JPS6141777B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a brake hydraulic pressure control device that can approximate the brake force distribution between front and rear wheels to an ideal brake force distribution curve.

Generally speaking, a brake fluid pressure control device directly introduces brake fluid pressure to the front and rear wheels when the braking force from the front and rear wheels is less than a predetermined value, and when the braking force exceeds a predetermined value, the brake fluid pressure is applied to the rear wheels. This system introduces reduced brake fluid pressure to achieve a braking force distribution that always locks the front and rear wheels simultaneously. Conventionally, as a type of brake fluid pressure control device, an inertia valve mechanism consisting of an inertia ball and a valve seat on which it is seated has been used to detect the control start point of the rear wheel brake fluid pressure. What was there is known.

However, conventional hydraulic control devices equipped with such an inertia valve mechanism usually operate the proportion valve by seating an inertia ball on the valve seat and blocking the flow path, so it is difficult to operate the proportion valve when the vehicle is empty or when the vehicle is loaded. At all times, it has been difficult to always achieve the ideal distribution of braking force. That is, as shown in Fig. 1, if the ideal brake fluid pressure distribution curve when the vehicle is empty is indicated by symbol a, and the ideal brake fluid pressure distribution curve when the vehicle is loaded is indicated by symbol b, then the brake fluid pressure distribution by the brake fluid pressure control device is It is preferable to set the curve to curve A consisting of straight line c and straight line d when the vehicle is empty, and to curve B consisting of straight line c and straight line e when loaded, but in a brake hydraulic pressure control device using the above mechanism. To obtain the above curve A when the vehicle is empty, for example, if the inertia ball is set to sit on the valve seat at point A on the straight line c where the deceleration of the vehicle is 0.2g, then when the vehicle is loaded, the weight will be reduced by 0.2g due to the increase in vehicle weight. Even though a higher hydraulic pressure than the hydraulic pressure at point A above is required to obtain speed, the deceleration of the vehicle at point B, which is slightly higher than point A, is 0.2g, and as a result, The braking force distribution curve when loaded is a curve consisting of straight line c and straight line f, resulting in insufficient braking force.

Furthermore, in the conventional brake hydraulic pressure control device using such an inertial valve mechanism, it is difficult to always obtain good braking force and directional stability of the vehicle, especially when braking when the vehicle is empty or in a near-empty state. It was hot. That is, when the empty vehicle characteristic curve A is very low, the inertial ball must be seated on the valve seat at a low vehicle deceleration; If this setting is made, the inertia ball may not sit on the valve seat at the proper time due to external factors such as vehicle vibration or when the vehicle is going downhill, and the braking force on the rear wheel side becomes too large, causing a skid. On the other hand, it also had the disadvantage that the braking force on the rear wheels was too small, resulting in insufficient braking force.

SUMMARY OF THE INVENTION In view of these drawbacks, the present invention provides a brake hydraulic pressure control device that can always perform good braking force distribution under all loading conditions.

The present invention will be described below based on the illustrated embodiment. In FIG. 2, 1 is the main body of the brake fluid pressure control device, 2 and 3 are input holes and output holes respectively formed in this main body, and the input hole 2 is a conduit. 4 to one system of the master cylinder 5, and the output hole 3 to the rear wheel cylinder 7 through a conduit 6, and as described in detail later, the input hole 2 and the output hole 3 are connected to each other. The brake fluid pressure generated in the master cylinder 5 can be supplied to the rear wheel cylinder 7. Furthermore, the other system of the master cylinder 5 communicates directly with the front wheel cylinder 9 via a conduit 8.

A plunger 12 provided with a seal member 11 is slidably fitted into a hole 10 bored in the main body 1, and a medium diameter portion 12a and a small diameter portion 12b formed at the distal end of the plunger 12 are inserted into the main body. A rod 12 is provided at the tip of the plunger 12, and a rod 12 is provided at the tip of the plunger 12.
c is formed protrudingly. The hole 15 is provided in the shaft portion of a sleeve 18 inserted into a hole 17 in a body 16 constituting the main body 1 via a sealing member.

Therefore, the retainer 20 is brought into contact with the stepped portion 19 between the medium diameter portion 12a and the small diameter portion 12b of the plunger 12, and a spring 21 is elastically loaded between the retainer 20 and the end wall of the sleeve 18. ,
Due to the elastic force of this spring 21, the plunger 12
is biased toward the left in FIG. 2, and the rod 12c at the other end of the plunger 12 is loosely fitted through the through hole 22 and projected. On the other hand, a valve body 23 that is pushed up by the rod 12c is disposed at the tip of the rod 12c, and this valve body 23 is seated by a spring 24 on a valve seat 25 formed around the through hole 22. I am encouraging them to do so. At this time, since the elastic force of the spring 21 is set larger than the elastic force of the spring 24, under normal conditions, the plunger 12
is held in the non-operating position shown, and the valve body 23 is held away from the valve seat 25 by the rod 12c. These plunger 12, spring 21, valve body 23, etc. constitute a proportion valve that reduces the braking fluid pressure from the master cylinder at a predetermined rate and supplies it to the rear wheel cylinder. In this state, the input hole 2 and the output hole 3 are connected to the seal member 11 provided on the plunger 12 and the seal member 1 provided on the main body 1.
3, a passage 27 communicating with this passage 26, a chamber 28, a passage 29, a gap between the valve body 23 and the valve seat 25, and a through hole 22, which communicate with each other, and Braking fluid pressure in the cylinder 5 can be supplied to the rear wheel cylinder 7.

Next, in a small diameter hole 30 connected to the hole 17 of the body 16, an annular support member 32 is fitted while maintaining liquid tightness with a seal member 31, and a poppet type pressure transmission member 33 is housed. There is. This transmission member 33 is supported by a substantially annular elastic body 34 baked between its head 33a and the support member 32, and in its non-operating state, the transmission member 33 passes through the opening of the support member 32. A required gap S is formed between the end surface of the shaft portion 33b and the opposing end surface of the small diameter portion 12b of the plunger 12. The chamber 35 on the transmission member head 33a side is kept liquid-tight by the seal member 31 and the elastic body 34.
It is communicated with the master cylinder 5 through the passage 36 and the chamber 28, etc., so that the brake fluid pressure from the master cylinder 5 can be introduced into the chamber 35. Therefore, when the brake fluid pressure is introduced into the chamber 35, the transmission member 33 is pressed and moved to the left while compressing and deforming the elastic body 34, and when the pressure inside the chamber 35 exceeds a specified value, In this case, the gap S is closed and the spring 21 comes into contact with the plunger 12, thereby increasing the biasing force of the spring 21 acting on the plunger 12.

Further, an inertia ball 37 for controlling the brake fluid pressure introduced into the chamber 35 is housed in the chamber 28 that communicates the master cylinder 5 with the chamber 35 .
This inertia ball 37 is housed in the chamber 28 so as to be movable back and forth in the direction of travel of the vehicle, and a valve seat 38 is provided at a position close to this inertia ball 37. Note that A ₁ is the cross-sectional area of the main body portion of the plunger 12, A ₂ is the cross-sectional area of the medium diameter portion 12a, A 3 is the effective pressure receiving area when the valve body 23 is seated on the valve seat 25, and A ₃ is the cross-sectional area of the main body portion of the plunger 12. The effective pressure receiving area is _A4 .

Next, the operation of the brake hydraulic pressure control device of the above embodiment will be explained.

(1) Operation when the inertia ball 37 is seated on the valve seat 38 before the transmission member 33 transmits pressure to the plunger 12 by the pressure in the chamber 35, such as when the vehicle is empty.

The brake fluid pressure generated within the master cylinder 5 is
Front wheel cylinder 9 directly via conduit 8
and the conduit 4, the input hole 2 of the brake fluid pressure control device main body 1, the passages 26, 27, the chamber 28,
Passage 29, gap between valve body 23 and valve seat 25, through hole 2
2. A chamber 35 on the rear side of the pressure transmitting member 33 is introduced into the rear wheel cylinder 7 via the output hole 3 and the conduit 6, and is introduced from the input hole 2 through the passages 26, 27, the chamber 28, and the passage 36. will be introduced in In the initial stage of braking, the input hole 2 and the output hole 3 are in communication with each other through a simple passage, and the brake fluid pressure in the master cylinder 5 is directly supplied to the rear wheel cylinder 7, while the front Since the brake fluid pressure in the master cylinder 5 is also directly supplied to the wheel cylinder 9, the straight line in Fig. 3
As shown by C', the front and rear wheel cylinders 7,
9, the same braking fluid pressure is introduced. When the brake fluid pressure supplied to the rear wheel cylinder 7 increases, the brake fluid pressure flowing through the passage 26 acts on the step between the main body of the plunger 12 and the middle diameter portion 12a, while Since the same circulating brake fluid pressure is acting on the left end of the plunger 12, the plunger 12 is moved to the right against the elastic force of the spring 21 due to the difference in the receiving area of the brake fluid pressure.
At point A' in FIG. 3, the valve body 23 is seated on the valve seat 25, and the brake fluid pressure supplied to the rear wheel cylinder 7 stops increasing. When the brake fluid pressure further increases, the force acting to move the plunger 12 to the right does not increase because the valve body 23 is seated, but it acts on the stepped portion of the plunger 12 to Since the acting force that causes the brake to move to the left increases as the hydraulic pressure increases, the plunger 12 moves to the left again, disengaging the valve body 23, and increasing the braking hydraulic pressure in the rear brake cylinder 7. As a result, the brake fluid pressure acting on the rear wheel cylinder 7, that is, the left end of the plunger 12 increases, and the plunger 12 is moved to the right again by that fluid pressure to seat the valve body 23, and therefore the brake is applied. The increase in hydraulic pressure causes the plunger 12 to move left and right, thereby increasing the braking hydraulic pressure in the rear wheel cylinder 7 at a lower rate of increase than the increase in hydraulic pressure in the master cylinder 5 side.

Here, the relational expression of the force acting on the plunger 12 is P _r (A ₁ - A ₃ ) + P _n A ₃ = P _n (A ₁ - A ₂ ) + F _s ...
... is shown by (1). However, P _n is the pressure on the input hole 2 side,
P _r is the pressure on the output hole 3 side, and F _s is the set load of the spring 21.

Rewriting this equation (1), P _r =A ₁ -A ₂ -A ₃ /A ₁ -A ₃ P _n +F _s /A ₁
-A ₃ ...(2) Therefore, as is clear from this equation, the pressure P _r at the output hole 3, that is, the rear wheel cylinder 7 side, is a linear function of the pressure at the input port 2 side, and the third
As shown by straight line d' in the figure, it will rise at a constant rate.

In this way, the front wheel cylinder 9
When the brake fluid pressure supplied to the rear wheel cylinder 7 increases, the pressure is transmitted by the brake fluid pressure introduced into the chamber 35 on the rear side of the pressure transmitting member 33 when the vehicle is empty as described above. Member 33
moves and transmits its hydraulic pressure to the plunger 12, the deceleration of the vehicle reaches a predetermined value, for example,
At two points in FIG. 3, the inertia ball 37
8, the increase in brake fluid pressure introduced into the chamber 35 is regulated. Therefore, in this case, the force that biases the plunger 12 to the left is only the elastic force of the spring 21, and the brake fluid pressure distribution curve for the front and rear wheels is a curve A' corresponding to the curve A in FIG. becomes.

(2) When the predetermined deceleration cannot be obtained even if the braking fluid pressure increases, such as when overloading, the pressure transmitting member 33 moves and transmits force to the plunger 12,
Moreover, this operation occurs when the inertial ball 37 is not seated on the valve seat 38.

In this case, at the initial stage of braking, the same operation as described above is carried out, and the brake fluid pressure distribution between the front and rear wheels is carried out along straight lines c' and d' in Fig. 3, but at point 2 in Fig. 3, However, since the specified deceleration cannot be obtained,
The inertia ball 37 does not sit on the valve seat 38, and therefore, as the brake fluid pressure increases, the chamber 3
The hydraulic pressure in the chamber 35 also rises, and finally the pressure transmitting member 33 moves enough to close the gap S, and at point H in FIG. It will be transmitted to

At this time, the force F acting on the pressure transmission member 33
is expressed as F= _A4・_Ps −n (3). Here, P _s is the pressure inside the chamber 35, n
is a constant representing the acting force of the elastic body 34 that supports the transmission member 33. Therefore, the relational expression of the force acting on the plunger 12 can be obtained by adding F in equation (3) to the right side of equation (1) and rearranging as P _s =P _n .

P _r =A ₁ -A ₂ -A ₃ +A ₄ /A ₁ -A ₃・P _n -n
-F _s /A ₁ -A ₃ ...(4) This equation (4) is shown as the straight line g in FIG.

In this way, the pressure in the chamber 35 is transmitted to the plunger 12 via the pressure transmitting member 33, and the hydraulic pressure _Ps , that is, _Pn , introduced into the chamber 35 by pushing the plunger 12 to the left, is increased as shown in FIG. When the temperature exceeds the point F, the plunger 12 receives the force from the pressure transmitting member 33 and is pressed and held in the non-operating position shown in the figure, so that the valve body 23 is held in the open state.
The hydraulic pressures supplied to the wheel cylinders 7 and 9 of the front and rear wheels are substantially the same pressure (see straight line c'' in Figure 3),
Powerful braking is performed by the front and rear wheels.

(3) Operation when the inertia ball 37 is seated on the valve seat 38 while the pressure transmission member 33 is transmitting force to the plunger 12, such as during light load or constant volume.

In braking at a light load, for example, a predetermined deceleration can be obtained at point T on straight line g in FIG.
An inertia ball 37 is seated on the valve seat 38. Then,
Communication between the master cylinder 5 and the chamber 35 is cut off,
The chamber 35 is filled with the hydraulic pressure when the inertia ball 37 is seated on the valve seat 38. If the pressure sealed in the chamber 35 at this time is _Ps1 , then the relational expression of the force acting on the plunger 12 is P _r = A ₁ - _{A 2} - A ₃ / from equations (2) and (3). A ₁ −A ₃ P _n +F _s +A ₄
P _s1 −n/A ₁ −A ₃ (5), which is expressed as a straight line h parallel to the straight line d'.

On the other hand, in braking at constant volume, a predetermined deceleration is obtained, for example, at a point on the straight line c'' in _FIG . ), the following equation is obtained.

P _r =A ₁ -A ₂ -A ₃ /A ₁ -A ₃ P _n +F _s +A ₄
P _s2 −n+f/A ₁ −A ₃ ...(6) In this case, the pressure P _s2 at which the inertia ball 37 closes is obtained at the point C above, but the characteristic of equation (6) is obtained at the point C' in Figure 3. It is indicated by the broken straight line e′. As is clear from the comparison of equations (5) and (6) above, the delay in the break point from point H to point C' is due to the force f that tries to prevent the plunger 12 from moving to the right in equation (6). This is because it is added. The generation of this force f, in other words, the delay from point I to point C' occurs mainly for the following reasons. That is, the above-mentioned straight line e' is obtained by the operation of the proportion valve, that is, by the left and right displacement of the plunger 12, but in order for the plunger 12 to move to the right, the pressure transmitting member 3 that is in contact with the plunger 12 simultaneously moves to the right.
3 also needs to move to the right. However, room 35
Since the pressure oil inside is sealed by the seating of the inertia ball 37 on the valve seat 38, the pressure transmitting member 38 is in an oil-locked state, so that the inertia ball 37 is seated on the valve seat 38 at the point After that, until the pressure reaches point C, the pressure transmitting member 33
cannot move to the right. Then, when the pressure rises to point C' and the force that moves the plunger 12 and the pressure transmitting member 33 to the right increases, and the pressure inside the chamber 35 increases accordingly, the elastic body 34
deforms while keeping the volume inside the chamber 35 the same, allowing the pressure transmitting member 33 to move to the right. In other words, elastic body 3
4 deforms as the pressure transmitting member 33 moves to the right, and at the same time bulges outward by the volume reduction in the chamber 35 due to the rightward movement of the pressure transmitting member 33, thereby reducing the volume in the chamber 35. The pressure transmitting member 33 is allowed to move to the right without changing. The above f indicates the value of the force when the proportion valve restores its function, and since the value is substantially the same thereafter, the above straight line e' is obtained.

However, in the present invention, the elastic body 34 is disposed between the head 33a of the pressure transmitting member 33 and the end surface of the support member 32, and when the pressure transmitting member 33 is displaced to the left, the elastic body 34 is Since it is configured so that almost only compressive force is applied, the durability can be significantly improved compared to when the elastic body is subjected to shear force, and the reliability of the brake hydraulic pressure control device is improved. can be done. Furthermore, by changing the cross-sectional shape of the elastic body 34 in various ways as shown in FIGS. 4 to 6, the delay from point I to point C' can be appropriately set.

As described above, according to the present invention, it is possible to always obtain the optimum braking force depending on the loading condition, and moreover, the elastic body that holds the pressure transmitting member in the non-operating position can be moved when the pressure transmitting member is displaced. Since the elastic body is arranged so that almost only compressive force acts on it, it is possible to improve the durability of the elastic body, thereby improving the reliability of the brake hydraulic pressure control device. Effects can be obtained.

In particular, in the present invention, the pressure transmission member is loosely inserted into the opening of the support member defining the proportion valve side of the chamber, surrounds the pressure transmission member, and is located between the enlarged diameter head portion of the pressure transmission member and the support member. Since it is sealed and held by the annular elastic body which is clamped and fixed to Even if the stroke range of the pressure transmitting member is small, it can still support a large pressure, and the volume of the chamber that holds the pressure transmitting member can be reduced to help miniaturize the mechanism. Even if an oil lock state occurs due to the seating of the inertia ball, the deformation of the elastic body allows the pressure transmitting member to be displaced in cooperation with the proportion valve, which has the effect of expanding the hydraulic control range.

[Brief explanation of the drawing]

FIG. 1 is a brake fluid pressure distribution curve diagram, FIG. 2 is a vertical sectional view showing an embodiment of the present invention, FIG. 3 is a brake fluid pressure distribution curve diagram of the device of the present invention, and FIGS. 4 to 6 are FIG. 7 is an enlarged cross-sectional view of main parts showing other embodiments of the present invention. 5... Master cylinder, 7... Rear wheel cylinder, 12... Plunger, 33... Pressure transmission member, 34... Elastic body, 35... Chamber, 37...
Inertial ball, S... gap.

Claims (1)

[Claims] 1 A proportion valve that reduces the braking fluid pressure from the master cylinder at a predetermined rate and supplies it to the rear wheel cylinder, and is pressed and displaced by the fluid pressure in the chamber that communicates with the master cylinder, and applies that fluid pressure to the rear wheel cylinder. a pressure transmitting member that transmits to the proportion valve to open the proportion valve; an elastic body that normally holds the pressure transmitter in an inoperative position with a predetermined gap between the proportion valve; The pressure transmitting member is provided with an inertia ball disposed in the middle of a communication path that communicates the master cylinder and the chamber, and blocks the communication path when the deceleration of the vehicle exceeds a predetermined value, and the pressure transmission member is connected to the chamber. The annular elastic body is loosely inserted into the opening of the support member that defines the proportion valve side of the pressure transmission member, and is clamped and fixed between the enlarged diameter head of the pressure transmission member and the support member. 1. A brake hydraulic pressure control device which is kept cold and is arranged so that substantially only compressive force acts on the elastic body when the pressure transmission member is displaced.