JPS645178B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a hydraulic power source for a hydraulically operated transmission for a vehicle that uses hydraulic pressure for its gear shifting operation, and more particularly to reducing the driving horsepower of the hydraulic power source. In recent years, hydraulically operated transmissions have become extremely popular in automobiles, and various types of transmissions have been proposed. For example, the most common type is CVT, which combines a tricycle converter and an auxiliary transmission, and configures the auxiliary transmission to be switched by hydraulic pressure, and this switching operation is performed via a switching valve that operates manually or automatically.
Continuously variable transmissions, collectively referred to as , have already been proposed. What these hydraulically operated transmissions have in common is that their gear shifting operations are performed via hydraulic pressure, and even if vehicle speed and throttle opening are detected electrically, However, gear switching and speed ratio changes are usually performed via hydraulic pressure. Therefore, such a hydraulically operated transmission has a dedicated hydraulic power source, and drives this hydraulic power source by increasing or decelerating the engine directly from the output shaft or via a gear. However, with this drive method, the pump capacity is designed to supply a sufficient amount of oil during low-speed rotation, so during high-speed rotation, excess oil is discarded via a relief valve, and the hydraulically operated transmission is This was one of the reasons why cars with this engine were generally said to have poor fuel efficiency and poor power performance. Of course, in order to deal with these inconveniences, some prior art has constructed this hydraulic power source as a variable displacement pump and fed back the discharge pressure to keep the generation of surplus discharge flow as low as possible, but the rotational speed of the pump itself still rotates in proportion to the engine's output shaft rotation speed, so the mechanical sliding loss during high-speed rotation could not be improved at all, and the energy saving effect was small even though the structure was complex. Therefore, for example, as disclosed in Japanese Unexamined Patent Publication No. 52-61669 or Japanese Utility Model Application No. 55-112082, the hydraulically operated transmission is controlled to be driven at a constant speed independent of the input shaft rotational speed. It is known to provide a hydraulic power source for a hydraulically operated transmission. Furthermore, the conventional method of driving a pump is to either directly rotate it with the input shaft of a hydraulically operated transmission or to rotate it with a gear having a certain speed ratio. As the outer diameter of the pump becomes larger and the circumferential speed becomes faster, the friction torque also increases, resulting in a large loss of horsepower.Also, when using the latter method, although the outer diameter of the pump can be made smaller, the speed change gear section Due to the addition of transmission loss, the expected effect cannot be obtained,
There is also the drawback that the system becomes larger. Also, no matter which drive method is used, there are major restrictions on where the pump can be installed, and as engine compartments become smaller these days, this restriction on where the pump can be installed becomes one of the obstacles in the design of automobiles. It can be counted. For example, when designing a horizontally mounted FF vehicle, it is desirable to shorten the axial length of the transmission in order to fit it within the specified vehicle width, but with a pump type that is directly rotated by the input shaft, the axial length of the transmission is unavoidable due to the length of the pump unit. The length and space in the direction are taken up. Therefore, for example, as disclosed in Japanese Unexamined Patent Publication No. 52-61669 or Japanese Utility Model Application No. 55-112082, hydraulic pressure for hydraulically operated transmissions that have fewer restrictions on installation location and can be designed to minimize mechanical loss. Also known are those adapted to provide a source. Furthermore, the temperature of the hydraulically operated transmission itself, represented by oil temperature and casing temperature, varies greatly from about -30°C to about +160°C depending on the outside temperature and usage conditions. Temperature changes greatly change the viscosity of the hydraulic oil. For example, at high temperatures, leakage loss from gaps in various parts of the control valve is large, and it is necessary to overcome this loss and maintain the necessary control oil pressure, so make sure the pump capacity is sufficient. Although it is designed to be large, at normal operating temperatures, especially when it is cold immediately after startup, it produces a completely unnecessary amount of discharge, which is discarded by the relief valve instead of being turned into heat. Also, the lower the oil temperature, the better the volumetric efficiency of the pump, and from the synergistic effect of leakage and volumetric efficiency, it can be seen that the lower the oil temperature, the smaller the pump capacity. For this reason, it is also known to provide a hydraulic power source for a hydraulically operated transmission with a variable discharge amount that changes depending on the oil temperature. Furthermore, since the hydraulic power source of conventional hydraulically operated transmissions generates enough supply oil to maintain the line pressure even when the vehicle is stopped, there is a large horsepower loss in this respect. Line pressure is generally regulated according to the vehicle's operating conditions, but when the car is stopped, there is no problem even if the line pressure drops, but the line pressure recovers when starting. It would be good if it could provide sufficient clutch coupling force. For example, when the throttle is returned to decelerate while driving around town, the clutch engagement force is sufficient to match the torque of the engine brake, so there is no need to maintain the line pressure at the high pressure required when the engine is driving the vehicle. It may be lowered to some extent. This can be clearly understood since the engine braking torque is sufficiently lower than the engine output torque. Therefore, for example, as described in Japanese Utility Model Application Publication No. 55-112082, a hydraulic power source for a hydraulically operated transmission has a variable discharge amount that changes the amount of oil supplied depending on the transmission torque of the transmission, and more preferably, the throttle opening. There are also known devices that provide the following. The object of the present invention is to provide a variable displacement hydraulically operated transmission capable of reducing energy loss by further reducing the discharge flow when the throttle is closed and the vehicle is stationary or coasting at a very low speed. Provides hydraulic power source for machines. A further object of the present invention is to provide a hydraulic power source for a hydraulically operated transmission with a variable discharge amount that can reduce energy loss by lowering the discharge flow when a high-speed gear is engaged and the throttle is closed. It's about doing. It may be said that it is meaningless to save the pump's loss when the throttle is closed since the engine brake converts kinetic energy into thermal energy, but saving the pump's loss when the throttle is closed may be meaningless. This is undesirable because it causes an unnecessary rise in oil temperature and increases leakage loss in the system, and it also applies shear to the oil, significantly shortening the oil life. Furthermore, if the energy that should be consumed by the pump during deceleration can be saved somewhere, the overall fuel efficiency can be improved. SUMMARY OF THE INVENTION An object of the present invention is to provide an energy-saving hydraulic power source system for a hydraulically operated transmission that can recover and store a portion of the driving energy of a vehicle during deceleration and draw it out during next cruising or acceleration to drive a pump. be. Furthermore, when starting the engine, battery energy is converted into rotational energy by the starter motor, but on cold mornings, the sliding resistance of the engine and transmission is large, and the viscous resistance of the pump section also increases.
The battery itself also has extremely poor discharge characteristics at low temperatures. Therefore, in such a case, it is better to completely stop the hydraulic power source of the hydraulically operated transmission to reduce the load on the battery as much as possible to improve starting performance. SUMMARY OF THE INVENTION An object of the present invention is to provide a starting system for a vehicle with a hydraulically actuated transmission that allows the hydraulic power source to be turned off while the starter motor is in use. Next, the configuration of the present invention will be explained based on the drawings. Figure 1 is a cross-sectional view of the most common automatic transmission equipped with a torque converter.The output of the engine's crankshaft 1 is transferred to the turbine by turning the pump 3 of the torque converter 2 and fluidly increasing the output torque. Tell 4. The reaction force due to this torque amplification is transmitted to the casing 6 via the stator 5, and for this purpose, a stator shaft 8 is arranged outside and coaxially with the output shaft 9 of the torque converter. This output shaft 9 becomes the input shaft of an auxiliary transmission (not shown) on the right side of the figure. The right end of the pump 3 is connected to a pump drive shaft 11 via a serration 10.
and drives gears 12 and 13 of the gear pump. When driving a pump with such a configuration, the outer diameter of the pump gear 12 cannot be designed to be small because of the shaft 9, stator shaft 8, and drive shaft 11, and the sliding friction resistance between the side surface of the gear and the casing also increases. There were some inconveniences such as the size of the product. The driving horsepower of the pump, which is driven by being mechanically engaged with the output shaft of the engine, shows a gentle upward-sloping curve to the right, as shown by the solid line in FIG. 2, with respect to the engine rotational speed. In this graph, sufficient pump discharge pressure is already being produced when the engine is idling, and the drive horsepower W ₀ at this time can be said to be the originally required horsepower, and the increase in drive horsepower shown at higher rotational speeds. minute is a simple energy loss. However, if we take a closer look at this W ₀ , the capacity of this pump is determined based on the leakage loss in each control valve at high temperatures, so the oil temperature under normal usage conditions is also determined. If you decide to do so, it should be possible to either run a pump with a smaller capacity at the same speed, or a pump with the same capacity to run at a slower speed, so under these usage conditions, the required horsepower will also be It can be set even smaller. Therefore, it can be seen that this required horsepower W ₀ is also not a constant but a variable that increases with oil temperature. The solid line in Figure 2 shows the drive horsepower relative to the normal pump discharge pressure, but in automatic transmissions that include a torque converter, when the torque converter is converting torque, the reaction force of the stator is Depending on the situation, a method of increasing the line is used, and a pump discharge pressure corresponding to the maximum line pressure is always required. If this is not done, the friction coupling means for engaging the gears of the auxiliary transmission will lose the transmission torque and slip when a large torque amplification is being performed, and if this continues for a long time, it will lead to damage on the friction surface. be. When the discharge pressure is increased under automatic control in this way, the pump drive horsepower increases as shown by the dotted line in Figure 2, and in this case, it is also necessary to deliver a discharge amount sufficient to compensate for leakage from each part. There is a driving horsepower W ₀ ′, and any driving horsepower beyond that is loss horsepower. Of course, this required horsepower W ₀ ' is also not a constant but a variable depending on the oil temperature. When driving in a crowded city area, the engine frequently accelerates and decelerates, generating a loss of horsepower along the dotted line each time, resulting in poor fuel efficiency, and the oil temperature rises so badly that the pump capacity increases. The vicious cycle continued over and over again. In the case of an automatic transmission with a torque converter like in this example, the torque converter slips every time you accelerate in the city, causing the pump to run at a higher speed, making the situation even worse. was. FIG. 3 shows an embodiment of the present invention. In the figure, for the sake of simplicity, the gear meshing of the auxiliary transmission is switched by hydraulic operation in which the switching valve is operated manually. Taking a type transmission as an example, the control system for its hydraulic power source is shown. First, the hydraulic system includes an oil pump 16 that sucks oil in an oil tank 14 through a filter 15, pressurizes it, and sends it out, and a lever 1 that connects this discharge pressure to the stator shaft of the torque converter.
7, the regulator valve 18 regulates the line pressure according to the stator reaction force, and this line pressure is connected to the low-speed clutch _C1 , medium-speed clutch _C2 , or high-speed clutch.
A manual valve 19 that selectively leads to _C3 , a torque converter 2 that is located between the engine and the auxiliary transmission and acts to amplify the torque, a check valve 20 that keeps the oil pressure in the torque converter constant, and an auxiliary transmission. It consists of a second check valve 21 that determines the pressure to be sent to lubricate each part of the machine, and a servo piston 22 that switches forward and reverse gears. It is assumed that when each clutch C ₁ , C ₂ , C ₃ enters the operating state, the meshing of the gears in the transmission becomes low speed, medium speed, and high speed, respectively. The oil pump 16 is driven by an electric motor 24 which is rotated by electric energy from a battery 23, either directly or via a reduction gear. Of course, the electrical energy of the battery is supplied to the battery 2 via a voltage regulator 26 from a generator 25 that is rotated by the engine output shaft.
It was stored in 3. A first switch 27 interlocked with the ignition switch is connected between the battery 23 and the motor 24.
A second switch 30 that controls the starter drive circuit 28 and closes when the starter switch 29 is opened, and a speed control means 31 that controls the rotational speed of the motor 24 using various signals are interposed in series. As such speed control means 31, a wiper motor speed control system is popular, and other examples include a current chopper system and the like. The signal delivered to the speed control means 31 is as follows:
Temperature signals 33, 33' generated by the temperature detection element 32 in the oil tank, and position signals 35 generated by position switches 34, 34' indicating that the manual valve 19 is in the N (neutral) or P (parking) position. The high-speed gear signal 37 generated by the hydraulic switch 36, which detects the meshing state of the high-speed gear, and the idle signal 40 generated by the stroke switch 39, which indicates that the throttle pedal 38 is in the idling position, are aligned. A high-speed coasting signal 42 issued by a first AND circuit element 41 that detects and a speedometer 4 that detects that the vehicle speed has become lower than a predetermined reference low speed value.
A low-speed coasting signal 46 is generated by a second AND circuit element 45 that detects that the low-speed signal 44 generated by the detector in 3 and the idle signal 40 are aligned.
and are available. Throttle pedal 38 in the diagram
is rotatably supported on the vehicle body at a pivot point 47, and when the pedal is depressed and displaced as shown by the chain line, wires 48 and the like are pulled to open the engine throttle valve in a known manner. The low speed signal 44 is issued, for example, when the vehicle speed becomes less than 10 km/h, and a known mechanism for generating such a signal is, for example, a 100 km/h alarm switch under current regulations. FIG. 4 shows another embodiment, in which the manual valve 19
The signals generated at the N and P shift positions are configured such that the motor 24 rotates at a certain low speed when it is in the N position, while the motor 24 is completely stationary when it is in the P position. By performing the starting operation at the P position, the electrical load at the time of starting the starter motor is reduced, and the low speed signal 44 detected by the second AND circuit element 45 is the signal generated by the hydraulic switch 49 that detects the engagement of the low gear, and 2 switch 30 is a switch that closes when the engine speed exceeds, for example, 500 rpm; such a detection mechanism may be the same as the aforementioned vehicle speed switch incorporated in the tachometer 50, or a switch that is turned on and off by centrifugal force. Various types of devices are possible, such as those installed on a camshaft or the like. If the line pressure adjusted by the regulator valve 18, which corresponds to the torque ratio (stator reaction force) of the torque converter, exceeds a normal value (for example, 7.5 kg/cm ² ), the amount of oil leaking from each part of the hydraulic system will increase the pressure. Since the pressure increases as the pressure rises, if the pump is driven at the same rotation speed as before, the pressure may not increase as a result. To cope with this, the line pressure pressure sensor 51 provides a high pressure signal 52 to the speed control means 31 to compensate for oil leakage and adjust the desired line pressure when the line pressure is increased above a certain set value. The rotational speed of the motor 24 is increased so that the pressure can be maintained. Next, to explain its operation, in FIG. 3, the starter motor is turned to start the engine, and after the engine is started, the starter switch 29 is turned off, and the switch 30 is turned on, so that the motor 24 can rotate. On the other hand, in FIG. 4, when the engine starts to rotate at an idle speed (for example, Ne=600 rpm) or higher, both the first and second switches 27 and 30 are closed, and the motor 24 becomes rotatable. If the engine does not start at this time, the switch 30 remains open and no current flows to the motor 24. However, as when restarting after warming up, the engine is already warmed up and the battery is 23.
When the battery is fully charged, the rotation speed (500 rpm) at which the second switch 30 closes only by the power of the starter motor
Even if the switch 30 closes and the motor 24 starts rotating before the engine rotates on its own,
It does not cause any inconvenience in light of the purpose. Now, during this startup, the manual valve 19 is always in the N or P position (this is a well-known fact in automatic transmission technology), and the signal 35 is received, so
Since the speed control means 31 drives the motor 24 at a low first speed to lightly drive the rotation pump 16, oil is sent to the torque converter 2 and the inside thereof is filled with oil. At this time, the motor rotation speed is extremely low, and the driving horsepower is kept to a minimum. Note that even if this first speed is 0, it does not pose a big problem in practice. Next, when the manual valve 19 is moved to the left and brought to the "1" position for starting, the pump pressure is sent to the first clutch _C1 via the servo piston 22. At this time, the vehicle speed is 0, so if the throttle pedal is at the idle position indicated by the solid line, the signal 46 will control the speed control means 31 instead of the signal 35, and the motor 24 will be controlled at the above-mentioned first speed or In response to requests such as providing creep characteristics to a vehicle, compensating for pressure oil leakage through the clear balance of many valves in a pressure oil control circuit, or improving responsiveness when starting a vehicle. Drive at a second speed faster than this. Now, when the throttle pedal 38 is depressed in this state, the signal 46 disappears and the motor 24 operates at the second speed if the setting is such that sufficient pump discharge pressure can be obtained, or at the second speed if sufficient discharge pressure cannot be obtained. Driven at a fast third speed, the pump discharge pressure is sufficient to maintain clutch _C1 with sufficient coupling force, and the vehicle starts moving. After the vehicle speed exceeds 10 km/h, even if the throttle pedal 38 is released and the vehicle coasts, the signal 46 will no longer be present and the rotational speed of the pump will not change. When the vehicle speed increases and the manual valve 19 is moved to the "2" position to select the medium speed gear, the pressure of the pump is guided to the clutch _C2 via the servo piston 22 and the meshing of the medium speed gear is completed. While the gears are engaged, the correlation between the operation of the throttle pedal and the rotational speed of the motor 24 is broken. The purpose of this is to prevent the 2nd clutch _C2 from slipping against the gear shift shock when downshifting from 3rd gear to 2nd gear to apply engine braking on the downhill plate. Assuming that the vehicle speed further increases and the manual valve 19 is moved to the "3" position, the pump discharge pressure will be reduced to the clutch C ₃
The meshing of the 3rd gear (TOP) gear is completed.
In this state, when the throttle pedal 38 is returned and held at the idle position, the signal 42 is transmitted to the speed control means 3.
1, the motor 24 is driven at low speed to save electrical energy, and part of the kinetic energy of the vehicle, which acts as an engine brake and is transmitted in the form of heat, is recovered to the battery 23. At this time, the engine (that is, the generator) is undoubtedly driven by the inertia of the car from the tires, and if the amount of charge that exceeds the amount of discharge comes in, as long as there is charge capacity left in the battery, the energy will be reduced. This is because it can be recovered as electrical energy. Of course, by lowering the rotation speed of the motor 24 by one step,
The discharge pressure may fall below the value required to transmit torque during engine braking, but as mentioned above, engine braking torque is much smaller than engine output (driving) torque, so clutch C ₃ It hardly slips and is unlikely to cause damage. Or another half-hearted clutch
As long as C ₃ does not slip, it is a good idea to proactively stop the motor 24 when the throttle is closed to maximize energy savings. At this time, clutch _C3 is rapidly released and idles, and the engine brake has no effect at all, but the engine brake is originally very weak in the top transmission ratio of a hydraulically operated transmission due to the torque converter and overdrive ratio. There is no actual harm. In addition to the above control, signals 33 and 33' also control the speed control means 31, and when the oil temperature in the tank rises, the rotation speed of the motor 24 is increased by one step each time the temperature exceeds one reference value. Rotate quickly to compensate for leakage loss from each part. Of course, the rotational speed may be increased continuously in response to the signal 33'' which changes continuously as the temperature rises. (Figure 4) In this embodiment, a manual three-stage hydraulically operated transmission is used. For example, in the case of a 3- to 4-speed automatic transmission with an automatic switching function, there are an extremely large number of built-in valves, and future leaks are serious at high temperatures.These leaks must be dealt with. If you run a pump that has a capacity that can handle 4 to 5 horsepower, it will quickly eat up 4 to 5 horsepower, resulting in poor power performance and fuel efficiency.This is compounded by the fact that with a torque converter-type automatic transmission, the torque converter slips every time the engine is started. , so the pump loss was large. According to the present invention, it is possible to create an automatic transmission with excellent power performance and fuel efficiency. In this way, according to the present invention, the pump loss is large depending on the throttle opening of the engine. The electric motor that drives the pump, which has a variable discharge amount for the amount of oil supplied to the oil pump, is controlled so that its rotational speed is set low or stopped when the engine throttle opening is closed, making the oil pump unnecessary. It is possible to prevent the generation of excessive hydraulic pressure, minimize energy loss, and by considering the gear ratio or vehicle speed, it is possible to clearly distinguish areas where energy loss should be further reduced and improve drivability. has.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view showing an example of a conventional automatic transmission pump, Fig. 2 is a characteristic curve of driving horsepower (loss horsepower) of this conventional hydraulic power source, and Fig. 3 is a diagram showing an example of the present invention. FIG. 4 is a system diagram showing another embodiment of the present invention. 16... Oil pump, 24... Electric motor.

Claims (1)

[Scope of Claims] 1. A hydraulically operated transmission for a vehicle in which an oil pump for controlling a hydraulically operated transmission is driven by an electric motor, and the rotational speed of the electric motor is variably controlled in accordance with the throttle opening of the engine. A hydraulically operated transmission for a vehicle, characterized in that the rotational speed of the electric motor is controlled to be set low or stopped when the throttle opening of the engine is closed. 2. The hydraulically operated transmission for a vehicle according to claim 1, wherein the rotational speed of the electric motor is controlled to a low speed when the gear ratio of the hydraulically operated transmission is on the high speed side. Machine. 3. The hydraulically operated transmission for a vehicle according to claim 1, wherein the rotational speed of the electric motor is controlled to a low speed when the gear ratio of the hydraulically operated transmission is on the low speed side. Machine. 4. Claim 1, characterized in that the rotational speed of the electric motor is controlled so as to be independent of the throttle opening when the gear ratio of the hydraulically operated transmission is in a medium speed state. Hydraulically operated transmission for the vehicle described. 5. The hydraulically operated transmission for a vehicle according to claim 1, wherein the rotational speed of the electric motor is stopped or set to a low rotational speed when the vehicle speed is lower than a predetermined value.