JPH02120565A - Lock-up clutch control device - Google Patents

Abstract

PURPOSE:To decrease the frequency of shock inflicted on a vehicle so as to make riding comfortably by controlling a lock-up clutch to be switched on when the car speed is larger than the set value such as not to be switched off even with the brakes on. CONSTITUTION:The lock-up clutch 6 of a torque converter is switched on when the car speed becomes high, and thereby the driving force transmitting efficiency of an engine is improved. The title device is constructed such that the lock-up clutch 6 is not switched off even with the brakes on when the car speed is higher than a certain speed set in the range of the lock-up clutch 6 being switched on. Accordingly, in case of running at the speed higher than the set speed, the on/off operation of the lock-up clutch 6 generated each time the brake is applied does not take place. Consequently, the vehicle is prevented from receiving shock, so that the riding becomes comfortable. When the car speed is lowered than the set speed, the lock-up clutch 6 in the 'on' state is switched off when the brake is applied, and thereby the engine stall can be avoided.

Description

[Detailed description of the invention] [Industrial application field]

The present invention provides a lock-up clutch used in the torque converter of an automatic transmission.
This invention relates to a lock-up clutch control device for on/off control.

[Conventional technology]

In automatic transmissions equipped with a torque converter, those in which a lock-up clutch (LtJC) is incorporated into the torque converter are becoming mainstream in order to improve the transmission efficiency of driving force from the engine. A lock-up clutch transmits power by mechanically directly connecting the input side and output side of the torque converter when the vehicle speed changes to a predetermined value. This is how it was done. FIG. 2 is a diagram showing a conventional shift schedule. The vertical axis is the throttle opening (θ), and the horizontal axis is the vehicle speed. Curves A, 11, B and C are boundary lines for shifting gears from 1st gear to 2nd gear, 2nd gear to 3rd gear, and 3rd gear to 4th gear. In FIG. 2, the lock-up clutch is set to be on (directly connected state) in the area shaded by dotted lines. The method for determining this area can be determined as appropriate, taking into account the intended use of the vehicle, the driving characteristics that it is desired to provide, and the like. In the example shown in FIG. 2, when the vehicle speed exceeds S', the lock-up clutch is turned on and the throttle opening is θ. In the following cases, the switch is set to turn on when the vehicle speed exceeds the lower speed S0. The boundary of the 9m area determined in this manner is indicated by a dashed line B. Therefore, the part to the right of the -dotted chain line B (high speed side)
The lock-up clutch control device operates so that the lock-up clutch is turned on at this point, and turned off at the left side. However, if you apply spike brakes (2m brakes) while driving with the lock-up clutch on, the tires may lock and the engine may stall. So-called low μ road with low coefficient of friction (〃...
The risk of this was particularly high when the vehicle was traveling at speeds (I2 coefficient). To prevent such a situation, conventional lock-up clutch control devices automatically turn the lock-up clutch off (CM disengaged state) when the lock-up clutch is turned on and the brakes are applied while driving. Ta. The operating procedure is shown below. FIG. 4 is a flowchart illustrating the operation of a conventional lock-up clutch control device. The item numbers ■ to [phase] in the following explanation correspond to steps ■ to [phase] in FIG. 4. ■ Read vehicle speed S and throttle opening θ. The vehicle speed S is obtained from the vehicle speed sensor, and the throttle opening θ is obtained from the throttle opening sensor. ■ The check in this step is that when the read vehicle speed S and throttle opening θ are plotted on the shift schedule in Figure 2, they belong to the region on the right (high speed side) of the -dotted chain line B, but on the left (low speed side) This corresponds to checking whether it belongs to the area of . The case of NO is a case belonging to the left side of the - dotted chain line B. ■ If YES, the case belongs to the right side of the - dotted chain line B. At this time, the lock-up clutch (LUC) is turned on. ■ Read the vehicle speed S when the lock amplifier clutch is turned on. ■ Compare the read vehicle speed S with the vehicle speed S0 regarding the boundary of the dashed-dotted line B. If the vehicle speed is less than S0, turn off the lock-up clutch (proceed to step ■). If the vehicle speed is more than S0, keep the lock-up clutch on. ■ Apply the brakes based on the signal from the brake switch. If not, repeat the process from step ■. ■ After applying the brakes, turn off the lock-up clutch. As mentioned above, this is to avoid the tires locking up and the engine stalling. ■ Input the vehicle speed S after turning off the lock-up clutch. ■ Compare the vehicle speed S with 30. If it is smaller than So, the lock-up clutch can be turned off. The current state is ■. Since the lock-up clutch is in the OFF state, there is no need to do anything.
Go to "End". If it is greater than SO, the lock-up clutch should be turned on, but the brake condition must be satisfied before that. [Phase] Check whether the brake is applied. This check is performed even if the vehicle speed S is greater than 30.
If the brakes are applied, it's a bad idea to turn on the lock amp clutch, but do it to check. If it is engaged, keep the lock-up clutch off and return to step ■. If it is not engaged, return to step ■ and turn on the lock amplifier clutch. Note that conventional literature related to lock-up clutch control devices includes, for example, Japanese Patent Laid-Open Nos. 57-184751 and 58-214057.

[Problem to be solved by the invention]

(Problem) However, the above-mentioned conventional technology has a problem in that the frequency of turning on and off the lock-up clutch increases, giving the driver and passengers discomfort in terms of riding comfort. (Explanation of the problem) The moment the lock-up clutch is turned on and then turned off, the power transmission mechanism changes, so it is inevitable that the vehicle will receive some shock. However, according to the conventional lock-up clutch control device, in the region where the lock-up clutch is turned on (in the example of Fig. 2, the region shaded with dotted lines), the lock-up clutch is turned off every time the brake is applied. It is turned on again when the brake is released. As a result, the frequency with which the lock-up clutch is turned on and off increases, and the frequency with which the vehicle receives shocks also increases. As a result, the driver and passengers inevitably feel uncomfortable in terms of ride comfort. An object of the present invention is to solve the above-mentioned problems.

[Means to solve the problem]

In order to solve the above problem, the lock-up clutch control device of the present invention controls the lock-up clutch that is on so that it will not turn off even if the brake is applied, if the vehicle speed is higher than a set value.

[For production]

The lock-up clutch of the torque converter is turned on when the vehicle speed increases, improving the transmission efficiency of the engine's driving force. In the range in which it is turned on, a certain vehicle speed is set, and if the vehicle speed is at or above the lock-up clutch, the lock-up clutch will not be turned off even when the brake is applied. Therefore, if the vehicle is traveling at a speed higher than the set speed. This eliminates the on/off operation of the clutch, which occurs every time the brake is applied. Accordingly, there is no shock to the vehicle, and the ride becomes more comfortable. When the vehicle speed decreases below the set vehicle speed, even if the lock-up clutch is on, it is turned off when the brake is applied. As a result, engine stall can be properly avoided.

【Example】

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a block diagram of the present invention. In Fig. 1, l is a vehicle speed sensor, 2 is a throttle opening sensor, and 3 is a vehicle speed sensor.
is a brake switch, 4 is a controller, 5 is a clutch actuator, and 6 is a lock-up clutch. The controller 4 includes a vehicle speed sensor 1. Throttle opening sensor 2. Signals are taken in from the brake switch 3 and processed according to a predetermined procedure (described in detail in FIG. 5). And lock amplifier clutch actuator 5
A command is issued to turn the lock-up clutch 6 on (a state in which the input and output of the torque converter are directly connected mechanically) or off (a state in which the torque converter is disengaged). FIG. 3 is a diagram showing a shift scale according to the present invention. The basic control concept of the lock-up clutch control device according to the present invention will be explained with reference to this diagram. In FIG. 3, the symbols correspond to those in FIG. The difference from FIG. 2 is that a second boundary line C regarding on/off of the lock-up clutch is provided on the right side (high-speed side) of the dashed line B. The second boundary line C is determined by the vehicle speed. In FIG. 3, the vehicle speed is S, ζ, but the value of Sl can be determined as appropriate in consideration of the purpose of the vehicle or the driving characteristics that it is desired to have. Note that, in accordance with this, the boundary line indicated by the dashed dotted line B will be referred to as the first boundary line. The control concept of the present invention can be summarized as follows. (1) When the driving state belongs to the region to the right (high speed side) of the second boundary line C, the lock-up clutch is not turned off even if the brake is applied. (2) When the driving condition belongs to the area between the first boundary line B and the second boundary line C (the area shaded with dotted lines in Figure 3), the lock-up clutch is activated when the brake is applied. Turn it off, and keep it on if it doesn't work. By controlling the lock-up clutch based on the above concept, the ronoquan clutch is turned on in the region to the right of the second boundary line C. No more turning off. Therefore, by that much,
The frequency of on/off can be reduced. However, even on the right side of the second boundary line C, there is a suspicion that if the lock-up clutch is not disengaged when braking as in the past, there will be no negative effect on the engine.The reason for this is as follows. It's not as good as a mental device. This is because during the process from when the brakes are applied until the engine stalls, the vehicle speed S decreases due to the brakes, passes through Sl, and enters the area between the first boundary line B and the second boundary line C. This is because the process of entering naturally exists. If the brakes are still applied when the vehicle enters this area, the lock-up clutch will be disengaged.
Engine stall is avoided. FIG. 5 is a flowchart illustrating the operation of the lock-up clutch control device of the present invention. Steps with the same step numbers as in the flowchart of FIG. 4 correspond to the steps of FIG. Therefore, explanation regarding those steps will be omitted. There are two steps that are not included in the flowchart of FIG. 4: ■-1 and ■-2. Therefore, only these will be explained. The process proceeds to step ■-1 at step 1 in Figure 3.
The brake is applied while the vehicle is traveling in an area to the right of boundary line B (lock-up clutch is on). ■-1 Read vehicle speed S. (2) Check whether the vehicle speed is less than or equal to the vehicle speed S that defines the second boundary line C. If YES, that is, the following, it means that it belongs to the h■ area on the left side of the second boundary line C (the dotted diagonal lined side). Therefore, since the brake is applied, proceed to step (3) to disengage the lock-up clutch. No, that is, if the vehicle speed is higher than S1, the lock-up clutch is not turned off. Then, in order to monitor the subsequent state of the brakes and vehicle speed S, the process returns to step (2). In the figure, 1 is a vehicle speed sensor, 2 is a throttle opening sensor, 3 is a brake lever, 4 is a controller, 5 is a lock amplifier clutch actuator, and 6 is a lock up clutch.

【Effect of the invention】

According to the present invention as described above, the frequency with which the lock-up clutch is turned on and off is reduced, so the frequency with which the vehicle receives shocks is also reduced. As a result, the ride becomes more comfortable than before.

Claims (1)

[Claims] A lock-up clutch control device that controls an on-on lock-up clutch so that it does not turn off even if the brake is applied, if the vehicle speed is higher than a set value.