JP3463707B2 - Electric vehicle braking system - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a braking system for an electric vehicle, and more particularly to a braking system for an electric vehicle including a regenerative braking device and a mechanical braking device. 2. Description of the Related Art Conventionally, as a braking system for braking an electric vehicle, a mechanical braking device provided with a brake booster for boosting the depression force of a brake pedal, and an operation state of the brake pedal are detected. There is known a sensor including a sensor and a regenerative braking device for increasing or decreasing a regenerative braking force in accordance with an increase or a decrease in an operation amount of a brake pedal detected by the sensor (Japanese Patent Laid-Open No. 2-123902). In order to detect the operation state of the brake pedal, a depression force of the brake pedal and a brake fluid pressure that increases or decreases in accordance with the depression force are detected, or a stroke amount of the brake pedal is detected. Further, as the brake booster, a power piston slidably disposed in a shell, a constant-pressure chamber formed on the front side and a variable-pressure chamber formed on the rear side in the operation direction of the power piston, and a power piston shaft portion. A valve mechanism housed in the valve body, a pressure passage for supplying pressure fluid to the valve mechanism, and a flow path being switched by operating the valve mechanism to supply pressure fluid from the pressure passage to the variable pressure chamber for power supply. One having an input shaft for advancing a piston is already known. In this type of braking system, until the mechanical braking device operates, the regenerative braking force is increased or decreased according to an increase or decrease in the operation amount of the brake pedal, and the mechanical braking device starts braking and outputs the braking force. When you come to
The regenerative braking force is kept constant. [0003] However, in the above-mentioned conventional braking system, the regenerative braking force is increased according to an increase in the operation amount of the brake pedal only until the mechanical braking device starts braking. Since the regenerative braking force is increased, the regenerative braking force when the mechanical braking device starts braking cannot be increased, and the regenerative braking force of the regenerative braking device cannot be effectively used. That is, in order to increase the regenerative braking force when the mechanical braking device starts braking and to effectively utilize the regenerative braking force, it is necessary to set the mechanical braking device to start braking only by giving a large operation amount. For this purpose, the set load of the return spring of the master cylinder and the return spring of the hydraulic brake booster constituting the mechanical braking device may be increased. However, if such a setting is performed, in the unlikely event that the regenerative braking device does not operate, the braking force of the mechanical braking device will not be obtained until the brake pedal is largely operated, and the braking force will not be obtained. Feels ineffective. In view of such circumstances, the present invention makes it possible to increase the regenerative braking force when the mechanical braking device starts braking, thereby enabling its effective use, and at the same time, the regenerative braking device is activated. An object of the present invention is to provide a braking system for an electric vehicle in which a mechanical braking device can be operated with a small operation amount even when the braking operation is not performed. [0004] That is, the present invention relates to the above-described conventional electric vehicle braking system, wherein the pressure passage is provided in the pressure passage until a maximum regenerative braking force is obtained by the regenerative braking device. And a valve for opening the pressure passage when the maximum regenerative braking force is obtained. According to the above construction, when the brake pedal is depressed, the regenerative braking device immediately generates a regenerative braking force in accordance with an increase or decrease in the operation amount of the brake pedal. On the other hand, in a mechanical braking device, an on-off valve provided in a pressure passage of the brake booster closes the pressure passage until a maximum regenerative braking force is obtained by the regenerative braking device. Even if the valve mechanism is switched by depressing the valve to make the pressure passage communicate with the variable pressure chamber, the pressure fluid is not introduced into the variable pressure chamber, and therefore, the boosting operation by the brake booster is not performed. As a result, the braking force of the mechanical braking device is maintained at substantially zero, so that the braking operation of the regenerative braking device is effectively performed. When the regenerative braking force by the regenerative braking device becomes maximum, the on-off valve is opened, so that the pressure fluid in the pressure passage is introduced into the variable pressure chamber. As a result, a boosting action by the brake booster can be obtained, and thereafter, the braking force can be effectively increased by the mechanical brake.
Furthermore, in the unlikely event that the regenerative braking device does not operate, the above-mentioned on-off valve may be kept open, so that when the valve mechanism is switched by depressing the brake pedal, the boosting action by the brake booster is immediately performed. Is obtained, so that the braking operation with a sense of security can be performed while the depression force of the brake pedal is small. DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to an illustrated embodiment. Referring to FIG. 1, a braking system for an electric vehicle is configured to increase or decrease a mechanical braking force in accordance with an increase or decrease in a depression force of a brake pedal 1. 2 and a regenerative braking device 3 for increasing or decreasing a regenerative braking force in accordance with an increase or decrease in the stroke amount of the brake pedal 1. The mechanical braking device 2 includes a conventionally known negative pressure type brake booster 5 described in detail later. The brake booster 5 includes a negative pressure supply source such as a pump driven by a motor (not shown). Negative pressure is supplied from 6 through a negative pressure passage 7. The brake booster 5 is connected to the input shaft 8 of the brake booster 5 so as to be swingable about a pin 10.
, The stepping force applied to the input shaft 8 can be boosted and transmitted to a master cylinder (not shown). The brake fluid pressure generated in the master cylinder is supplied to a wheel cylinder (not shown) of the wheel to generate a mechanical braking force. On the other hand, the regenerative braking device 3 performs a regenerative braking operation at the time of braking by using a drive motor 11 that drives wheels of an electric vehicle, as is well known in the related art.
Is provided with a sensor 12 for detecting the stroke amount as the operation state of the brake pedal 1, and a control device 13 for inputting a signal from the sensor 12. The control device 13 increases the regenerative braking force up to the maximum regenerative braking force of the regenerative braking device 3 when the brake pedal 1 is depressed in accordance with the increase in the stroke amount of the brake pedal 1, and the regenerative braking control is performed. After the power reaches the maximum regenerative braking force, the maximum regenerative braking force is maintained even when the brake pedal 1 is depressed thereafter. It is well known that the maximum regenerative braking force obtained by the regenerative braking device is not always constant, but varies depending on the number of revolutions of the drive motor 11 and the like. Next, the brake booster 5 includes a substantially cylindrical valve body 16 slidably provided in a sealed shell 15, and a power piston 17 provided on an outer peripheral portion of the valve body 16 and a rear thereof. The pressure chamber 2 formed inside the shell 15 on the front side in the operation direction by the diaphragm 18 attached to the side.
0 and a transformation chamber 21 formed on the rear side. A negative pressure is supplied to the constant pressure chamber 20 from the negative pressure supply source 6 via the negative pressure passage 7. FIG.
As shown in the enlarged view, a conventionally known valve mechanism 25 including a vacuum valve 22 and an atmospheric valve 23 is provided in the valve body 16, and the valve mechanism 25 operates in conjunction with the input shaft 8. It is supposed to be. The valve mechanism 25 includes:
A valve plunger 26 slidably fitted to the valve body 16, a first valve seat 27 formed on the inner peripheral surface of the valve body 16 to constitute the vacuum valve 22, and a rear side of the valve plunger 26; A second valve seat 28 that constitutes the atmospheric valve 23 and a valve body 31 that is urged from the right by a spring 30 and seated on the first valve seat 27 or the second valve seat 28. . And the first valve seat 27
The outside of the seat portion of the valve body 31 is communicated with the constant pressure chamber 20 through a passage 32 formed in the valve body 16,
Further, the first valve seat 27 and the valve element 31 and the second valve seat 28
The intermediate portion of each seal between the valve body 31 and the valve body 31 is connected to the valve body 16.
The inside of the seat portion between the second valve seat 28 and the valve element 31 is connected to the atmosphere via a pressure passage 35 and an on-off valve 36 (FIG. 1) described later. Is communicated to. The distal end face of the valve plunger 26 constituting the valve mechanism 25 is a plate plunger 37.
1, the output shaft 38 is opposed to a reaction disk 39 housed in a recess formed in the base of the output shaft 38, and the output shaft 38 penetrates the seal member 40 and is outside the shell 15 as shown in FIG. At the same time as the piston of the master cylinder described above. FIG. 2 again
, The pressure passage 35 is connected to the valve body 16.
And a passage 46 provided in a cover 45 provided outside the input shaft 8 and communicating with the passage 44, and a flexibility connected to the passage 46. And a conduit 47 having the same. The cover 45 provided outside the input shaft 8 is attached to the valve body 16.
The cover 45 closes the opening of the passage 44 formed in the end cylindrical portion 16a, and the cover 45 loosely fits the front end into the end cylindrical portion 16a and connects the rear end to the input shaft. 8 and a cylindrical diaphragm 51 provided outside the sleeve 50. Then, the front end of the diaphragm 51 is turned radially outward and rearward so that the end cylindrical portion 1 is formed.
6a is fixed to the end cylindrical portion 16a by a step formed on the inner periphery on the rear side and a retainer 52. On the other hand, the rear end of the diaphragm 51 is fixed to the sleeve 50 and the fixing member 5a.
3 and fixed to the input shaft 8. The fixing member 53 is fixed to the input shaft 8 by a retainer 54, and a spring 58 is elastically mounted between the distal end of the sleeve 50 and the valve body 16. The above sleeve 5
Numeral 0 has a cylindrical connecting portion 50a extending radially outward from a central portion in the axial direction. The end of the conduit 47 is fitted into the connecting portion 50a and fixed by a clamp 56. As shown in FIG. 1, the above-described on-off valve 36 is provided in the conduit 47, and the on-off valve 36 is opened and closed by the control device 1.
3 can be controlled. Normally, that is, when the solenoid is not excited, the on-off valve 36 is connected to the conduit 47, that is, the pressure passage 3.
5 is opened so that the atmospheric pressure can be introduced into the valve mechanism 25. On the other hand, when the control device 13 detects the state in which the brake pedal 1 is not depressed by the sensor 12, the solenoid of the on-off valve 36 is deenergized to open the pressure passage 35, As soon as the sensor 12 detects that the brake pedal 1 is depressed from this state, the solenoid of the on-off valve 36 is excited to close the pressure passage 35, and the regenerative braking device 3 obtains the maximum regenerative braking force. When this is detected, the solenoid of the on-off valve 36 is deenergized again to open the pressure passage 35. In the above configuration, when the brake pedal 1 is not depressed, as described above, the control device 1
Numeral 3 deactivates the solenoid of the on-off valve 36 to open the pressure passage 35. When the brake pedal 1 is depressed from this state, the control device 13 that has detected the depression by the sensor 12 immediately causes the regenerative braking device 3 to perform the regenerative braking action. At this time, the control device 13 increases the regenerative braking force to the maximum regenerative braking force according to the increase in the stroke amount of the brake pedal 1. On the other hand, when the controller 12 detects that the brake pedal 1 is depressed by the sensor 12, the controller 13 immediately excites the solenoid of the on-off valve 36 to close the pressure passage 35. Therefore, in the mechanical braking device 2, the brake pedal 1
Is depressed, the vacuum valve 22 is closed and the atmosphere valve 23 is opened, whereby the pressure passage 35 is communicated with the variable pressure chamber 21. As described above, since the pressure passage 35 is closed by the on-off valve 36, Is not introduced into the transformation chamber 21, and therefore, the boosting action by the brake booster 5 is not performed. As a result, the braking force by the mechanical braking device 2 is kept to a minimum, so that the braking action by the regenerative braking device 3 can be effectively used.
When the control device 13 detects that the regenerative braking force by the regenerative braking device 3 has become the maximum regenerative braking force, the control device 13 opens the on-off valve 36 and the atmosphere is introduced into the variable pressure chamber 21. Will be allowed. As a result, a pressure difference is generated between the constant pressure chamber 20 and the variable pressure chamber 21, and the power piston 17 is advanced by the pressure difference, so that a boosting action by the brake booster 5 can be obtained. The braking force of the mechanical braking device 2 is increased according to the increase in the depression force of the brake pedal 1.
FIG. 3 shows another embodiment of the present invention. In the above embodiment, the connecting portion 50a is provided on the sleeve 50 and the connecting portion 5a is provided.
In contrast to the case where the conduit 47 is connected to the connection hole 50a, in the present embodiment, the connecting portion 50a is omitted and a communication hole 160 is formed in that portion, and the communication hole 160 of the sleeve 150 is connected to the conduit 147. Is covered with a cylindrical portion 147a. The conduit 147 is made of a flexible synthetic resin, and has a bellows-like bellows portion 147b and the tubular portion 147a integrally formed at the tip of the bellows portion 147b. On the other hand, the diaphragm 151 provided on the outer periphery of the sleeve 150 has an annular groove 151a formed on the outer peripheral surface thereof.
The right end of the cover member 153 is covered with the fixing member 153, and the inner peripheral surface thereof is brought into close contact with the outer peripheral surface of the input shaft 8, thereby sealing that portion. Then, the input shaft 8 is relatively moved to the cylindrical portion 14.
7a from the left side to the right side.
a, the inner surface of the right end portion is closely attached to the right end portion of the diaphragm 151 to seal the portion, and the cylindrical portion 147a
The inner peripheral edge of the left end of the annular groove 15 of the diaphragm 151
The cylindrical portion 147a is fixed to the diaphragm 151 while the portion is sealed by engaging with the diaphragm 1a. Other configurations are the same as those of the above embodiment except that the spring 58 mounted between the valve body 16 and the sleeve 150 is omitted, and the same members as those of the above embodiment are provided. The same numbers as those used are assigned. It is apparent that the present embodiment can provide the same operation and effect as the above-described embodiment. As described above, according to the present invention, the regenerative braking force when the mechanical braking device starts braking can be increased, so that the regenerative braking device can be effectively used. Even if the regenerative braking device does not operate, the mechanical braking device can be operated with a small brake pedal operation amount by opening the on-off valve, The effect is obtained that a braking action with a sense of security can be performed while the pedal effort is small.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram showing one embodiment of the present invention. FIG. 2 is an enlarged sectional view showing a main part of FIG. FIG. 3 is an enlarged sectional view of a main part showing another embodiment of the present invention. [Description of symbols] 1 ... Brake pedal 2 ... Mechanical braking device 3 ... Regenerative braking device 5 ... Brake booster 13 ... Control device 35 ... Pressure passage 36 ... Open / close valve 45 ... Cover

──────────────────────────────────────────────────の Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B60L 7/24 B60T 13/52

Claims (1)

(57) [Claim 1] A mechanical braking device provided with a brake booster for boosting the depression force of a brake pedal, a sensor for detecting an operation state of the brake pedal, and a sensor A regenerative braking device that increases or decreases a regenerative braking force in accordance with an increase or decrease in the detected operation amount of the brake pedal. The brake booster includes a power piston slidably disposed in a shell, and a power piston of the power piston. A constant pressure chamber formed on the front side in the operation direction and a variable pressure chamber formed on the rear side, a valve mechanism housed in a valve body of the power piston shaft, a pressure passage for supplying a pressure fluid to the valve mechanism, and the valve mechanism Actuating to switch the flow path, and an input shaft for supplying a pressure fluid from the pressure passage to the variable pressure chamber to advance the power piston, the braking system for an electric vehicle, The pressure passage is provided with an on-off valve that closes the pressure passage until the maximum regenerative braking force is obtained by the regenerative braking device and opens the pressure passage when the maximum regenerative braking force is obtained. Electric vehicle braking system.