JP2007271019A - Control device for automatic transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To appropriately perform brake element fastening control of an automatic transmission such as control in uphill start from a hill holding condition during neutral control according fluctuation of friction coefficient of a brake element friction surface due to facing temperature. <P>SOLUTION: Facing temperature of a brake element for hill holding in hill holding control is detected by a temperature sensor arranged to detect temperature of lubricating oil discharged through a friction surface of the brake element. Then, friction coefficient μ is calculated based on facing temperature and differential brake rotation, and fastening fluid pressure (brake fluid pressure) is established based on the friction coefficient μ and differential rotation of brake. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a control device for an automatic transmission, and more particularly to a control device for an automatic transmission that can accurately perform control of supplying hydraulic pressure to a hydraulic servo that engages and operates a brake element of a transmission mechanism.

  In general, an automatic transmission for an automobile includes a torque converter, a transmission mechanism including a planetary gear (planetary gear mechanism), and a plurality of frictional engagement elements that are engaged and operated by a hydraulic servo such as a clutch and a brake. By controlling the supply of working hydraulic pressure to the hydraulic servo by controlling various control valves, selectively engaging multiple frictional engagement elements and switching the power transmission path of the transmission gear mechanism, the gear stage according to the operating state can be changed. It is configured to be obtained automatically.

  When an automobile equipped with such an automatic transmission is depressed in the forward travel range (drive range) and the vehicle is stopped, the clutch for the low speed stage is normally activated and the gear stage is set to the first speed. The engine is idled and a load is applied to the engine via the torque converter. Therefore, to reduce fuel consumption, when the foot brake is depressed in the forward travel range and the vehicle stops, it is possible to reduce the engine load by automatically setting the automatic transmission to the neutral state. Then, since the engagement shock at the next start is large, the slip amount (slip amount) of the clutch for the low speed stage is controlled to perform the slip engagement state, so-called neutral control (also called neutral idle control), It was considered to reduce the engine load.

  In addition, when an automobile equipped with an automatic transmission that performs such neutral control is stopped on an uphill, the clutch is slipped and engaged by the neutral control. Therefore, depending on the slope of the slope, the foot brake force may be weak. There is a risk that the vehicle will fall later. Therefore, control that creates a state in which the vehicle is not lowered backward by mechanically locking the speed change mechanism by engaging and engaging predetermined frictional engagement elements (for example, a brake element and a one-way clutch) when stopping uphill. It was considered to perform control.

In addition, in the automatic transmission, in order to reduce the shift shock due to the variation of the friction coefficient during the shift, the friction coefficient of the brake element is calculated based on the hydraulic oil temperature of the automatic transmission, and the calculated friction coefficient 2. Description of the Related Art Conventionally, a control device for an automatic transmission is configured so that a brake element is controlled to be engaged using a brake (see, for example, Patent Document 1).
JP 2000-154867 A

  One of the parameters that influence the engagement force of the brake element in the automatic transmission is the friction coefficient of the friction surface of the brake element. The friction coefficient of the brake element friction surface varies depending on the fluctuation of the facing temperature (friction surface temperature) of the brake element. Therefore, in the control of the engagement hydraulic pressure of the brake element (the working hydraulic pressure supplied to the hydraulic servo), it is necessary to perform the control in consideration of the fluctuation of the friction coefficient due to the fluctuation of the facing temperature. For example, when setting the fastening hydraulic pressure of a hill hold brake element when performing hill hold control in a neutral control state, the facing temperature of the hill hold brake element is accurately detected, and a friction coefficient that varies depending on the facing temperature is calculated. Appropriately set the brake hydraulic pressure (braking element engagement hydraulic pressure) according to the road surface gradient using the friction coefficient of the brake element friction surface as a parameter so that the stop maintenance (hold) force according to the situation can be realized accurately. Is required. In the automatic transmission that performs both neutral control and hill hold control in this way, the foot brake is returned from the hill hold state during the neutral control particularly when the vehicle starts on a slope, and the forward travel clutch is engaged. It is necessary to precisely control the fastening hydraulic pressure so that the hill hold brake element is released smoothly and quickly and no release shock occurs. It is required to set it as low as possible so that it can be quickly released, and to set it with high accuracy by taking into account the fluctuation of the friction coefficient due to the facing temperature.

  The above-described conventional technique for calculating the friction coefficient of the brake element based on the hydraulic oil temperature of the automatic transmission does not detect the facing temperature of the friction engagement element, but accurately controls the fluctuation of the friction coefficient due to the facing temperature. Can not do.

  It is an object of the present invention to accurately perform brake element fastening control of an automatic transmission, such as control when starting a hill from a hill hold state during neutral control, according to a variation in a friction coefficient of a brake element friction surface due to a facing temperature. There is in doing so.

  The control apparatus for an automatic transmission according to the present invention includes a speed change mechanism capable of selectively realizing a required shift speed in a travel range by switching a power transmission path, and cooperating with the speed change mechanism. A friction engagement element (clutch, brake, etc.) to be switched; a hydraulic servo that engages the friction engagement element; and a hydraulic control device that controls the supply of hydraulic pressure to the hydraulic servo; and at least one of the friction engagement elements One is a control device for an automatic transmission which is a brake element for fixing a predetermined rotating element of the transmission mechanism to a transmission case, and includes a lubricant supply means for supplying lubricant to a friction surface of the brake element, and the lubricant Oil temperature detecting means for detecting the temperature of the lubricating oil supplied and discharged to the friction surface of the brake element by the oil supplying means is provided, and the block is based on the temperature of the discharged lubricating oil. Calculating a friction coefficient of the friction surface of a rk element, in which on the basis of said coefficient of friction configured to control the supply of hydraulic pressure to the hydraulic servo for engagement operation of the brake element.

  In this way, the friction coefficient of the friction surface of the brake element is calculated based on the temperature of the lubricating oil supplied to and discharged from the friction surface of the brake element, and the hydraulic servo that engages and operates the brake element based on the friction coefficient. By controlling the supply of the hydraulic pressure (engagement hydraulic pressure), the brake element engagement control of the automatic transmission can be accurately performed according to the variation of the friction coefficient of the brake element friction surface due to the variation of the facing temperature.

  More specifically, the automatic transmission control device is configured, for example, such that the lubricating oil supply means supplies lubricating oil to the friction surface of the brake element from the radially inner side of the brake element, and The brake element is provided with a lubricating oil discharge path for discharging the lubricating oil supplied to the friction surface of the frictional engagement element by the lubricating oil supply means to the outside of the brake element in the radial direction. It is good to provide the arrangement | positioning facing the outer periphery of the said brake element so that the temperature of the lubricating oil discharged | emitted through an oil discharge path | route may be detected. By doing so, the temperature of the friction surface of the brake element (facing temperature) can be accurately grasped by the temperature of the lubricant oil supplied to the friction surface and discharged, and the brake element engagement control of the automatic transmission Can be accurately performed according to the variation of the friction coefficient of the friction surface of the brake element due to the variation of the facing temperature.

  The control device for the automatic transmission may be configured to calculate a friction coefficient related value related to a friction coefficient of the friction surface of the brake element, and to calculate the friction coefficient based on the friction coefficient related value. it can. Thus, the control is simplified by calculating the friction coefficient of the brake element friction surface based on the friction coefficient related value.

  Then, the control device for the automatic transmission operates hydraulic pressure to a hydraulic servo that engages a friction engagement element that is engaged at a predetermined low speed stage of the traveling range when the vehicle stops in the traveling range and a predetermined condition is satisfied. And a neutral control means for executing neutral control for reducing the engine load by setting the friction engagement element to a predetermined slip engagement state by controlling the friction engagement element, and by engaging the predetermined friction engagement element during the neutral control on the uphill. A hill-hold friction engagement element that includes hill-hold control means that executes hill-hold control that prevents the vehicle from moving backward while the transmission mechanism is locked, and the brake element engages in the hill-hold control during the neutral control. Can be configured.

  In this case, when setting the fastening hydraulic pressure of the hill hold brake element when performing hill hold control in the neutral control state, the fading temperature of the hill hold brake element is accurately detected, and the coefficient of friction varies depending on the facing temperature. It is possible to accurately calculate and maintain a stop-holding (hold) force according to the situation.In particular, when starting on a slope, the foot brake is released from the hill hold state during neutral control, and the forward travel clutch is When fastening, the brake element for the hill hold is released smoothly and quickly, and the engagement hydraulic pressure of the brake element according to the road gradient is set appropriately using the friction coefficient of the friction surface of the brake element as a parameter so that the release shock does not occur. Can be set.

  In the automatic transmission control apparatus, the friction coefficient related value may be a differential rotation (a difference in the number of rotations) between the friction surfaces of the brake element. The friction coefficient of the friction surface of the brake element varies due to the variation in differential rotation between the friction surfaces. The fluctuation characteristics can be obtained in advance. Therefore, the differential rotation can be set as the friction coefficient related value, and the friction coefficient of the brake element friction surface can be calculated based on the difference rotation, thereby simplifying the control.

  The automatic transmission control device may be configured to correct the calculated value of the friction coefficient based on the vehicle travel distance. By doing so, it is possible to cope with changes in the friction coefficient due to oil degradation or the like according to the travel distance.

  In this automatic transmission control device, the brake element may have a multi-plate brake mechanism or a band brake mechanism.

  As described above, the control device for an automatic transmission according to the present invention calculates the friction coefficient of the friction surface of the brake element based on the temperature of the lubricating oil supplied to and discharged from the friction surface of the brake element. By controlling the supply of hydraulic pressure (fastening oil pressure) to the hydraulic servo that engages and operates the brake element based on this, the brake element engagement control of the automatic transmission is controlled by the fluctuation of the friction coefficient of the friction surface of the brake element due to the fluctuation of the facing temperature. It can be done accurately according to.

  The automatic transmission control device is provided with a lubricating oil discharge path so that the lubricating oil is supplied from the radially inner side of the brake element and discharged radially outward, and is discharged through the lubricating oil discharge path. The oil temperature detecting means can be provided so as to be opposed to the outer periphery of the brake element so as to detect the temperature of the lubricating oil to be detected, and by doing so, the brake element is supplied to the friction surface and discharged. The temperature of the friction surface of the brake element (facing temperature) can be accurately grasped by the temperature of the lubricating oil, and the brake element engagement control of the automatic transmission can be changed to the variation of the friction coefficient of the brake element friction surface due to the fluctuation of the facing temperature. It can be done accurately.

  The automatic transmission control device is configured to calculate a friction coefficient related value related to the friction coefficient of the friction surface of the brake element, and to calculate the friction coefficient based on the friction coefficient related value. Can be

  Then, the control device for the automatic transmission operates hydraulic pressure to a hydraulic servo that engages a friction engagement element that is engaged at a predetermined low speed stage of the traveling range when the vehicle stops in the traveling range and a predetermined condition is satisfied. The hill hold control for executing the hill hold control for mechanically locking the speed change mechanism to prevent the vehicle from moving backward in the neutral control state for reducing the engine load by setting the friction engagement element to a predetermined slip engagement state by the control of In that case, when setting the tightening hydraulic pressure of the hill hold brake element when performing hill hold control in the neutral control state, the facing temperature of the hill hold brake element is accurately detected and Accurately calculate the coefficient of friction that fluctuates depending on the temperature, and realize stop maintenance (hold) force according to the situation In particular, when the hill hold starts and the foot brake is released from the hill hold state at the time of neutral control and the clutch for forward running is engaged, the hill hold brake element is released smoothly and quickly, and the release shock Therefore, the engagement hydraulic pressure of the brake element according to the road surface gradient can be appropriately set using the friction coefficient of the brake element friction surface as a parameter.

  The automatic transmission control device can use the differential rotation as the friction coefficient related value and calculate the friction coefficient of the brake element friction surface based on the differential rotation, thereby simplifying the control.

  In addition, the control device of the automatic transmission can cope with a change in the friction coefficient due to oil deterioration or the like according to the travel distance by correcting the calculated value of the friction coefficient based on the travel distance of the vehicle.

  This automatic transmission control device can be applied to any case where the brake element has a multi-plate brake mechanism or a band brake mechanism.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1-7 has shown an example of embodiment of this invention. FIG. 1 is a schematic view showing the overall configuration of an automatic transmission, FIG. 2 is a longitudinal sectional view of a peripheral portion of an oil temperature sensor mounting portion of the automatic transmission, and FIG. FIG. 4 is a characteristic diagram of target braking torque setting in hill hold control, FIG. 5 is a characteristic diagram of multi-plate brake hydraulic pressure setting in hill hold control, FIG. 6 is a characteristic diagram of friction coefficient calculation in hill hold control, and FIG. It is a flowchart which performs hill hold control.

  The overall configuration of the automatic transmission 1 is as shown in FIG. 1. The automatic transmission 1 is arranged around a torque converter 3 to which the output of the engine 2 is input and a turbine shaft 31 that is an output shaft of the torque converter 3, and is driven by the turbine shaft 31. The output of the engine 2 is input from the engine output shaft (crankshaft) 21 to the torque converter 3 and converted by the torque converter 3 via the turbine shaft 31. Friction engaging elements of the gear transmission mechanism 4 (first to third clutches 5, 6, 7 described later, first and second brakes 8, 9 and one-way clutch) are output to the gear transmission mechanism 4. By selectively operating 10) and switching the transmission path of the driving force, 6 forward speeds and 1 reverse speed are obtained. There.

  The torque converter 3 includes a pump (impeller) 33 fixed on the side opposite to the engine in the converter case 32 connected to the engine output shaft 21, and a pump 33 disposed in the converter case 32 so as to face the pump 33. And a stator (blade) which is arranged between the pump 33 and the turbine 34 and supported by the transmission case 11 via a one-way clutch 35 and which increases torque. Vehicle) 36 and a lock-up clutch 37 that is disposed on the engine side in the converter case 32 and allows the engine output shaft 21 and the turbine 34 to be directly connected via the converter case 32. The turbine shaft 31 is connected to the turbine 34 and is rotated by the rotational force of the turbine 34.

  An oil pump 38 is disposed on the opposite side of the torque converter 3 from the engine. The oil pump 38 is connected to the engine output shaft 21 via the pump 33 of the torque converter 3 and the converter case 32, and is driven by the output of the engine 2.

  The gear transmission mechanism 4 includes a first planetary gear mechanism (planetary gear) 41 disposed on the side close to the torque converter 3 in the input shaft direction (axial direction of the turbine shaft 31), and the torque converter 3 in the input shaft direction. A second planetary gear mechanism (planetary gear) 42 disposed on the far side and the second planetary gear mechanism 42 in the input shaft direction at an intermediate position between the first and second planetary gear mechanisms 41, 42. A third planetary gear mechanism (planetary gear) 43 arranged on the near side and a fourth planetary gear mechanism (planetary gear) 44 arranged on the side close to the first planetary gear mechanism 42 in the input shaft direction at the same intermediate position. have.

  The first planetary gear mechanism 41 is disposed around the turbine shaft 31 and is rotatably disposed around the turbine shaft 31, a sun gear 41 a fixed to the transmission case 11, a pinion 41 b meshing with the sun gear 41 a, and the first planetary gear mechanism 41. The pinion carrier 41c rotatably supports the pinion 41b, and the ring gear 41d fixed to the turbine shaft 31 and meshing with the pinion 41b.

  The second planetary gear mechanism (planetary gear) 42 is arranged around the turbine shaft 31, a sun gear 42 a fixed to the transmission case 11, a pinion 42 b meshing with the sun gear 42 a, and the turbine shaft 31. The pinion carrier 42c is rotatably arranged and supports the pinion 42b. The ring gear 42d is fixed to the turbine shaft 31 and meshes with the pinion 42b.

  The third planetary gear mechanism 43 is disposed so as to be rotatable around the turbine shaft 31, a sun gear 43 a rotatably disposed around the turbine shaft 31, a pinion 43 b engaged with the sun gear 43 a, and the turbine shaft 31. A pinion carrier 43c that supports the pinion 43b and a ring gear 43d that is rotatably arranged around the turbine shaft 31 and meshes with the pinion 43b.

  Further, the fourth planetary gear mechanism 44 is disposed rotatably around the turbine shaft 31, a sun gear 44 a rotatably disposed around the turbine shaft 31, a pinion 44 b meshing with the sun gear 44 a, and the turbine shaft 31. A pinion carrier 44c that supports the pinion 44b and a ring gear 43d that is rotatably arranged around the turbine shaft 31 and meshes with the pinion 44b.

  Then, the ring gear 43d of the third planetary gear mechanism 43 and the pinion carrier 44c of the fourth planetary gear mechanism 44 are coupled so as to rotate together, and the pinion carrier 43c of the third planetary gear mechanism 43 and the fourth planetary gear mechanism 43 are connected to each other. A ring gear 44d of the planetary gear mechanism 44 is connected to rotate integrally.

  The automatic transmission 1 includes a wet multi-plate first clutch 5 between the sun gear 44a of the fourth planetary gear mechanism 44 and the pinion carrier 41c of the first planetary gear mechanism 41, and a third A wet-type multi-plate second clutch 6 is provided between the pinion carrier 43c of the planetary gear mechanism 43 and the ring gear 41d of the first planetary gear mechanism 41, and the pinion carrier 42c of the second planetary gear mechanism 42 The third planetary gear mechanism 43 is provided with a third clutch 7 that is a wet multi-plate type between the sun gear 43 a and the third planetary gear mechanism 43, and the third planetary gear mechanism 43 has a third gear 7 between the sun gear 42 a and the transmission case 11. A wet multi-plate first brake 8 that can fix the sun gear 43a of the planetary gear mechanism 43 is provided, and the pinion carrier 43c of the third planetary gear mechanism 43 and the rear of the fourth planetary gear mechanism 44 are provided. The wet type multi-plate type second that allows the pinion carrier 43c of the third planetary gear mechanism 43 and the ring gear 44d of the fourth planetary gear mechanism 44 to be fixed between the integrally connected portion of the gear gear 44d and the transmission case 11. The brake 9 is provided. In addition, the second brake 9 is arranged in parallel between the integrally connected portion of the pinion carrier 43 c of the third planetary gear mechanism 43 and the ring gear 44 d of the fourth planetary gear mechanism 44 and the transmission case 11. A one-way clutch 10 is provided.

  The output gear 12 is connected to the pinion carrier 44 c of the fourth planetary gear mechanism 44. The output of the automatic transmission 1 is transmitted from the output gear 12 to the transmission output shaft 14 via the transmission gear 13, and the left and right axles 18 are transmitted from the transmission output shaft 14 via the transmission gears 15 and 16 and the differential mechanism 17. , 19 is transmitted.

  In the automatic transmission 1, an oil passage (not shown) for passing the lubricating oil in the axial direction is formed inside the turbine shaft 31, and the lubricating oil pressurized by the oil pump 38 is supplied to the hydraulic control device (FIG. It is configured to be pumped into this oil passage via a not-shown) and introduced into the transmission case 11.

  In the automatic transmission 1, the first brake 8 is arranged to be spaced radially inward from the inner peripheral surface of the transmission case 11 as shown in FIGS. 2 and 3. A brake hub 82 that rotates integrally with the sun gear 43a, and a plurality of brake plates 83 and 84 that are alternately arranged in the input shaft direction between the inner peripheral surface of the transmission case 11 and the brake hub 82. .

  A brake piston 85 is inserted into a recess formed in the rear cover 11 a of the transmission case 11, and a pressure receiving chamber 88 is defined between the recess and the brake piston 85. The brake piston 85 is supplied with lubricating oil (hydraulic oil) to the pressure receiving chamber 88 through an oil passage in the turbine shaft 31, and resists the urging force of the return spring 87 according to the hydraulic pressure. Move to (right side of FIG. 2). As a result, the brake plates 83 and 84 are pressed to be in a fastened state. This engaged state is released by stopping the supply of lubricating oil (hydraulic oil) and moving the brake piston 85 to the anti-torque converter side (left side in FIG. 2) by the urging force of the return spring 87.

  Further, a part of the lubricating oil supplied through the oil passage in the turbine shaft 31 passes through a path formed between the transmission elements in the transmission mechanism, and serves as a cooling medium from the inside to the brake plates 83 and 84. Supplied. The transmission case 11 is formed with a lubricating oil discharge path 88 that discharges the lubricating oil supplied to the brake plates 83 and 84 radially outward and allows it to escape in the input shaft direction.

  2 and 3, the transmission case 11 detects the temperature of the lubricating oil discharged through the lubricating oil discharge path 89 at a position facing the outer periphery of the first brake 8. Thus, an oil temperature sensor 101 (oil temperature detecting means) is provided.

  The oil temperature sensor 101 is a sensor that converts temperature into an electric signal, such as a thermocouple or thermistor, and detects the oil temperature of the lubricating oil discharged from the lubricating oil discharge path 88. The lubricating oil discharged from the lubricating oil discharge path 88 is routed through the brake plates 83 and 84, and the oil temperature substantially coincides with the temperature (facing temperature) of the friction surface of the brake plates 83 and 84. Therefore, the facing temperature of the first brake 8 can be accurately detected by detecting the temperature of the lubricating oil with the oil temperature sensor 101.

  Further, the oil temperature sensor 101 is provided at the central portion in the axial direction of the region where the brake plates 83 and 84 are disposed. Therefore, the temperature sensor 101 can detect the temperature of the lubricating oil discharged radially outwardly between the brake plates 83 and 84. In addition, when the amount of heat generated by the brake plates 83 and 84 is generally high, the temperature distribution of the plurality of brake plates 83 and 84 is not uniform, and the brake plates 83 and 84 located on the center side in the rotation axis direction radiate heat. However, even in such a case, the brake plate on the central side that is the highest temperature by the oil temperature sensor 101 is likely to be relatively hot compared to the brake plates 83 and 84 located on both ends. 83 and 84 temperatures can be detected.

  The detection signal of the oil temperature sensor 101 is input to a transmission control unit (not shown). In addition, the transmission control unit receives detection signals from a rotation speed sensor and various sensors provided in the vehicle on which the automatic transmission 1 is mounted, and various types of engine control states and the like from an ECU (engine control unit). Information is entered. The transmission control unit, based on the detection signals from these various sensors and the information on the engine control state from the ECU, supplies the lubricating oil (hydraulic oil) to the hydraulic servo of the first brake 8 and other frictional engagement elements. Various control valves (not shown) of a hydraulic control circuit including a control valve for controlling supply / cutoff and controlling pressure of lubricating oil (operating oil) to be supplied are controlled.

  The hydraulic control circuit that controls the automatic transmission 1 is a pressure regulator valve (PRV) that adjusts the pressure (working oil pressure) of the lubricating oil (working oil) discharged from the oil pump 38 to a predetermined line pressure. Manual valve for switching the range, each friction engagement element of the gear transmission mechanism 4 according to the operation state (first to third clutches 5, 6, 7, first and second two brakes 8, 9 and one way A plurality of shift valves for selectively operating the respective frictional engagement elements by switching the supply state of the lubricating oil (hydraulic oil) to the hydraulic chamber of the clutch 10), and the lubricating oil (hydraulic oil) for the hydraulic chamber of the lockup clutch 37 This is equipped with a control valve for controlling the supply / cutoff of the gas.

  The transmission control unit realizes six forward speeds and one reverse speed by controlling various valves of these hydraulic control circuits, and also enables neutral control and hill hold control.

  Operation of each frictional engagement element (first to third three clutches 5, 6, 7, first and second two brakes 8, 9 and one-way clutch 10) of the gear transmission mechanism 4 of the automatic transmission 1 The relationship between the state, each gear position, neutral idle, and hill hold is as shown in Table 1 below. In the table, “LowC” is the first clutch 5 (Low clutch) and is engaged at the first to fourth speeds on the low speed side. “High C” is the second clutch 6 (High clutch) and is engaged at the fourth to sixth speeds on the high speed side. “3/5 / RC” is a third clutch 7 (3/5 / R clutch) that is engaged at the third speed, the fifth speed, and the reverse speed. “2 / 6B” is a brake (2/6 brake) that is fastened by the first brake 8 at the second speed and the sixth speed. “L / RB” is the second brake 9 (L / R brake) that is engaged at the first speed (only when engine brake is required, such as manual mode or hold mode) and reverse speed. The In the table, ○ indicates the fastening state.

  In this automatic transmission 1, the transmission control unit reduces the engine load when the foot brake is depressed in the forward drive range D (drive) range to stop the vehicle and the engine is idling. In order to improve fuel economy, for example, the slip amount (slip amount) of the first clutch 5 is set so that the engine idle speed is, for example, 600 rpm and the rotational speed of the turbine 34 of the automatic transmission 1 is, for example, about 550 rpm. Is controlled to achieve a predetermined slip engagement state, and at the time of neutral control on the uphill, the first brake 8 is engaged and the one-way clutch 10 is engaged, whereby the transmission mechanism 4 is The hill hold control is performed to prevent the vehicle from moving backward in the locked state.

  In hill hold control, the brake engagement force (target braking torque) necessary to prevent the vehicle from falling backward is set based on the vehicle specifications (weight, etc.) and the road surface gradient, and the brake engagement force is set. Set target engagement hydraulic pressure (multi-plate brake hydraulic pressure) to achieve. As shown in FIG. 4, during the neutral control (N-Idle control), the first brake 8 is engaged and the one-way clutch 10 is engaged while maintaining the engagement hydraulic pressure (target multi-plate brake pressure). Then, the transmission mechanism 4 is brought into the locked state. Then, in this state, when the foot brake is returned (foot brake SWoff) and starts on a slope, the brake engagement force (target braking torque) is reduced so that the first brake 8 is released smoothly and quickly without a shock. The road surface gradient can be obtained from, for example, a balance between the running resistance and the driving force. It is also possible to read the road surface gradient from the data of the navigation system.

  Here, as shown in FIG. 5, the setting of the target engagement hydraulic pressure (multi-plate brake hydraulic pressure) based on the brake engagement force (target braking torque) is performed by the friction of the friction surface of the hill hold brake element (first brake 8). The target engagement hydraulic pressure (multi-plate brake hydraulic pressure) increases as the friction coefficient (brake element μ) decreases with respect to an arbitrary target road gradient (slope stop limit) that varies depending on the coefficient (μ).

  Further, as shown in FIG. 6, the friction coefficient (μ) increases as the discharge temperature, that is, the temperature of the lubricating oil detected by the oil temperature sensor 101 (the facing temperature of the first brake 8) decreases. The smaller the differential rotation between the brake plates 83 and 84 of the first brake 8 (the rotation speed of the brake hub 82 of the first brake 8) is, the smaller it is. Therefore, the differential rotation between the brake plates 83 and 84 of the first brake 8 (the rotation speed of the brake hub 82 of the first brake 8) is separately detected by a rotation speed sensor, and the differential rotation and the oil temperature sensor 101 are A friction coefficient (μ) is calculated based on the detected temperature of the lubricating oil (facing temperature of the first brake 8).

  In this way, the facing temperature of the first brake 8 that is a brake element for hill hold is accurately detected, the friction coefficient (μ) that varies depending on the facing temperature is accurately calculated, and the stop maintaining (hold) force corresponding to the situation is obtained. Can be realized. When the slope starts and the foot brake is released from the hill hold state during the neutral control and the forward travel clutch (first clutch 5) is engaged, the hill hold brake element (first The brake oil pressure of the brake element (first brake 8) according to the road surface gradient is set appropriately using the friction coefficient (μ) of the brake element friction surface as a parameter so that the brake 8) is released smoothly and quickly and no release shock occurs. Can be set to prevent the driver from feeling uncomfortable.

  The specific processing of this hill hold control is as shown in the flowchart of FIG. 7. First, in step S1, various information (vehicle speed, inhibitor switch, brake switch, lubricating oil temperature, clutch oil temperature, clutch differential rotation, brake oil) Temperature, brake differential rotation, travel distance, etc.) are detected, and then in step S2, it is determined whether or not the foot brake switch is on.

  If the foot brake switch is on, the process proceeds to step S3, and a target braking torque capable of stopping on a slope up to an arbitrary target road gradient is set as a function of vehicle specifications (vehicle weight, etc.) and road gradient.

  In step S5, the friction coefficient (μ) of the friction surface of the brake element for the hill hold (first brake 8) is estimated from the map of the brake temperature (oil temperature) and the differential rotation.

  In step S6, the estimated value of the friction coefficient (μ) is corrected based on the travel distance.

  In step S7, a multi-plate brake hydraulic pressure that achieves the target braking torque is set based on the corrected friction coefficient (μ), the target braking torque, and the brake specifications.

  When the foot brake switch is turned off in step S2, the target braking torque (see FIG. 4) at the time of releasing the brake is set in step S4, and the processing of steps S5 to S7 is performed to set the target braking torque. Set the multi-plate brake hydraulic pressure to be realized.

  The present invention is not limited to the automatic transmission of the above embodiment, but can be applied to various other automatic transmissions having different configurations, and is limited to the hill hold control during the neutral control. In general, the present invention can be applied to fastening control of brake elements in general.

It is a mimetic diagram showing the whole automatic transmission composition of the embodiment of the present invention. It is a longitudinal cross-sectional view of the oil temperature sensor attachment part periphery part of the automatic transmission of embodiment of this invention. It is a cross-sectional view of the peripheral portion of the oil temperature sensor mounting portion of the automatic transmission according to the embodiment of the present invention. It is a characteristic view of the target braking torque setting in the hill hold control of the automatic transmission of the embodiment of the present invention. It is a characteristic view of the multi-plate brake oil pressure setting in the hill hold control of the automatic transmission according to the embodiment of the present invention. It is a characteristic view of the friction coefficient calculation in the hill hold control of the automatic transmission of embodiment of this invention. It is a flowchart which performs the hill hold control of the automatic transmission of embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Automatic transmission 4 Gear transmission mechanism 5 1st clutch 6 2nd clutch 7 3rd clutch 8 1st brake 9 2nd brake 10 One-way clutch 11 Transmission case 31 Turbine shaft 41 1st planetary gear mechanism 42 Second planetary gear mechanism 43 Third planetary gear mechanism 44 Fourth planetary gear mechanism 82 Brake hub 83, 84 Brake plate 85 Brake piston 87 Return spring 88 Pressure receiving chamber 89 Lubricating oil discharge path 101 Oil temperature sensor (oil temperature) Detection means)

Claims (8)

A speed change mechanism capable of selectively realizing a required shift speed in a travel range by switching a power transmission path, a friction engagement element that cooperates with the speed change mechanism and switches the power transmission path by an engagement operation, and a friction engagement element A brake including a hydraulic servo for engaging and operating, and a hydraulic control device for controlling supply of operating oil pressure to the hydraulic servo, wherein at least one of the friction engagement elements fixes a predetermined rotating element of the transmission mechanism to a transmission case A control device for an automatic transmission that is an element,
Lubricating oil supplying means for supplying lubricating oil to the friction surface of the brake element and oil temperature detecting means for detecting the temperature of the lubricating oil supplied to the friction surface of the brake element by the lubricating oil supplying means and discharged ,
Calculating the friction coefficient of the friction surface of the brake element based on the temperature of the discharged lubricating oil, and controlling the supply of hydraulic pressure to the hydraulic servo that engages the brake element based on the friction coefficient; A control device for an automatic transmission. The lubricating oil supply means is configured to supply lubricating oil to the friction surface of the brake element from the radially inner side of the brake element,
A lubricating oil discharge path for discharging the lubricating oil supplied to the friction surface of the frictional engagement element by the lubricating oil supply means in the brake element is provided in a radially outward direction of the brake element;
2. The automatic transmission according to claim 1, wherein the oil temperature detecting means is provided so as to face the outer periphery of the brake element so as to detect the temperature of the lubricating oil discharged through the lubricating oil discharge path. Machine control device. 3. The automatic transmission according to claim 1, wherein a friction coefficient related value related to a friction coefficient of a friction surface of the brake element is calculated, and the friction coefficient is calculated based on the friction coefficient related value. Control device. When the vehicle stops in the travel range and a predetermined condition is met, the friction engagement element is controlled to the predetermined slip by controlling the hydraulic pressure to the hydraulic servo that engages the friction engagement element that is engaged at the predetermined low speed stage of the travel range. Neutral control means for executing neutral control for reducing engine load as the engaged state is provided, and a predetermined frictional engagement element is engaged and engaged during the neutral control on an uphill to lock the speed change mechanism into a locked state to cause the vehicle to move backward. The hill hold control means for executing the hill hold control to prevent, wherein the brake element is a friction engagement element for hill hold that is engaged in the hill hold control during the neutral control. 2. The control device for an automatic transmission according to 2 or 3. 5. The control apparatus for an automatic transmission according to claim 3, wherein the friction coefficient related value is a differential rotation between friction surfaces of the brake element. 6. The control device for an automatic transmission according to claim 1, wherein the calculated value of the friction coefficient is corrected based on a vehicle travel distance. The control device for an automatic transmission according to any one of claims 1 to 6, wherein the brake element has a multi-plate brake mechanism. The control device for an automatic transmission according to any one of claims 1 to 6, wherein the brake element has a band brake mechanism.

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