing a belt-type continuously variable transmission, a hydraulic control circuit thereof, and a control system that are objects of the present invention. It is a schematic diagram which shows in principle the structure of the balance piston type valve which comprises the supply valve or the discharge valve.

  The transmission targeted in the present invention is a transmission whose transmission ratio and transmission torque capacity are controlled by hydraulic pressure. Therefore, the transmission in this invention is a conventionally known stepped transmission or continuously variable transmission for vehicles. It may be a machine. Among them, the transmission whose hydraulic pressure variation immediately affects the gear ratio is a belt-type or toroidal-type continuously variable transmission, and therefore the present invention is suitable for a hydraulic control device for these continuously variable transmissions. Can be applied to.

  FIG. 3 schematically shows a belt type continuously variable transmission and a hydraulic circuit for setting the gear ratio and belt clamping pressure. The belt type continuously variable transmission 1 includes a driving pulley (primary pulley) 2 to which torque of a driving force source (not shown) such as an engine is transmitted, and an output member (not shown) such as an output shaft and an output gear. A belt 4 is wound around a driven pulley (secondary pulley) 3 that outputs torque, and the torque is transmitted between the pulleys 2 and 3 via the belt 4. Each of the pulleys 2 and 3 is configured to be able to change the width of the belt groove around which the belt 4 is wound. Specifically, the primary pulley 2 approaches and separates from the fixed sheave 2A and the fixed sheave 2A. The movable sheave 2B is moved to the fixed sheave 2A side by the hydraulic pressure supplied to or discharged from the hydraulic chamber 2C provided on the back side of the movable sheave 2B. Alternatively, it is configured to be separated from the fixed sheave 2A. Similarly, the secondary pulley 3 is constituted by a fixed sheave 3A and a movable sheave 3B arranged so as to be able to approach and separate from the fixed sheave 3A, and is provided on the back side of the movable sheave 3B. The movable sheave 3B is moved to the fixed sheave 3A side or separated from the fixed sheave 3A by the hydraulic pressure supplied to or discharged from the hydraulic chamber 3C. The belt 4 is sandwiched between the sheaves 3A and 3B by the hydraulic pressure supplied to the hydraulic chamber 3C of one of the pulleys (for example, the secondary pulley 3), and the belt 4 and the sheaves 3A and 3B are sandwiched by the clamping pressure. A transmission torque capacity corresponding to the frictional force is set. In this state, each pulley of the belt 4 is changed by changing the interval (groove width) between the sheaves 2A and 2B by supplying or discharging the hydraulic pressure to the hydraulic chamber 2C of the other pulley (for example, the primary pulley 2). The wrapping radius with respect to 2 and 3 is changed to cause a shift.

  The hydraulic pressures of the hydraulic chambers 2C and 3C in the pulleys 2 and 3 are configured to be controlled by appropriately supplying and discharging the hydraulic pressure. The original pressure is the hydraulic pressure of a hydraulic source 5 such as an oil pump or an accumulator. When an oil pump is used as the hydraulic source 5, the oil pump is a so-called mechanical oil pump or motor driven by the driving force source. It may be an electric oil pump that is driven. A supply oil passage (or line pressure oil passage) 7 communicated with the hydraulic power source 5 through the check valve 6 is communicated with each of the hydraulic chambers 2C and 3C and communicated with the hydraulic chamber 2C of the primary pulley 2. A supply valve 8 is provided in the supply oil passage 7, and the supply valve 8 is controlled to be opened and closed, whereby the hydraulic pressure is supplied to the hydraulic chamber 2 </ b> C and the supply of the hydraulic pressure is shut off. Similarly, a supply valve 9 is provided in the supply oil passage 7 communicated with the hydraulic chamber 3C of the secondary pulley 3, and the supply valve 9 is controlled to open and close to supply hydraulic pressure to the hydraulic chamber 3C. Is configured to shut off the supply. Further, a discharge valve 10 communicates with the hydraulic chamber 2C of the primary pulley 2. By controlling the opening and closing of the discharge valve 10, the hydraulic pressure is discharged from the hydraulic chamber 2C to a predetermined drain location, and the discharge of the hydraulic pressure is shut off. Is configured to do. Similarly, a discharge valve 11 is communicated with the hydraulic chamber 3C of the secondary pulley 3. By controlling the discharge valve 11, the hydraulic pressure is discharged from the hydraulic chamber 3C to a predetermined drain location. It is configured to shut off the discharge of hydraulic pressure.

  The supply valves 8 and 9 and the discharge valves 10 and 11 are electrically controlled solenoid valves that are controlled to open and supply and discharge hydraulic pressure, but are themselves valves without a pressure regulating function. is there. Therefore, the supply valves 8 and 9 and the discharge valves 10 and 11 are feedback-controlled based on the pressure deviation between the target pressure and the actual oil pressure, so that the oil pressure in the hydraulic chambers 2C and 3C is controlled to the target oil pressure. It is configured. Various sensors for obtaining data for the control are provided. For example, a line pressure sensor 12 that detects a line pressure Pl that is a source pressure and outputs a signal, and a hydraulic chamber 2C of the primary pulley 2 is provided. A primary hydraulic sensor 13 for detecting the hydraulic pressure Ppri and outputting a signal, and a secondary hydraulic sensor 14 for detecting the hydraulic pressure Psec of the hydraulic chamber 3C of the secondary pulley 3 and outputting the signal are provided. Further, a primary rotational speed sensor 15 that detects the rotational speed Npri of the primary pulley 2 and outputs a signal, and a secondary rotational speed sensor 16 that detects the rotational speed Nsec of the secondary pulley 3 and outputs a signal are provided. .

  An electronic control unit (ECU) 17 for controlling the supply valves 8 and 9 and the discharge valves 10 and 11 is provided. The electronic control unit 17 is mainly composed of a microcomputer, performs computations using various input data and data stored in advance, and outputs the computation results as control command signals. It is configured. Therefore, the electronic control unit 17 includes data detected by the sensors 12 to 16, that is, the line pressure Pl, the hydraulic pressure Ppri of the hydraulic chamber 2C of the primary pulley 2, the hydraulic pressure Psec of the hydraulic chamber 3C of the secondary pulley 3, The rotational speeds Npri and Nsec of the pulleys 2 and 3 are input.

  In the hydraulic control apparatus according to the present invention, at least one of the supply valve and the discharge valve is constituted by a balance piston type valve. In the hydraulic circuit shown in FIG. , 11 are constituted by balanced piston type valves. In the example shown in FIG. 3, each balance piston type valve has the same configuration, and the configuration will be described with reference to FIG. In the following description of the balance piston type valve, the hydraulic source 5 or the line pressure Pl for the supply valves 8 and 9 is the high pressure section, the hydraulic chambers 2C and 3C are the low pressure section, and the hydraulic chamber 2C and the discharge valves 10 and 11 are the hydraulic chamber 2C, 3C is described as a high pressure part, and a drain location is described as a low pressure part.

  In FIG. 4, a piston 22 integral with the valve body 21 is accommodated inside a cylinder portion 23 so as to be movable back and forth. Therefore, the inside of the cylinder portion 23 is partitioned into two oil chambers 24 and 25 by the piston 22, and the oil chamber 24 in which the valve body 21 is accommodated is included in the oil chamber 24 and 25. An inflow port 27 to which hydraulic pressure is supplied and an outflow port 29 through which the hydraulic pressure flows out toward the low pressure portion 28 are formed. The outflow port 29 is formed in the end plate portion on the distal end side of the valve body 21 so that the outflow port 29 is closed when the valve body 21 abuts and the outflow port 29 is opened when the valve body 21 is retracted. It is configured. Further, a spring 30 that presses the piston 22 toward the outflow port 29 is disposed in the oil chamber 25 on the opposite side of the piston 22 with respect to the oil chamber 24 in which the valve body 21 is accommodated. A port 31 is formed. The signal pressure port 31 and the inflow port 27 are communicated with each other by a communication path 33 having a control orifice 32. The control orifice 32 is for restricting the flow rate by restricting the pressure oil flowing from the high pressure portion 26 or the oil chamber 24 toward the oil chamber 25, and for example, a thin plate material having a minute through hole, It is formed so as to cross the communication path 33. The communication passage 33 is mainly for communicating the oil chambers 24 and 25, and therefore may be formed so as to penetrate the piston 22 in the axial direction or the inner surface of the cylinder portion 23. It may be formed.

  Further, a control solenoid valve 34 for selectively communicating the oil chamber 25 in which the spring 30 is disposed with the low pressure portion 28 is provided. More specifically, an outflow port 35 is formed in the oil chamber 25, and a control solenoid valve 34 is connected to the outflow port 35. The control solenoid valve 34 includes an electromagnetic coil 38 that generates an electromagnetic force that pushes the valve body 36 axially by a spring 37 and pulls the valve body 36 axially against the spring 37. Yes. The present invention can also be applied to a hydraulic control device using a so-called normally open type valve. Therefore, the valve body 36 is pulled back in the valve opening direction by the elastic force of the spring 37, and the electromagnetic force is converted to the elastic force. It may be configured to act on the valve body 36 so as to counteract the above.

  Further, an inflow port 39 communicating with the outflow port 35 is formed on the distal end side of the valve body 36, and the opening end of the inflow port 39 is a valve seat, and the distal end of the valve body 36 is at the open end. The inflow port 39 is hermetically sealed when the parts abut against each other, and the inflow port 39 is opened when the valve body 36 is separated, and the degree of opening according to the amount of current supplied to the electromagnetic coil 38 is set. ing. Furthermore, the outflow port 40 which connects the location in which the valve body 36 is accommodated to the low voltage | pressure part 28 is formed.

The operation of the balance piston type valve will be described. First, the axial force acting on the piston 22 and the valve body 21 integrated therewith is as follows. The force acting in the right direction in FIG. 4 is generated by the oil pressure Ps of the oil chamber 25 (hereinafter also referred to as the second oil chamber) in which the signal pressure port 31 is formed, and the pressure receiving area in the piston 22. Is As, the axial force directed to the right is “Ps × As”. Further, since the forces acting in the left direction in FIG. 4 are the oil pressure Pl of the high pressure portion 26 and the oil pressure Pr of the low pressure portion 28, assuming that the respective pressure receiving areas are Am and Ar, the axial force directed in the left direction is “P1 × Am + Pr × Ar”. The pressure receiving area Am on which the hydraulic pressure Pl of the high pressure portion 26 acts is an area obtained by subtracting the cross sectional area of the valve body 21 from the cross sectional area of the piston 22, and the pressure receiving area Ar on which the hydraulic pressure Pr of the low pressure portion 28 acts is almost equal. It is a cross-sectional area of the outflow port 29. If the right direction in FIG. 4 is a negative direction and the elastic force of the spring 30 is ignored, the axial force acting on the piston 22 and the valve body 21 integrated therewith is
−Ps × As + Pl × Am + Pr × Ar
It becomes. Therefore, when the control solenoid valve 34 is energized and controlled to open, the hydraulic pressure Ps of the second oil chamber 25 is lowered, and the piston 22 moves to the second oil chamber 25 side. Along with this, the valve body 21 opens away from the open end (that is, the valve seat) of the outflow port 29. That is, pressure oil flows from the high pressure portion 26 to the low pressure portion 28.

  The hydraulic pressure Ps of the second oil chamber 25 when operating in this way is the amount of pressure oil Qc supplied from the high pressure section 26 to the second oil chamber 25 through the control orifice 32 and the control solenoid valve 34. It is proportional to the difference (Qc−Qs) from the amount Qs of pressure oil discharged to the low pressure section 28. Of these flow rates, the flow rate Qc of the pressure oil flowing from the high pressure portion 26 to the second oil chamber 25 is a flow rate restricted by the control orifice 32. Further, the flow rate Qs of the pressure oil flowing from the second oil chamber 25 to the low pressure portion 28 becomes a flow rate according to the opening degree of the control solenoid valve 34, and the pressure at which the hydraulic pressure in the second oil chamber 25 is low according to the difference between both flow rates. become. On the other hand, since the opening diameter of the control solenoid valve 34 is constant, the amount of pressure oil flowing therethrough is almost constant. If the flow rate is affected, the difference in pressure between both sides across the control orifice 32, In particular, it is affected by the supply pressure from the high pressure section 26. That is, when the supply pressure is higher than the pressure assumed in design, the flow rate of the hydraulic pressure passing through the control orifice 32 increases.

  Therefore, the hydraulic control apparatus according to the present invention executes the following control in order to stably control the hydraulic pressure in the hydraulic chambers 2C and 3C described above even when the supply pressure changes to high or low. It is configured. An example of the control is shown in the flowchart of FIG. The supply valves 8 and 9 and the discharge valves 10 and 11 constituted by the balance piston type valve having the configuration shown in FIG. 4 obtain the target pressures of the hydraulic chambers 2C and 3C, which are control target portions, Feedback control is performed so that the hydraulic pressure (control pressure) becomes the target pressure. For example, if the control pressure is lower than the target pressure, the supply valves 8 and 9 are controlled to open, and the hydraulic pressure of the hydraulic source 5 is supplied to the hydraulic chambers 2C and 3C. Further, if the control pressure is higher than the target pressure, the discharge valves 10 and 11 are controlled to be opened and discharged from the hydraulic chambers 2C and 3C. The control amount in each case is obtained based on the pressure deviation between the target pressure and the control pressure and a predetermined control gain.

  In performing such feedback control, the routine shown in FIG. 1 is repeatedly executed every predetermined short time. First, the target pressure Po, the control pressure Pr, and the supply pressure Pl are calculated (steps S1, S2, S3). ). The calculation of these data may be performed in the order shown in FIG. 1, may be performed in a different order, or may be performed in parallel. The target pressure P0 is a hydraulic pressure for setting a target gear ratio for the hydraulic chamber 2C of the primary pulley 2, and the target gear ratio is the optimum for the required driving amount such as the accelerator opening, the vehicle speed, and the driving force source. Therefore, the target hydraulic pressure Po for the hydraulic chamber 2C of the primary pulley 2 can be determined based on the target gear ratio, the ratio of axial thrusts of the primary pulley 2 and the secondary pulley 3, and the like. be able to. The hydraulic pressure in the hydraulic chamber 3C of the secondary pulley 3 is a hydraulic pressure that generates a belt clamping pressure and is used to set a transmission torque capacity. Can be based on. The control pressure Pr and supply pressure Pl may be values detected by sensors.

  Next, the control gain Pfb is obtained (step S4). The control gain Pfb is a coefficient of a proportional term, a differential term or an integral term in the feedback control, and is set in advance in the form of a map or the like so as not to cause a control response delay in particular and to prevent control hunting. In the hydraulic control apparatus according to the above, the control gain Pfb is set to a value corresponding to the supply pressure Pl and the control pressure Pr. Specifically, as shown in FIG. 2, the control gain Pfb for the supply valves 8 and 9 is set based on the supply pressure Pl. If the supply pressure Pl is equal to or less than a predetermined reference pressure Pth, a predetermined value is set. When the reference pressure Pth is exceeded, the value is set to a value that decreases as the supply pressure Pl increases. Here, the reference pressure Pth is an upper limit value of a range determined as a frequently used pressure range by design, and an upper limit value of a pressure range in which hydraulic control can be performed without causing any trouble with a normally used control gain. Value. Therefore, when the supply pressure Pl exceeds the reference pressure Pth, the pressure difference between the first oil chamber 24 and the second oil chamber 25 when the control solenoid valve 34 is controlled to open by a predetermined amount is larger than expected. Therefore, the control gain is reduced in order to reduce the control amount of the control solenoid valve 34 so as to eliminate or correct such an excessive pressure difference. Therefore, the amount of control gain reduction, the gradient of decrease, and the like can be obtained in advance based on experiments and prepared as data such as a map. Further, the control gain may be configured to decrease stepwise instead of continuously decreasing as shown in FIG. In addition, the control gain for the discharge valves 10 and 11 may be configured to decrease as the hydraulic pressure increases when the hydraulic pressure in the hydraulic chambers 2C and 3C exceeds the reference pressure.

  On the other hand, a pressure deviation DP (= P0−Pr) is calculated from the target pressure P0 and the control pressure Pr (step S5). Based on the pressure deviation DP and the control gain Pfb, the control amount Isolu of the supply valves 8 and 9 is calculated (step S6), or the control amount Isold of the discharge valves 10 and 11 is calculated (step S7). ). These control amounts Isolu and Isold are, for example, current values, and the relationship between the current value and the opening (or opening diameter) is determined by the configuration of the control solenoid valve 34. Therefore, the relationship is prepared in advance as an arithmetic expression or a map. Can be kept. Therefore, the control in step S6 or step S7 can be calculated from the map using, for example, the control gain Pfb and the pressure deviation DP as arguments. The parameters for calculating the control amount require the control gain Pfb and the pressure deviation DP as described above. However, a shift mode such as a manual mode or an automatic mode is added to the parameters, and a running mode such as a sport mode or a normal mode is added. Modes may be added. That is, correction such as giving priority to control responsiveness or giving priority to control stability may be added.

  Then, the control amounts Isolu, Isold calculated in Step S6 or Step S7 are output as control command signals (Step S8), and the supply valves 8, 9 or the discharge valves 10, 11 correspond to the control amounts Isolu, Isold. The opening is controlled. More specifically, the control solenoid valve 34 in the balance piston type valve constituting each of the supply valves 8 and 9 and the discharge valves 10 and 11 is energized, and the control solenoid valve 34 opens according to the current. .

  In this case, if the supply pressure Pl is higher than the reference pressure Pth, the control gain Pfb is reduced according to the supply pressure Pl as described above, so that the current value of the supply pressure Pl is relatively low. Reduced compared to low case. Therefore, the opening degree of the control solenoid valve 34 becomes smaller when the supply pressure Pl is high, so that even if the hydraulic pressure in the first oil chamber 24 increases in accordance with the supply pressure Pl, the opening from the second oil chamber 25 is reduced. The amount of exhaust pressure is reduced, and the decrease in hydraulic pressure is suppressed. As a result, the pressure difference between the first oil chamber 24 and the second oil chamber 25 is set to a pressure difference when the supply pressure Pl is equal to or lower than the reference pressure Pth, or a pressure difference close thereto, so that the supply valve 8, It is avoided or suppressed that the opening degree of 9 increases more than expected. In other words, the hydraulic pressure is controlled as designed. This is the same when the hydraulic pressure is discharged from the hydraulic chambers 2C and 3C through the discharge valves 10 and 11 if the discharge valves 10 and 11 are constituted by the above-described balance piston type valves. As a result, according to the hydraulic control apparatus according to the present invention, even if the hydraulic pressure on the upstream side of the supply valves 8 and 9 and the discharge valves 10 and 11 (so-called high pressure hydraulic pressure) increases, the influence is particularly affected. Therefore, the hydraulic pressure in the hydraulic chambers 2C and 3C can be controlled, and the controllability of the hydraulic pressure of the transmission is maintained in a good state.

  The supply pressure in the present invention is the hydraulic pressure upstream of the supply valve and the discharge valve, and the present invention controls the control amount of the supply valve and the discharge valve when the supply pressure is higher than a predetermined reference pressure. May be configured to set a small opening as compared with the case where the supply pressure is low. Therefore, in order to reduce the control amount, in addition to reducing the feedback gain described above, the control amount (pressure deviation) is corrected and reduced, or the control amount obtained based on the control deviation and the control gain is reduced. It is also possible to correct the decrease. Further, in the present invention, it is not necessary that all of the supply valves 8 and 9 and the discharge valves 10 and 11 are constituted by the balance piston type valve, and at least one of the supply valves 8 and 9 and the discharge valves 10 and 11 is not required. One should just be comprised by the balance piston type valve | bulb. Therefore, the functional means for executing the control in step S4 shown in FIG. 1 corresponds to the control amount setting means in the present invention.

  Furthermore, the present invention can also be applied to a hydraulic control device using a so-called normally open type valve. Therefore, “reducing the controlled variable” in the above-described specific example means that the opening degree is reduced. However, in the case of a normally open type valve, the current may be increased.

  DESCRIPTION OF SYMBOLS 1 ... Belt type continuously variable transmission, 2 ... Drive pulley (primary pulley), 3 ... Driven pulley (secondary pulley), 4 ... Belt, 2A ... Fixed sheave, 2B ... Movable sheave, 2C ... Hydraulic chamber, 3A ... Fixed sheave 3B ... movable sheave, 3C ... hydraulic chamber, 5 ... hydraulic power source, 7 ... supply oil passage (or line pressure oil passage), 8 ... supply valve, 9 ... supply valve, 10 ... discharge valve, 11 ... discharge valve, 12 DESCRIPTION OF SYMBOLS ... Line pressure sensor, 13 ... Primary oil pressure sensor, 14 ... Secondary oil pressure sensor, 15 ... Primary rotation speed sensor, 16 ... Secondary rotation speed sensor, 17 ... Electronic control unit (ECU), 21 ... Valve body, 22 ... Piston, 23 ... Cylinder part, 24, 25 ... Oil chamber, 26 ... High pressure part, 27 ... Inflow port, 28 ... Low pressure part, 29 ... Outlet port, 31 ... Signal pressure port, 32 ... Control orifice, 33 ... Communication path, 34 ... Control solenoid valve, 35 ... Outlet port, 36 ... Valve body, 37 ... Spring, 38 ... Electromagnetic coil, 39 ... Inlet port, 40 ... Outlet port.

Claims (4)

There are a supply valve for selectively supplying the hydraulic pressure of the hydraulic source to a hydraulic chamber whose transmission gear ratio or transmission torque capacity is changed by supplying or discharging the hydraulic pressure, and a discharge valve for selectively discharging the hydraulic pressure from the hydraulic chamber. At least one of the supply valve and the discharge valve is communicated, and the inside of the cylinder portion that accommodates the piston so as to be movable back and forth is partitioned into a first oil chamber and a second oil chamber by the piston. The first oil chamber and the second oil chamber communicate with each other via a control orifice, and an inflow port communicated with the high pressure portion and an outflow port communicated with the low pressure portion are formed in the first oil chamber, A valve body that opens and closes either the inflow port or the outflow port by moving together with the piston based on a pressure difference between the chamber and the second oil chamber is integrated with the piston, and the second oil chamber is For low pressure part In the hydraulic control device for a transmission control solenoid valves for communicating the 択的 it is constituted by a balance piston valve provided,
The control solenoid valve is configured to change the opening according to the control amount,
The control amount is set so that the control amount when the supply pressure supplied to the first oil chamber is higher than a predetermined reference pressure is smaller than the opening when the supply pressure is low. A hydraulic control apparatus for a transmission, comprising control amount setting means for performing transmission. The control solenoid valve is configured to be feedback controlled based on a deviation between a target pressure and an actual pressure in the hydraulic chamber,
The control amount setting means includes means for reducing a feedback control gain of the control solenoid valve, means for reducing and correcting a deviation between a target hydraulic pressure of the hydraulic chamber and a detected actual hydraulic pressure, and a target hydraulic pressure of the hydraulic chamber. 2. The hydraulic control apparatus for a transmission according to claim 1, further comprising: means for correcting the control amount obtained based on a deviation from the detected actual hydraulic pressure. The balance piston valve is a supply valve that selectively supplies hydraulic pressure from a hydraulic source to the hydraulic chamber,
The hydraulic control device for a transmission according to claim 1 or 2, wherein hydraulic pressure is supplied from the hydraulic source to the hydraulic chamber.   The transmission includes a pair of pulleys around which a belt is wound and which has the hydraulic chamber. The transmission changes the transmission ratio by supplying or discharging the hydraulic pressure to the hydraulic chamber of one pulley and the hydraulic pressure of the other pulley. 4. The transmission hydraulic control apparatus according to claim 1, further comprising a belt type continuously variable transmission in which a transmission torque capacity is set in accordance with the hydraulic pressure supplied to the chamber.

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